Log in

Relevant bibliographies by topics / Enzyme activity determination / Journal articles

Journal articles on the topic 'Enzyme activity determination'

To see the other types of publications on this topic, follow the link: Enzyme activity determination.

Author: Grafiati

Published: 10 December 2022

Last updated: 29 January 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 journal articles for your research on the topic 'Enzyme activity determination.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

Holmes, M. J., T. Southworth, N. G. Watson, and M. J. W. Povey. "Enzyme activity determination using ultrasound." Journal of Physics: Conference Series 498 (April 1, 2014): 012003. http://dx.doi.org/10.1088/1742-6596/498/1/012003.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Zharare, Tafadzwa, and Rumbidzai Mangoyi. "Isolation and Activity Determination of Enzyme Phosphatase Secreted by Aspergillus niger." International Annals of Science 9, no. 1 (November 16, 2019): 41–45. http://dx.doi.org/10.21467/ias.9.1.41-45.

Full text

Abstract:

The use of enzymes on industrial scale saves a lot of energy and avoids pollution, thus holding a promise for green and economically sustainable alternative strategies in industrial transformations. Generally, the fungi Aspergillus niger secretes enzymes which can be used in different industries. Thus, coming up with these enzymes in large amounts will definitely result in reduced costs encountered in importing them for industrial use. This study focussed on isolation and activity determination of an enzyme phosphatase secreted by Aspergillus niger. This enzyme can be of great importance in molecular biology industries, particularly for recombinant DNA technology. For this study, pure cultures of Aspergillus niger were used. Aspergillus niger was resuscitated on potato dextrose agar and then subcultured in Adam’s medium, a medium specific for the production of phosphatase. Cells were centrifuged and the filtrate was collected whilst the residue was discarded. The filtrate was expected to contain the crude enzyme phosphatase since Aspergillus niger secretes the extracellular enzyme into the medium. Disodium phenyl phosphate was used as a substrate for the determination of the phosphatase activity. The enzyme activity was determined spectrophotometrically by reading absorbance of phenol formed in the presence of enzyme and the substrate. The concentration of phenol liberated was then used to calculate the enzyme activity expressed in King Armstrong Units (KAU). Further work on enzyme activity determination was done by varying enzyme and substrate concentrations. Results showed that the isolated alkaline phosphatase had activity of 4.0 KAU and 4.5 KAU at 25 ºC and 37 ºC respectively. Acidic phosphatase had activity of 5 KAU and 7 KAU at 25 ºC and 37 ºC respectively. Rate of activity increased upon increasing enzyme concentration and substrate. Thus, Aspergillus niger produces the enzyme phosphatase, however, there is need to induce the production of these enzymes for industrial use.

APA, Harvard, Vancouver, ISO, and other styles

3

BENEŠOVÁ, Karolína, Sylvie BĚLÁKOVÁ, Renata MIKULÍKOVÁ, and Zdeněk SVOBODA. "Determination of proteolytic enzyme activity during malting." Kvasny Prumysl 64, no. 6 (December 14, 2018): 318–22. http://dx.doi.org/10.18832/kp201838.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

MIYAUCHI, Kouhei, Kunio SAWAMURA, Eiichi TAMIYA, and Isao KARUBE. "Determination of dextranase activity using enzyme sensor." NIPPON KAGAKU KAISHI, no. 3 (1987): 512–17. http://dx.doi.org/10.1246/nikkashi.1987.512.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Ionescu, Cătălina, Georgeta Ciobanu, Ioana-Cristina Ispas, Anca Moanță, Mădălina Drăgoi, and Simona-Cristina Rizea. "DETERMINATION OF Α-MANNOSIDASE ENZYMATIC ACTIVITY." Annals of the University of Craiova, Series Chemistry 27, no. 2 (December 2021): 75–82. http://dx.doi.org/10.52846/auc.chem.2021.2.08.

Full text

Abstract:

"α-mannosidase is a hydrolytic enzyme that cleaves α-glycosidic bonds of mannopyranoside derivatives. In this study, the enzyme activity and the specific activity of α-mannosidase have been determined using the p-nitrophenyl-alpha-Dmannopyranoside hydrolysis assay."

APA, Harvard, Vancouver, ISO, and other styles

6

Ionescu, Cătălina, Georgeta Ciobanu, Ioana-Cristina Ispas, Anca Moanță, Mădălina Drăgoi, and Simona-Cristina Rizea. "DETERMINATION OF Α-MANNOSIDASE ENZYMATIC ACTIVITY." Annals of the University of Craiova, Series Chemistry 27, no. 2 (December 2021): 75–82. http://dx.doi.org/10.52846/aucchem.2021.2.08.

