Journal articles: 'Amino acids – Analysis'

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Park, Kwang Sook, Sung-Youl Hong, Hyang Woo Lee, Sangduk Kim, and Woon Ki Paik. "HPLC analysis of methylated amino acids: Methylated amino acids on HPLC." Archives of Pharmacal Research 9, no. 1 (March 1986): 15–18. http://dx.doi.org/10.1007/bf02857700.

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Athmani, Hamza, and Nourreedine Benali-Cherif. "Structure and thermal analysis of amino acids." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C989. http://dx.doi.org/10.1107/s205327331409010x.

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The twenty amino acids are chemical compounds having two functional groups (carboxyl:-COOH, amine:-NH2) and an asymmetric carbon (except glycine). They are amphoteric and can exist as zwitterion. Because of the reactivity of amino acids (esterification, amidation, N-alkylisation, N-arylation, protonation), and their conformation (aliphatic, aromatic) chemical, properties (acid, base, and / or hydroxylated, solubility), and physical properties (absorbance, NLO), our laboratory contribute to the study (synthesis and X ray single crystal structures) of new organic-inorganic hybrid compounds which allows to the development of materials with novel properties [1-3]. Our work is also based on the relationship between the thermal decomposition of amino acids and their chemical structures, dozens compounds were selected and the results of the DTA, TG and DTG thermal decomposition was performed by several methods. Diffraction results are used for the identification of degradation mechanisms of the chemical structure, the stability of the compound studied and the anticipation of possible syntheses of hybrid compounds.

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Akhtar, Adil, and Tazid Ali. "Analysis of Unweighted Amino Acids Network." International Scholarly Research Notices 2014 (December 16, 2014): 1–6. http://dx.doi.org/10.1155/2014/350276.

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The analysis of amino acids network is very important to studying the various physicochemical properties of amino acids. In this paper we consider the amino acid network based on mutation of the codons. To analyze the relative importance of the amino acids we have discussed different measures of centrality. The measure of centrality is a powerful tool of graph theory for ranking the vertices and analysis of biological network. We have also investigated the correlation coefficients between various measures of centrality. Also we have discussed clustering coefficient as well as average clustering coefficient of the network. Finally we have discussed the degree of distribution as well as skewness.

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Campo, Vanessa L., Áurea D. L. Borges, and Ivone Carvalho. "HPLC analysis of glycosylated amino acids." Journal of the Brazilian Chemical Society 17, no. 4 (August 2006): 648–54. http://dx.doi.org/10.1590/s0103-50532006000400004.

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Sandberg, M., H. Hagberg, I. Jacobson, B. Karlsson, A. Lehmann, and A. Hamberger. "Analysis of amino acids: Neurochemical application." Life Sciences 41, no. 7 (August 1987): 829–32. http://dx.doi.org/10.1016/0024-3205(87)90173-1.

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Papadoyannis, Ioannis N., and Georgios A. Theodoridis. "ChemInform Abstract: Amino Acids: HPLC Analysis." ChemInform 41, no. 28 (June 17, 2010): no. http://dx.doi.org/10.1002/chin.201028272.

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Bora, Pranjal Kumar, Pankaj Hazarika, and Arun Kumar Baruah. "Distance based amino acids network analysis." Gene Reports 21 (December 2020): 100933. http://dx.doi.org/10.1016/j.genrep.2020.100933.

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Tsikas, Dimitrios, and Alexander A. Zoerner. "Analysis of eicosanoids, amino acids, organic acids, and microRNAs." Journal of Chromatography B 964 (August 2014): vii—viii. http://dx.doi.org/10.1016/j.jchromb.2014.06.001.

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Jacoby, George A., Marian A. Corcoran, Debra M. Mills, Caitlin M. Griffin, and David C. Hooper. "Mutational Analysis of Quinolone Resistance Protein QnrB1." Antimicrobial Agents and Chemotherapy 57, no. 11 (August 26, 2013): 5733–36. http://dx.doi.org/10.1128/aac.01533-13.

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ABSTRACTAlanine substitutions and selected deletions have been used to localize amino acids in QnrB essential for its protective activity. Essential amino acids are found at positions i and i−2in the pentapeptide repeat module and in the larger of two loops, where deletion of only a single amino acid compromises activity. Deletion of 10 amino acids at the N terminus is tolerated, but removal of 3 amino acids in the C-terminal dimerization unit destroys activity.

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Gu, Shuang-Xi, Hai-Feng Wang, Yuan-Yuan Zhu, and Fen-Er Chen. "Natural Occurrence, Biological Functions, and Analysis of D-Amino Acids." Pharmaceutical Fronts 02, no. 02 (June 2020): e79-e87. http://dx.doi.org/10.1055/s-0040-1713820.

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AbstractThis review covers the recent development on the natural occurrence, functional elucidations, and analysis of amino acids of the D (dextro) configuration. In the pharmaceutical field, amino acids are not only used directly as clinical drugs and nutriments, but also widely applied as starting materials, catalysts, or chiral ligands for the synthesis of active pharmaceutical ingredients. Earler belief hold that only L-amino acids exist in nature and D-amino acids were artificial products. However, increasing evidence indicates that D-amino acids are naturally occurring in living organisms including human beings, plants, and microorganisms, playing important roles in biological processes. While D-amino acids have similar physical and chemical characteristics with their respective L-enantiomers in an achiral measurement, the biological functions of D-amino acids are remarkably different from those of L-ones. With the rapid development of chiral analytical techniques for D-amino acids, studies on the existence, formation mechanisms, biological functions as well as relevant physiology and pathology of D-amino acids have achieved great progress; however, they are far from being sufficiently explored.

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Chi, Chang Feng, Jian She Zhang, Chang Wen Wu, Mei Ying Xu, and Bin Wang. "Analysis and Evaluation of Nutrition Composition of Mussel." Advanced Materials Research 554-556 (July 2012): 1455–58. http://dx.doi.org/10.4028/www.scientific.net/amr.554-556.1455.