Full text

Abstract:

"α-mannosidase is a hydrolytic enzyme that cleaves α-glycosidic bonds of mannopyranoside derivatives. In this study, the enzyme activity and the specific activity of α-mannosidase have been determined using the p-nitrophenyl-alpha-Dmannopyranoside hydrolysis assay."

APA, Harvard, Vancouver, ISO, and other styles

7

Peterson, Michelle E., Roy M. Daniel, Michael J. Danson, and Robert Eisenthal. "The dependence of enzyme activity on temperature: determination and validation of parameters." Biochemical Journal 402, no. 2 (February 12, 2007): 331–37. http://dx.doi.org/10.1042/bj20061143.

Full text

Abstract:

Traditionally, the dependence of enzyme activity on temperature has been described by a model consisting of two processes: the catalytic reaction defined by ΔGDaggercat, and irreversible inactivation defined by ΔGDaggerinact. However, such a model does not account for the observed temperature-dependent behaviour of enzymes, and a new model has been developed and validated. This model (the Equilibrium Model) describes a new mechanism by which enzymes lose activity at high temperatures, by including an inactive form of the enzyme (Einact) that is in reversible equilibrium with the active form (Eact); it is the inactive form that undergoes irreversible thermal inactivation to the thermally denatured state. This equilibrium is described by an equilibrium constant whose temperature-dependence is characterized in terms of the enthalpy of the equilibrium, ΔHeq, and a new thermal parameter, Teq, which is the temperature at which the concentrations of Eact and Einact are equal; Teq may therefore be regarded as the thermal equivalent of Km. Characterization of an enzyme with respect to its temperature-dependent behaviour must therefore include a determination of these intrinsic properties. The Equilibrium Model has major implications for enzymology, biotechnology and understanding the evolution of enzymes. The present study presents a new direct data-fitting method based on fitting progress curves directly to the Equilibrium Model, and assesses the robustness of this procedure and the effect of assay data on the accurate determination of Teq and its associated parameters. It also describes simpler experimental methods for their determination than have been previously available, including those required for the application of the Equilibrium Model to non-ideal enzyme reactions.

APA, Harvard, Vancouver, ISO, and other styles

8

Rawski, Rafał Ireneusz, Przemysław Tomasz Sanecki, and Jan Kalembkiewicz. "Units and Methods of Proteolytic Activity Determination." Current Pharmaceutical Analysis 16, no. 6 (July 1, 2020): 661–70. http://dx.doi.org/10.2174/1573412915666190304151224.

Full text

Abstract:

Background: In order to organize and give a better understanding of the existing population of protease activity units together with their respective methods of enzymatic activity assessment, there is a need of their clear classification system. Results and Conclusion: The following system has been proposed: Enzyme Centered Units (ECU) equivalent to Enzyme Process Unit notation; Protein Centered Units (PCU) equivalent to Protein Process Unit notation; Legal Authority and Enzyme Centered Units (LAECU) equivalent to Enzyme Centered Units system additionally related to a legal authority or an organization. The suitable ways for the mutual conversion of commonly used units and their conversion into the standard SI units have been included. A convenient gravity/spectrophotometer test of proteolytic activity with the use of three protein types has also been proposed. The test gives high degree of confidence of the experimental determination for a wide spectrum of protease activity in samples of plant origin. The whole paper allows both theoretical and practical orientation in the range of different proteolytic activity units as well as in the methods of their determination.

APA, Harvard, Vancouver, ISO, and other styles

9

ZEMEK, J., and V. HOMOĽOVÁ. "Enzyme activity of malt determination by direct methods." Kvasny Prumysl 39, no. 9 (September 1, 1993): 261–63. http://dx.doi.org/10.18832/kp1993018.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Terra, Gleysson De Paula, Marcus Vinícius De Farias, Marcello Garcia Trevisan, and Jerusa Simone Garcia. "Evaluation of pancreatin stability through enzyme activity determination." Acta Pharmaceutica 66, no. 3 (September 1, 2016): 423–31. http://dx.doi.org/10.1515/acph-2016-0037.

Full text

Abstract:

Abstract Pancreatin is a biotechnological product containing an enzyme complex, obtained from porcine pancreas, that is employed in treating pancreatic diseases. Experiments regarding the stability of the pharmaceutical formulation containing pancreatin were performed using standard binary mixtures with 6 excipients in a 1:1 ratio (m/m) and a commercial formulation. To accomplish these goals, samples were stored for 1, 3 and 6 months at 40 ± 1 °C and 75 ± 5 % relative humidity (RH) and 40 ± 1 °C and 0 % RH. Stress testing was also performed. All samples were analyzed to evaluate the α-amylase, lipase and protease activities through UV/Vis spectrophotometry. The results revealed that the excipient proprieties and the storage conditions affected enzyme stability. Humidity was a strong influencing factor in the reduction of α-amylase and protease activities. Stress testing indicated that pH 9.0 and UV light did not induce substantial alterations in enzyme activity.