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The nutrient components of mussel, including crude protein, crude fat, crude ash, vitamins and composition of amino acids, were analyzed in this study. The crude protein content ranged from 42.23% in S8 to 45.62% in S2. The crude fat content was generally ranging from 2.33% to 2.68%. The crude ash ranged from 1.08% to 1.67%. The total sugar content ranged from 1.23% to 1.31%. VA showed the highest contents and the content ranged from 202.32±0.30 mg/100g in S7 to 212.23±1.37 mg/100g in S5 among all the vitamins. The content of cholesterol ranged from 421.32±3.17 mg/100g in S7 to 445.12±2.43 in S1. The content of riboflavin ranged from 0.54±0.03 mg/100g in S7 to 0.63±0.05 in S3. The content of lecithin ranged from 1.20±0.07 mg/100g in S8 to 1.41±0.09 in S1. The content of unsaturated fatty acids ranged from 18.2±1.31 mg/100g in S8 to 22.9±1.49 in S5. The content of EAA was in the order of Leu > Lys > Thr > Phe >Ile > Val > Met .The ratio between essential amino acids and total amino acids was 39.18 %. The ratio between essential amino acids and total amino acids as well as the ratio between essential amino acids and nonessential amino acids in the amino acid composition of good quality proteins were about 86%, respectively proposed by FAO/WHO. The content of delicious amino acids in mussel was 15.53%, accounting for 36.72 % of total amino acids, which is an important reason for the particularly delicious of mussel.

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Cui, Lili, Guoquan Feng, Jie Lu, and Changqin Li. "The Content Analysis of Amino Acids in Auricularia auricula from Heilongjiang and Jilin." Journal of Food Quality 2021 (November 27, 2021): 1–5. http://dx.doi.org/10.1155/2021/8886519.

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The content of amino acids in Auricularia auricula was analyzed by the method of acid hydrolysis and automatic online analysis. The content of total amino acids in A. auricula produced in Heilongjiang was between 68.287 and 110.949 mg/g, and the average was 90.848 mg/g. The content of essential amino acids in A. auricula from Heilongjiang was between 28.847 and 45.757 mg/g, and the average was 37.987 mg/g. The proportion of essential amino acids (EAA) to total amino acids (TAA) in A. auricula from Heilongjiang was between 41.24% and 42.26%. However, the content of total amino acids in A. auricula from Jilin was between 71.716 and 124.143 mg/g, and the average was 94.318 mg/g. The content of essential amino acids in A. auricula from Jilin was between 29.775 and 52.063 mg/g, and the average was 38.498 mg/g. The ratio of essential amino acids (EAA) to total amino acids (TAA) in A. auricula from Jilin was between 39.75% and 41.94%. The content of total amino acids and essential amino acids in A. auricula from Jilin was higher than that from Heilongjiang. However, EAA/TAA in A. auricula from Heilongjiang was higher than that of Jilin. The content of total amino acids in different batches of A. auricula in the same production area was quite different, but the ratio of essential amino acids content to total amino acids content was basically the same.

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Peng, Lian-Xin, Liang Zou, Mao-Ling Tan, Yuan-Yuan Deng, Juan Yan, Zhu-Yun Yan, and Gang Zhao. "Free amino acids, fatty acids and phenolic compounds in Tartary buckwheat of different hull colour." Czech Journal of Food Sciences 35, No. 3 (June 28, 2017): 214–22. http://dx.doi.org/10.17221/185/2016-cjfs.

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In this paper, free amino acids, fatty acids, and phenolic compounds in buckwheat of different hull colour were quantified by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), gas chromatography-mass spectrometry (GC-MS), and high performance liquid chromatography-ultraviolet detector (HPLC-UV), respectively. A total of 20 free amino acids, 8 fatty acids, and 6 phenolic compounds were detected in Tartary buckwheat flour and bran. The data on concentrations were subjected to common chemometric analyses, including principal component analysis (PCA) and hierarchical cluster analysis (HCA), to gain better understanding of the differences between the tested samples. Results indicated that most of the free amino acids, fatty acids, and phenolic compounds were higher in bran than in flour, and there is no significant difference in respect to the hull colour. Our results may be helpful for quality control in Tartary buckwheat and its products in the future.

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Li, Wan Jun, Shun Sheng Chen, and Wei Qiang Qiu. "Comparative Analysis of Amino Acid Composition in Antarctic Krill and White Shrimp." Advanced Materials Research 941-944 (June 2014): 1114–19. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.1114.

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The purpose of this experiment is to evaluate the nutritional value of amino acids and its commercial value in the fish processing sector in Antarctic krill with cross-referenced in the white shrimp. For determination of the composition of 17 amino acids in the two shrimp muscle, free amino acids were measured using sulfosalicylic acid method, hydrolysed amino acid using hydrochloric acid hydrolysis.17 kinds of hydrolysed amino acids are measured in the muscle of Antarctic krill and White shrimp, which total content is 513.59±18.56mg/g and 537.61±16.8mg/g respectively.16 kinds of free amino acids are measured, which total content is 616.88±44.61mg/100g and 1276±75.67mg/100g respectively, while cysteine is not found. According to amino acid score (AAS), chemical score (CS), the limiting amino acid of Antarctic krill and White shrimp is valine and methionine + cysteine. The umani amino acids accounted for 27.76% of free amino acids and 35.69% of hydrolysed amino acids in Antarctic krill, while White shrimp is 41.08% and 31.52% respectively. The amino acids in Antarctic krill, TAV of which is greater than 1, include glutamic acid, alanine, lysine and arginine.

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Moughan, Paul J. "Amino acid availability: aspects of chemical analysis and bioassay methodology." Nutrition Research Reviews 16, no. 2 (December 2003): 127–41. http://dx.doi.org/10.1079/nrr200365.

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AbstractIt is important to be able to characterise foods and feedstuffs according to their available amino acid contents. This involves being able to determine amino acids chemically and the conduct of bioassays to determine amino acid digestibility and availability. The chemical analysis of amino acids is not straightforward and meticulousness is required to achieve consistent results. In particular and for accuracy, the effect of hydrolysis time needs to be accounted for. Some amino acids (for example, lysine) can undergo chemical modification during the processing and storage of foods, which interferes with amino acid analysis. Furthermore, the modified amino acids may also interfere with the determination of digestibility. A new approach to the determination of available lysine using a modifiedin vivodigestibility assay is discussed. Research is required into other amino acids susceptible to structural damage. There is recent compelling scientific evidence that bacterial activity in the small intestine of animals and man leads to the synthesis and uptake of dietary essential amino acids. This has implications for the accuracy of the ileal-based amino acid digestibility assay and further research is required to determine the extent of this synthesis, the source of nitrogenous material used for the synthesis and the degree of synthesis net of amino acid catabolism. Although there may be potential shortcomings in digestibility assays based on the determination of amino acids remaining undigested at the terminal ileum, there is abundant evidence in simple-stomached animals and growing evidence in human subjects that faecal-based amino acid digestibility coefficients are misleading. Hindgut microbial metabolism significantly alters the undigested dietary amino acid profile. The ileal amino acid digestibility bioassay is expected to be more accurate than its faecal-based counterpart, but correction of the ileal amino acid flow for amino acids of endogenous origin is necessary. Approaches to correcting for the endogenous component are discussed.

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Moldoveanu, SC. "Analysis of Protein Amino Acids in Tobacco Using Microwave Digestion of Plant Material." Beiträge zur Tabakforschung International/Contributions to Tobacco Research 21, no. 8 (December 1, 2005): 451–65. http://dx.doi.org/10.2478/cttr-2013-0813.

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AbstractThis paper describes a technique using microwave digestion and gas chromatography-mass spectrometry (GC-MS), which makes possible the analysis of protein amino acids in tobacco. The technique involves first the measurement of free amino acids, a hydrolysis using microwave digestion, and a measurement of total resulting amino acids. The content of protein amino acids is determined from the difference of total and free amino acids. The digestion is performed with aqueous 6 N HCl (with 1% phenol) for two hours in a microwave at 120°C in sealed vials. The GC-MS analysis is performed after the amino acids are derivatized with N-methyl-N-(t-butyldimethylsilyl)trifluoroacetamide (MTBSTFA). The technique provides reliable results with less than 10% relative standard deviation (RSD) for most amino acids. Only the determination of very low level amino acids is affected by larger errors. The method provides results for free amino acids that are in very good agreement with those obtained by high performance liquid chromatography (HPLC), and also results for protein levels in tobacco in agreement with data previously reported in the literature. Results are given for several single grade tobaccos and for tobacco blends from four Kentucky reference cigarettes.

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Choi, Kwang-Eun, Eunkyoung Chae, Anand Balupuri, Hye Ree Yoon, and Nam Sook Kang. "Topological Water Network Analysis Around Amino Acids." Molecules 24, no. 14 (July 22, 2019): 2653. http://dx.doi.org/10.3390/molecules24142653.

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Water molecules play a key role in protein stability, folding, function and ligand binding. Protein hydration has been studied using free energy perturbation algorithms. However, the study of protein hydration without free energy calculation is also an active field of research. Accordingly, topological water network (TWN) analysis has been carried out instead of free energy calculation in the present work to investigate hydration of proteins. Water networks around 20 amino acids in the aqueous solution were explored through molecular dynamics (MD) simulations. These simulation results were compared with experimental observations. Water molecules from the protein data bank structures showed TWN patterns similar to MD simulations. This work revealed that TWNs are effected by the surrounding environment. TWNs could provide valuable clues about the environment around amino acid residues in the proteins. The findings from this study could be exploited for TWN-based drug discovery and development.

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Prest, Jeff E., Sara J. Baldock, Peter R. Fielden, Nicholas J. Goddard, and Bernard J. Treves Brown. "Analysis of amino acids by miniaturised isotachophoresis." Journal of Chromatography A 1051, no. 1-2 (October 2004): 221–26. http://dx.doi.org/10.1016/j.chroma.2004.05.026.

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Savych, Alona, Olha Polonets, Liubov Morozova, Kateryna Syrovatko, and Tetiana Recun. "HPLC-FLD analysis of amino acids content in Chrysanthemum morifolium." Pharmacia 69, no. 2 (April 12, 2022): 337–43. http://dx.doi.org/10.3897/pharmacia.69.e82097.

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Chrysanthemum morifolium (Asteraceae family) have long been used as a tonic, antioxidant, antipyretic, analgesic, sedative, antitumor, neuroprotector, hepatoprotector and cardioprotector agent. This species should be reconsidered as possible sources of many biocompounds, especially amino acids. Thus, the aim of this study was to validate the chromatographic method for detection of amino acids and their identification in flowers and leaves of Ch. morifolium of variant Pectoral. HPLC-FLD method was evaluated in terms of linearity, precision, repeatability, accuracy, LOD and LOQ. The calibration curves of all analytical standards of amino acids were linear (R2 > 0.99) over the range of 0.015–0.625 μmol/mL, the LODs and the LOQs were in the range of 0.001–0.096 µg/mL and 0.004–0.321 µg/mL, respectively. During the HPLC-FLD assay ten amino acids in free form and fifteen amino acids after hydrolysis in Ch. morifolium flowers were identified. Besides, twelve amino acids were detected in free form and fourteen amino acids after hydrolysis in Ch. morifolium leaves. The results of HPLC-FLD analysis showed that the predominant amino acid was L-proline in both types of herbal raw materials. Its total content was 31.67±0.02 μg/mg in Ch. morifolium flowers and 18.56±0.02 μg/mg in Ch. morifolium leaves. This phytochemical study confirms that flowers and leaves of Ch. morifolium (Pectoral) are rich sources of amino acids and can exhibit a wide range of pharmacological activities.

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Shikata, Nahoko, Yukihiro Maki, Masahiko Nakatsui, Masato Mori, Yasushi Noguchi, Shintaro Yoshida, Michio Takahashi, Nobuo Kondo, and Masahiro Okamoto. "Determining important regulatory relations of amino acids from dynamic network analysis of plasma amino acids." Amino Acids 38, no. 1 (January 3, 2009): 179–87. http://dx.doi.org/10.1007/s00726-008-0226-3.

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Yu, Yi-Ping, and Shih-Hsiung Wu. "Simultaneous analysis of enantiomeric composition of amino acids andN-acetyl-amino acids by enantioselective chromatography." Chirality 13, no. 5 (2001): 231–35. http://dx.doi.org/10.1002/chir.1024.

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Cornick, Nancy A., Bin Yan, Shelton Bank, and Milton J. Allison. "Biosynthesis of amino acids byOxalobacter formigenes: analysis using13C-NMR." Canadian Journal of Microbiology 42, no. 12 (December 1, 1996): 1219–24. http://dx.doi.org/10.1139/m96-157.

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The gram-negative anaerobe Oxalobacter formigenes, grows on oxalate as the principal carbon and energy source, but a small amount of acetate is also required for growth. Experiments were conducted to determine the distribution and the position of label in cellular amino acids from cells grown on [13C]oxalate, [13C]acetate (1-13C, 2-13C, and U-13C), and13CCO3. The labeling pattern (determined with NMR spectroscopy) of amino acids was consistent with their formation through common biosynthetic pathways. The majority of the carbons in the amino acids that are usually derived from pyruvate, oxaloacetate, α-ketoglutarate, 3-phosphoglycerate, and carbon in the aromatic amino acids were labeled by oxalate. Carbon from13CO3was assimilated primarily into amino acids expected to be derived from oxaloacetate and α-ketoglutarate. Approximately 60% of the acetate that was assimilated into amino acids was incorporated as a C2unit into proline, arginine, glutamate, and leucine. The pattern of labeling from acetate in glutamate, arginine, and proline was consistent with acetate incorporation via citrate (si)-synthase and subsequent formation of α-ketoglutarate via the first third of the tricarboxylic acid pathway. Acetate was also assimilated into amino acids derived from pyruvate and oxaloacetate, but results indicated that this incorporation was as single carbon atoms. Based on these findings, cell-free extracts were assayed for several key biosynthetic enzymes. Enzymatic activities found included glutamate dehydrogenase, phosphoenolpyruvate carboxylase, and pyruvate carboxylase. These findings are consistent with proposed biosynthetic mechanisms.Key words: oxalate, carbon flow, carbon assimilation.

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Kumari, Bandana, Ravindra Kumar, Vipin Chauhan, and Manish Kumar. "Comparative functional analysis of proteins containing low-complexity predicted amyloid regions." PeerJ 6 (October 30, 2018): e5823. http://dx.doi.org/10.7717/peerj.5823.

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Background In both prokaryotic and eukaryotic proteins, repeated occurrence of a single or a group of few amino acids are found. These regions are termed as low complexity regions (LCRs). It has been observed that amino acid bias in LCR is directly linked to their uncontrolled expansion and amyloid formation. But a comparative analysis of the behavior of LCR based on their constituent amino acids and their association with amyloidogenic propensity is not available. Methods Firstly we grouped all LCRs on the basis of their composition: homo-polymers, positively charged amino acids, negatively charged amino acids, polar amino acids and hydrophobic amino acids. We analyzed the compositional pattern of LCRs in each group and their propensity to form amyloids. The functional characteristics of proteins containing different groups of LCRs were explored using DAVID. In addition, we also analyzed the classes, pathways and functions of human proteins that form amyloids in LCRs. Results Among homopolymeric LCRs, the most common was Gln repeats. LCRs composed of repeats of Met and aromatic amino acids were amongst the least occurring. The results revealed that LCRs composed of negatively charged and polar amino acids were more common in comparison to LCRs formed by positively charged and hydrophobic amino acids. We also noted that generally proteins with LCRs were involved in transcription but those with Gly repeats were associated to translational activities. Our analysis suggests that proteins in which LCR is composed of hydrophobic residues are more prone toward amyloid formation. We also found that the human proteins with amyloid forming LCRs were generally involved in binding and catalytic activity. Discussion The presented analysis summarizes the most common and least occurring LCRs in proteins. Our results show that though repeats of Gln are the most abundant but Asn repeats make longest stretch of low complexity. The results showed that potential of LCRs to form amyloids varies with their amino acid composition.

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Aponte, José C., Jamie E. Elsila, Jason E. Hein, Jason P. Dworkin, Daniel P. Glavin, Hannah L. McLain, Eric T. Parker, Timothy Cao, Eve L. Berger, and Aaron S. Burton. "Analysis of amino acids, hydroxy acids, and amines in CR chondrites." Meteoritics & Planetary Science 55, no. 11 (November 2020): 2422–39. http://dx.doi.org/10.1111/maps.13586.

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Zhang, Tao, Yan E. Luo, Dai Di Fan, Lei Guo, and Ting Zhen Mu. "Optimizing the Fermentation Process for Recombinant Escherichia coli on Base of Metabolic Flux Analysis of Amino Acids." Advanced Materials Research 550-553 (July 2012): 1055–59. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.1055.

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Amino acids, the basic unit of protein molecules, are closely related to some important biological activities and they affect cell growth and metabolism directly or indirectly. Previous studies showed that adding amino acids can improve the productivity of human-like collagen (HLC). Thus, we analyzed the amino acids metabolism during the fermentation process. The results of metabolic flux analysis of amino acids implied that the cell growth and production of HLC were active as long as the free amino acids in the medium were adequate. This suggested control the concentration of amino acids could improve cell growth and human-like collagen production.

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Jungas, R. L., M. L. Halperin, and J. T. Brosnan. "Quantitative analysis of amino acid oxidation and related gluconeogenesis in humans." Physiological Reviews 72, no. 2 (April 1, 1992): 419–48. http://dx.doi.org/10.1152/physrev.1992.72.2.419.

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Significant gaps remain in our knowledge of the pathways of amino acid catabolism in humans. Further quantitative data describing amino acid metabolism in the kidney are especially needed as are further details concerning the pathways utilized for certain amino acids in liver. Sufficient data do exist to allow a broad picture of the overall process of amino acid oxidation to be developed along with approximate quantitative assessments of the role played by liver, muscle, kidney, and small intestine. Our analysis indicates that amino acids are the major fuel of liver, i.e., their oxidative conversion to glucose accounts for about one-half of the daily oxygen consumption of the liver, and no other fuel contributes nearly so importantly. The daily supply of amino acids provided in the diet cannot be totally oxidized to CO2 in the liver because such a process would provide far more ATP than the liver could utilize. Instead, most amino acids are oxidatively converted to glucose. This results in an overall ATP production during amino acid oxidation very nearly equal to the ATP required to convert amino acid carbon to glucose. Thus gluconeogenesis occurs without either a need for ATP from other fuels or an excessive ATP production that could limit the maximal rate of the process. The net effect of the oxidation of amino acids to glucose in the liver is to make nearly two-thirds of the total energy available from the oxidation of amino acids accessible to peripheral tissues, without necessitating that peripheral tissues synthesize the complex array of enzymes needed to support direct amino acid oxidation. As a balanced mixture of amino acids is oxidized in the liver, nearly all carbon from glucogenic amino acids flows into the mitochondrial aspartate pool and is actively transported out of the mitochondria via the aspartate-glutamate antiport linked to proton entry. In the cytoplasm the aspartate is converted to fumarate utilizing urea cycle enzymes; the fumarate flows via oxaloacetate to PEP and on to glucose. Thus carbon flow through the urea cycle is normally interlinked with gluconeogenic carbon flow because these metabolic pathways share a common step. Liver mitochondria experience a severe nonvolatile acid load during amino acid oxidation. It is suggested that this acid load is alleviated mainly by the respiratory chain proton pump in a form of uncoupled respiration.(ABSTRACT TRUNCATED AT 400 WORDS)

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Wang, Xiao-fang, Yuhao Hu, Ji-Hua Li, Li Zhang, Xiao Gong, and Huang Hui. "Analysis of the basic components and free amino acid composition of pineapple fruit vinegar." E3S Web of Conferences 185 (2020): 04047. http://dx.doi.org/10.1051/e3sconf/202018504047.

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Acetic acid fermentation is an essential step in producing high-quality vinegar. In this study, the alcoholic medium was used as a seed broth for acetic fermentation using Acetobacter aceti as the inoculum for approximately 7 days at 32℃ to obtain 45.87g/L acetic acid. During the Acetic acid fermentation stage, the content of the total polyphenols decreased first and then increased. Based on amino acid analyzer analysis, pineapple vinegar contains 18 kinds of free amino acids. And the contents of sweet and umami free amino acids are the main free amino acids, followed by bitter amino acids.

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Christiansen, Jason K., Joanne E. Hughes, Dennis L. Welker, Beatriz T. Rodríguez, James L. Steele, and Jeff R. Broadbent. "Phenotypic and Genotypic Analysis of Amino Acid Auxotrophy in Lactobacillus helveticus CNRZ 32." Applied and Environmental Microbiology 74, no. 2 (November 9, 2007): 416–23. http://dx.doi.org/10.1128/aem.01174-07.

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ABSTRACT The conversion of amino acids into volatile and nonvolatile compounds by lactic acid bacteria in cheese is thought to represent the rate-limiting step in the development of mature flavor and aroma. Because amino acid breakdown by microbes often entails the reversible action of enzymes involved in biosynthetic pathways, our group investigated the genetics of amino acid biosynthesis in Lactobacillus helveticus CNRZ 32, a commercial cheese flavor adjunct that reduces bitterness and intensifies flavor notes. Most lactic acid bacteria are auxotrophic for several amino acids, and L. helveticus CNRZ 32 requires 14 amino acids. The reconstruction of amino acid biosynthetic pathways from a draft-quality genome sequence for L. helveticus CNRZ 32 revealed that amino acid auxotrophy in this species was due primarily to gene absence rather than point mutations, insertions, or small deletions, with good agreement between gene content and phenotypic amino acid requirements. One exception involved the phenotypic requirement for Asp (or Asn), which genome predictions suggested could be alleviated by citrate catabolism. This prediction was confirmed by the growth of L. helveticus CNRZ 32 after the addition of citrate to a chemically defined medium that lacked Asp and Asn. Genome analysis also predicted that L. helveticus CNRZ 32 possessed ornithine decarboxylase activity and would therefore catalyze the conversion of ornithine to putrescine, a volatile biogenic amine. However, experiments to confirm ornithine decarboxylase activity in L. helveticus CNRZ 32 by the use of several methods were unsuccessful, which indicated that this bacterium likely does not contribute to putrescine production in cheese.

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Shih, V. E., V. Nikiforov, and M. M. Carney. "Acetaminophen metabolite interferes in analysis for amino acids." Clinical Chemistry 31, no. 1 (January 1, 1985): 148. http://dx.doi.org/10.1093/clinchem/31.1.148.

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Żurawicz, Ewa, and Joanna Kałużna-Czaplińska. "Analysis of amino acids in autism spectrum disorders." TrAC Trends in Analytical Chemistry 73 (November 2015): 91–118. http://dx.doi.org/10.1016/j.trac.2015.04.029.

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Halpine, Susana Maria. "ChemInform Abstract: Amino Acids: HPLC Analysis Advanced Techniques." ChemInform 41, no. 26 (June 8, 2010): no. http://dx.doi.org/10.1002/chin.201026280.

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MUSTAFA, A., P. AMAN, R. ANDERSSON, and A. KAMALELDIN. "Analysis of free amino acids in cereal products." Food Chemistry 105, no. 1 (2007): 317–24. http://dx.doi.org/10.1016/j.foodchem.2006.11.044.

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Alvarez-Segura, Tamara, Carolina Camacho-Molinero, José Ramón Torres-Lapasió, and M. Celia García-Alvarez-Coque. "Analysis of amino acids using serially coupled columns." Journal of Separation Science 40, no. 13 (June 22, 2017): 2741–51. http://dx.doi.org/10.1002/jssc.201700334.

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Guo, Dongliang, Li Feng, Taoxiang Zhang, Yaoyao Guo, Yanfen Wang, and Ximing Xu. "PNMAVis: Visual Analysis Tool of Protein Normal Mode for Understanding Cavity Dynamics." Applied Sciences 12, no. 15 (August 7, 2022): 7919. http://dx.doi.org/10.3390/app12157919.

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Molecular cavities play a critical role in our understanding of molecular phenomena. Recently, a number of works on the visual analysis of protein cavity dynamics have been developed to allow experts and users to interactively research dynamic cavity data. However, previous explorations are limited to studying cavity-lining amino acids and they lack a consideration of the impact of the key amino acids, which are far away from the cavity but have an important impact on the cavity. When studying protein amino acids, biochemists use normal mode decomposition to analyze protein changes on a time scale. However, the high-dimensional parameter space generated via decomposition is too large to be analyzed in detail. We present a novel approach that combines cavity characterization and normal mode analysis (NMA) for cavity dynamics analysis to reduce and explore this vast space through interactive visualization. PNMAVis can analyze whether direct factors (cavity-lining amino acids) or indirect factors (key amino acids) affect cavity changes, through multiple linked 2D and 3D views. The visual analysis method we proposed is based on close cooperation with domain experts, aiming to meet their needs to explore the relationship between cavity stability and cavity-lining amino acids fluctuations and key amino acids fluctuations as much as possible, and also to help domain experts identify potential allosteric residues. The effectiveness of our new method is demonstrated by the case study conducted by cooperative protein experts on a biological field case and an open normal mode data set.

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Gehrke, Charles W., Paul R. Rexroad, Robert M. Schisla, Joseph S. Absheer, and Robert W. Zumwalt. "Quantitative Analysis of Cystine, Methionine, Lysine, and Nine Other Amino Acids by a Single Oxidation-4 Hour Hydrolysis Method." Journal of AOAC INTERNATIONAL 70, no. 1 (January 1, 1987): 171–74. http://dx.doi.org/10.1093/jaoac/70.1.171.

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Abstract The sulfur-containing amino acids cystine and methionine play important roles in animal, especially avian, nutrition. Because these ndror-containing amino acids are destroyed to varying extents by 6N HC1 hydrolysis, oxidation and hydrolysis of cystine to cysteic add and methionine to methionine sulfone have been widely used for determination of cystine and methionine. Lysine is considered the next limiting amino acid after the sulfur amino acids in poultry •ntrition; therefore, determination of the amino acid content of rations focuses first on these 3 amino acids. The objective of this investigation was to establish whether lysine and other amino acids could be accurately determined in proteinaceous materials which had mdergone performic acid oxidation. To perform this evaluation, lysine was determined in a variety of protein-containing materials both with and without performic acid oxidation. Performic acid oxidation followed by 6N HC1 hydrolysis at 145°C for 4 h allows accurate measurement of 3 amino acids especially important to poultry nutrition, cystine, methionine, and lysine, in a single preoxidized hydralysate; this method can be extended to another 9 protein amino adds.

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Ulusoy, Songül, Halil Ibrahim Ulusoy, Daniel Pleissner, and Niels Thomas Eriksen. "Nitrosation and analysis of amino acid derivatives by isocratic HPLC." RSC Advances 6, no. 16 (2016): 13120–28. http://dx.doi.org/10.1039/c5ra25854e.

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Amino acids are transformed by nitrosation with dinitrogen trioxide into their corresponding α-hydroxy acids, which are separated and analysed by HPLC, and used to quantify the original amino acid concentration in samples.

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Jiang, Long, Haiyan Yu, Dianyuan Chen, Xiaoming Yu, Hui Xu, Xue Ma, Bo Sun, and Xin Mu Fan. "Detection and analysis of free amino acids in waxy maize DH lines by HPLC in north-east China." Bangladesh Journal of Botany 48, no. 4 (December 31, 2019): 989–1000. http://dx.doi.org/10.3329/bjb.v48i4.49039.

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Composition of free amino acid in waxy maize DH lines was analysed and the nutritional quality of waxy maize germplasm resources was evaluated by o-phthaladehyde (OPA) pre-column derivatization reversed-phase high performance liquid chromatography (HPLC). Results obtained showed that there were at least 14 kinds of free amino acids, DH57 line had the highest (25.185 mg/g), and DH21 line had the lowest (6.203 mg/g) and the average was 12.226 mg/g. The contents of essential amino acids varied from 2.59 to 14.09 mg/g, accounting for 29.55 - 75.64% of the total free amino acids. The quality of free amino acids was evaluated by comprehensive indices with principal component analysis and the first top three DH lines were DH57, DH59 and DH55. The contents of free amino acids in 60 waxy maize DH lines had obvious genetic diversity. As to the free amino acid content, the amino acids quality of DH57, DH59 and DH55 were the best, while DH21 was the worst. Results provide a theoretical guidance for the cultivation of new varieties of waxy maize with good quality.

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Jim, Susan, Vicky Jones, Stanley H. Ambrose, and Richard P. Evershed. "Quantifying dietary macronutrient sources of carbon for bone collagen biosynthesis using natural abundance stable carbon isotope analysis." British Journal of Nutrition 95, no. 6 (June 2006): 1055–62. http://dx.doi.org/10.1079/bjn20051685.

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The diets of laboratory rats were isotopically and nutritionally manipulated using purifiedC3 and/or C4 macronutrients to investigate the routing of dietary carbonto bone collagen biosynthesis. Diets were formulated with purified proteins, carbohydrates andlipids of defined composition and natural abundance stable isotope ratios. Bulk protein and constituent amino acid δ13C values determined for whole diet and bone collagen provided the basis for assessing isotopic fractionation and estimating the degree of routing versus synthesis de novo of essential, non-essential and conditionally indispensable amino acids. Essential and conditionally indispensable amino acids were shown to be routed from diet to collagen with little isotopic fractionation whereas non-essential amino acids differed by up to 20‰. Mathematical modelling of the relationships between macronutrient and tissue δ13C values provided qualitative and quantitative insights into the metabolic and energetic controls on bone collagen biosynthesis. Essential amino acids comprise 21·7% of the carbon in collagen, defining the minimum amount of dietary carbon routing. Estimates of 42 and 28% routing were shown for the non-essential amino acids, glycine and aspartate, respectively. In total, the routing of non-essential and conditionally indispensable amino acids was estimated to equal 29·6% of the carbon in collagen. When the contribution of carbon from the essential amino acids is also considered, we arrive at an overall minimum estimate of 51·3% routing of dietary amino acid carbon into bone collagen.

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Revanappa, Santhosh Kumar, Isha Soni, Manjappa Siddalinganahalli, Gururaj Kudur Jayaprakash, Roberto Flores-Moreno, and Chandrashekar Bananakere Nanjegowda. "A Fukui Analysis of an Arginine-Modified Carbon Surface for the Electrochemical Sensing of Dopamine." Materials 15, no. 18 (September 13, 2022): 6337. http://dx.doi.org/10.3390/ma15186337.

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Amino acid-modified carbon interfaces have huge applications in developing electrochemical sensing applications. Earlier reports suggested that the amine group of amino acids acted as an oxidation center at the amino acid-modified electrode interface. It was interesting to locate the oxidation centers of amino acids in the presence of guanidine. In the present work, we modeled the arginine-modified carbon interface and utilized frontier molecular orbitals and analytical Fukui functions based on the first principle study computations to analyze arginine-modified CPE (AMCPE) at a molecular level. The frontier molecular orbital and analytical Fukui results suggest that the guanidine (oxidation) and carboxylic acid (reduction) groups of arginine act as additional electron transfer sites on the AMCPE surface. To support the theoretical observations, we prepared the arginine-modified CPE (AMCPE) for the cyclic voltammetric sensing of dopamine (DA). The AMCPE showed excellent performance in detecting DA in blood serum samples.

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Daly, Rebecca A., and C. Phoebe Lostroh. "Genetic analysis of theSalmonellatranscription factor HilA." Canadian Journal of Microbiology 54, no. 10 (October 2008): 854–60. http://dx.doi.org/10.1139/w08-075.

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HilA, a Salmonella transcription factor, activates the invF-1 and prgH promoters through binding to the HilA box, which contains 2 copies of a TTKHAT motif separated by a T centered at –45 relative to the start sites of transcription. The N-terminal 112 amino acids of HilA are similar to winged helix-turn-helix DNA binding/transcription activation domains (wHTH DBDs). The remaining 441 amino acids are not similar in sequence to any other well-characterized transcription factors. Here, we report that the wHTH DBD is essential for activation of both promoters, but amino acids 113–554 are only required for normal activation of invF-1. Some alanine substitutions in the putative α loop, which connects the recognition and positioning helices in wHTH DBDs, cause a loss-of-activation phenotype. A hilA allele encoding a protein with an alanine substituted for arginine at position 71 in the α loop has a loss-of-activation defect exclusively at the prgH promoter. The results suggest distinct roles for one or more domains formed by amino acids 113–554 and for arginine 71 in activation of the 2 promoters.

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Ito, Len, Kentaro Shiraki, and Hiroshi Yamaguchi. "Comparative analysis of amino acids and amino-acid derivatives in protein crystallization." Acta Crystallographica Section F Structural Biology and Crystallization Communications 66, no. 6 (May 27, 2010): 744–49. http://dx.doi.org/10.1107/s1744309110013710.

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Zhang, Lin, and Mark A. Altabet. "Amino-group-specific natural abundance nitrogen isotope ratio analysis in amino acids." Rapid Communications in Mass Spectrometry 22, no. 4 (February 28, 2008): 559–66. http://dx.doi.org/10.1002/rcm.3393.

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Saragih, Raskita, Ermiziar Tamizi, and Shinta Leonita. "AMINO ACID PROFILE ANALYSIS OF RED AND GREEN MELINJO PEELS TEA." Jurnal Pangan dan Agroindustri 9, no. 4 (October 31, 2021): 208–15. http://dx.doi.org/10.21776/ub.jpa.2021.009.04.2.

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The study aims to analyze the profile of non-essential and essential amino acids in the peels and herbal tea products made from red and green melinjo peels. The processing of melinjo seeds into chips in Pandeglang Regency in Banten Provence, produces large amounts of melinjo peels waste. The processed tea from red and green melinjo peels contains polyphenol compounds, antioxidants, protein and amino acids that are good for health. The processing stages of the melinjo peel tea by sorting the peels for red and green melinjo peels, then washed, made them into thin slices, and dried using an oven blower at 65oC of temperature for 4 hours. Both green and red melinjo peels tea were analyzed for the amino acid profile using the UPLC method. Based on the results of the analysis, it was found that the amino acid content of melinjo peels and melinjo peels tea, both green and red, consisted of 7 non-essential amino acids and 8 essential amino acids. L-glutamic acid and L-aspartic acid are the highest amino acid components which can give melinjo peels tea a characteristic aroma and taste.

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Bidlingmeyer, Brian A., Steven A. Cohen, Thomas L. Tarvin, and Beverly Frost. "A New, Rapid, High-Sensitivity Analysis of Amino Acids in Food Type Samples." Journal of AOAC INTERNATIONAL 70, no. 2 (March 1, 1987): 241–47. http://dx.doi.org/10.1093/jaoac/70.2.241.

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Abstract A new approach to the analysis of free amino acids and amino acids from hydrolyzed foods is described. The method is based on reaction of the free amino acids with phenylisothiocyanate to form stable derivatives which are subsequently separated by liquid chromatography. Sample preparation procedures are described and results are compared with conventional ion exchange results. Reproducibility of the new method has been determined on a typical food type sample.

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Joshi, Vijay, Padma Nimmakayala, Qiushuo Song, Venkata Abburi, Purushothaman Natarajan, Amnon Levi, Kevin Crosby, and Umesh K. Reddy. "Genome-wide association study and population structure analysis of seed-bound amino acids and total protein in watermelon." PeerJ 9 (October 19, 2021): e12343. http://dx.doi.org/10.7717/peerj.12343.

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Background Watermelon seeds are a powerhouse of value-added traits such as proteins, free amino acids, vitamins, and essential minerals, offering a paleo-friendly dietary option. Despite the availability of substantial genetic variation, there is no sufficient information on the natural variation in seed-bound amino acids or proteins across the watermelon germplasm. This study aimed to analyze the natural variation in watermelon seed amino acids and total protein and explore underpinning genetic loci by genome-wide association study (GWAS). Methods The study evaluated the distribution of seed-bound free amino acids and total protein in 211 watermelon accessions of Citrullus spp, including 154 of Citrullus lanatus, 54 of Citrullus mucosospermus (egusi) and three of Citrullus amarus. We used the GWAS approach to associate seed phenotypes with 11,456 single nucleotide polymorphisms (SNPs) generated by genotyping-by-sequencing (GBS). Results Our results demonstrate a significant natural variation in different free amino acids and total protein content across accessions and geographic regions. The accessions with high protein content and proportion of essential amino acids warrant its use for value-added benefits in the food and feed industries via biofortification. The GWAS analysis identified 188 SNPs coinciding with 167 candidate genes associated with watermelon seed-bound amino acids and total protein. Clustering of SNPs associated with individual amino acids found by principal component analysis was independent of the speciation or cultivar groups and was not selected during the domestication of sweet watermelon. The identified candidate genes were involved in metabolic pathways associated with amino acid metabolism, such as Argininosuccinate synthase, explaining 7% of the variation in arginine content, which validate their functional relevance and potential for marker-assisted analysis selection. This study provides a platform for exploring potential gene loci involved in seed-bound amino acids metabolism, useful in genetic analysis and development of watermelon varieties with superior seed nutritional values.

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Darragh, Alison J., and Paul J. Moughan. "The Effect of Hydrolysis Time on Amino Acid Analysis." Journal of AOAC INTERNATIONAL 88, no. 3 (May 1, 2005): 888–93. http://dx.doi.org/10.1093/jaoac/88.3.888.

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Abstract Determining the amino acid content of a protein involves the hydrolysis of that protein, usually in acid, until the protein-bound amino acids are released and made available for detection. Both the variability in the ease of peptide bond cleavage and differences in the acid stability of certain amino acids can significantly affect determination of a protein's amino acid content. By using multiple hydrolysis intervals, a greater degree of accuracy can be obtained in amino acid analysis. Correction factors derived by linear extrapolation of serial hydrolysis data are currently used. Compartmental modeling of the simultaneous hydrolysis (yield) and degradation (decay) of amino acids by nonlinear multiple regression of serial hydrolysis data has also been validated and applied to determine the amino acid composition of various biological samples, including egg-white lysozyme, human milk protein, and hair. Implicit in the routine application of serial hydrolysis in amino acid analysis, however, is an understanding that correction factors, derived either linearly or through the more accurate nonlinear multiple regression approach, need to be determined for individual proteins rather than be applied uniformly across all protein types.

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KUSUDA, Kazuyuki, Takayasu KOBAYASHI, Shoko IKEDA, Motoko OHNISHI, Naoki CHIDA, Yuchio YANAGAWA, Ryuzaburo SHINEHA, et al. "Mutational analysis of the domain structure of mouse protein phosphatase 2Cβ." Biochemical Journal 332, no. 1 (May 15, 1998): 243–50. http://dx.doi.org/10.1042/bj3320243.

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The structures of five distinct isoforms of mammalian protein phosphatase 2Cβ (PP2Cβ-1, -2, -3, -4 and -5) have previously been found to differ only at their C-terminal regions. In the present study, we performed mutational analysis of recombinant mouse PP2Cβ-1 to determine the functional domains of the molecule and elucidate the biochemical significance of the structural differences in the isoforms. Differences in affinity for [32P]phosphohistone but not for [32P]phosphocasein were observed among the five PP2Cβ isoforms. Deletion of 12 amino acids from the C-terminal end, which form a unique sequence for PP2Cβ-1, caused a 35% loss of activity against [32P]phosphohistone but no loss of activity against [32P]phosphocasein. Deletion of up to 78 amino acids from this end did not cause any further alteration in activity, whereas deletion of 100 amino acids totally eliminated the activity against both [32P]phosphohistone and [32P]phosphocasein. On the other hand, deletion of 11 amino acids from the N-terminal end caused a 97% loss of enzyme activity, and further deletions caused a total loss of activity. Substitution of any of the six specific amino acids among 16 tested in this study, which were located among the 250 N-terminal residues, caused 98–100% loss of enzyme activity. Among these amino acids, three (Glu-38, -60 and -243) have recently been reported to be essential for the binding of metal ions in the catalytic site of the PP2C molecule [Das, Helps, Cohen and Barford (1996) EMBO J. 15, 6798–6809]. These observations indicate that PP2Cβ is composed of at least two distinct functional domains, an N-terminal catalytic domain of about 310 amino acids and the remaining C-terminal domain, which is involved in determination of substrate specificity.

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Rutherfurd, Shane M., and Paul J. Moughan. "Available versus digestible dietary amino acids." British Journal of Nutrition 108, S2 (August 2012): S298—S305. http://dx.doi.org/10.1017/s0007114512002528.

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Available amino acids are those absorbed from the gastrointestinal tract in a form suitable for body protein synthesis. True ileal digestible amino acids are determined based on the difference between dietary amino acid intake and unabsorbed dietary amino acids at the terminal ileum. The accuracy of ileal digestible amino acid estimates for predicting available amino acid content depends on several factors, including the accuracy of the amino acid analysis procedure. In heat processed foods, lysine can react with compounds to form nutritionally unavailable derivatives that are unstable during the hydrochloric acid hydrolysis step of amino acid analysis and can revert back to lysine causing an overestimate of available lysine. Recently, the true ileal digestible reactive (available) lysine assay based on guanidination has provided a means of accurately determining available lysine in processed foods. Methionine can be oxidised during processing to form methionine sulphoxide and methionine sulphone and cysteine oxidised to cysteic acid. Methionine sulphoxide, but not methionine sulphone or cysteic acid, is partially nutritionally available in some species of animal. Currently, methionine and cysteine are determined as methionine sulphone and cysteic acid respectively after quantitative oxidation prior to acid hydrolysis. Consequently, methionine and cysteine are overestimated if methionine sulphone or cysteic acid are present in the original material. Overall, given the problems associated with the analysis of some amino acids in processed foodstuffs, the available amino acid content may not always be accurately predicted by true ileal amino acid digestibility estimates. For such amino acids specific analytical strategies may be required.

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Hasemann, C. A., and J. D. Capra. "Mutational analysis of the cross-reactive idiotype of the A strain mouse." Journal of Immunology 147, no. 9 (November 1, 1991): 3170–79. http://dx.doi.org/10.4049/jimmunol.147.9.3170.

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Abstract The elucidation of the structural basis for expression of the cross-reactive Id of the A strain mouse (CRIA) in response to the hapten p-azophenylarsonate has been the object of considerable research effort. Most conclusions regarding the amino acids involved in Id expression have been inferential, based on comparisons of amino acid sequences, chain recombination experiments, or chemical modification of particular amino acids. To more rigorously designate the amino acids critical to the phenotype of the CRIA, a system for the expression and directed mutation of antibody molecules was developed. Based on the baculovirus expression of foreign proteins in cultured insect cells, functional antibodies can be produced at very high levels in vitro. By the process of oligonucleotide-directed mutagenesis, a series of specific amino acid changes were introduced into both the H and L chains of a prototype CRIA expressing antibody molecule. Analysis of the gain or loss of polyclonal Id and each of several monoclonal idiotopes has allowed us to identify more precisely the amino acids responsible for expression of the CRIA. Thus we have shown that expression of the CRIA is equally dependent on amino acids in the second and third CDR of the H chain. Furthermore, the idiotopes studied surround the Ag-binding site and clearly involve multiple interactions in several of the L and H chain CDR.

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Bicudo, Álvaro José de Almeida, Luis Fernando Batista Pinto, and José Eurico Possebon Cyrino. "Clustering of ingredients with amino acid composition similar to the nutritional requirement of Nile tilapia." Scientia Agricola 67, no. 5 (October 2010): 517–23. http://dx.doi.org/10.1590/s0103-90162010000500004.

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The search for balanced diets, which may elicit improved growth of fish, requires appropriate selection of available protein sources. This study aims at clustering feedstuffs according to amino acid profile, determining which ones show essential amino acids (EAA) profiles closer to the ideal dietary amino acids requirements of Nile tilapia (Oreochromis niloticus), and studying the relationship among amino acids feedstuffs groups. Tabled data on EAA more cystine and tyrosine, in relation to lysine contents, of 40 feedstuffs ordinarily used to formulate fish diets were studied. Feedstuffs were grouped according to amino acids profile by cluster analysis of Euclidean distances. The principal components analysis was used to determine the relationship among amino acids in each feedstuff group. Three groups of ingredients were parted and two ingredients, low tannin sorghum and corn gluten meal 60%, did not go with any group. Dietary amino acids requirements of Nile tilapia were similar to the amino acid profile of 22 feedstuffs. The principal component analysis explained with three principal components more than 75% of total variance of amino acids in three feedstuff groups. Therefore, until additional, detailed information on amino acids availability of different ingredients is consolidated, total amino acids profiles will continue to be important information to select and use conventional or surrogate ingredients for formulating and processing feeds for tilapia.

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Journal articles on the topic 'Amino acids – Analysis'

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