APA, Harvard, Vancouver, ISO, and other styles

11

Van Lente, F., and M. Pepoy. "Coupled-enzyme determination of catalase activity in erythrocytes." Clinical Chemistry 36, no. 7 (July 1, 1990): 1339–43. http://dx.doi.org/10.1093/clinchem/36.7.1339.

Full text

Abstract:

Abstract This coupled-enzyme method for determining the activity of catalase (EC 1.11.1.6) in erythrocyte lysates is based on measuring the absorbance at 340 nm of NADH produced from the peroxidic reaction between ethanol, hydrogen peroxide, and catalase. Hydrogen peroxide is produced as a substrate in situ from the oxidation of glucose catalyzed by glucose oxidase (EC 1.1.3.4). Catalase oxidizes ethanol to acetaldehyde in the presence of hydrogen peroxide. Acetaldehyde is then oxidized by aldehyde dehydrogenase (EC 1.2.1.5) to produce acetate with concomitant conversion of NAD+ to NADH. The reaction did not follow strict zero-order kinetics; enzyme activity was quantified by using initial rates and standards prepared from purified catalase. The method demonstrated within-run and between-run CVs of 1.0% to 2.9% and 2.4% to 3.3%, respectively. This semiautomated method correlated well (r = 0.92) with the more tedious manual method involving measurement at 240 nm.

APA, Harvard, Vancouver, ISO, and other styles

12

Shin, Joong-Gon, Tae Sun Kang, Hyun Sub Cheong, Hee Jung Shin, Hyun Joo Park, Han Sung Na, Hyoung Doo Shin, and Myeon Woo Chung. "Determination of DPYD Enzyme Activity in Korean Population." Therapeutic Drug Monitoring 37, no. 2 (April 2015): 147–51. http://dx.doi.org/10.1097/ftd.0000000000000109.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Elbrecht, A., and R. Smith. "Aromatase enzyme activity and sex determination in chickens." Science 255, no. 5043 (January 24, 1992): 467–70. http://dx.doi.org/10.1126/science.1734525.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Walker, JRL. "Spectrophotometric determination of enzyme activity: alcohol dehydrogenase (ADH)." Biochemical Education 20, no. 1 (January 1992): 42–43. http://dx.doi.org/10.1016/0307-4412(92)90021-d.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Daniel, R. M., M. J. Danson, R. Eisenthal, C. K. Lee, and M. E. Peterson. "New parameters controlling the effect of temperature on enzyme activity." Biochemical Society Transactions 35, no. 6 (November 23, 2007): 1543–46. http://dx.doi.org/10.1042/bst0351543.

Full text

Abstract:

Arising from careful measurements of the thermal behaviour of enzymes, a new model, the Equilibrium Model, has been developed to explain more fully the effects of temperature on enzymes. The model describes the effect of temperature on enzyme activity in terms of a rapidly reversible active–inactive (but not denatured) transition, revealing an additional and reversible mechanism for enzyme activity loss in addition to irreversible thermal inactivation at high temperatures. Two new thermal parameters, Teq and ΔHeq, describe the active–inactive transition, and enable a complete description of the effect of temperature on enzyme activity. We describe here the Model and its fit to experimental data, methods for the determination of the Equilibrium Model parameters, and the implications of the Model for the environmental adaptation and evolution of enzymes, and for biotechnology.

APA, Harvard, Vancouver, ISO, and other styles

16

Tan, W. H., and E. S. Yeung. "Simultaneous Determination of Enzyme Activity and Enzyme Quantity in Single Human Erythrocytes." Analytical Biochemistry 226, no. 1 (March 1995): 74–79. http://dx.doi.org/10.1006/abio.1995.1193.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Rejeb, Ines Ben, Jeannette Ben Hamida, and Mohamed Gargouri. "Coupled-enzyme system for the determination of lipase activity." Biotechnology Letters 26, no. 16 (August 2004): 1273–76. http://dx.doi.org/10.1023/b:bile.0000044917.68640.c4.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Ikarashi, Yasushi, Toshikazu Hada, E. Leong Way, and Yuji Maruyama. "Determination of succinylcholine hydrolytic enzyme activity in human plasma." Journal of Chromatography B: Biomedical Sciences and Applications 533 (January 1990): 23–33. http://dx.doi.org/10.1016/s0378-4347(00)82184-2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Glatz, Z., P. Bouchal, O. Janiczek, M. Mandl, and P. Česková. "Determination of rhodanese enzyme activity by capillary zone electrophoresis." Journal of Chromatography A 838, no. 1-2 (April 1999): 139–48. http://dx.doi.org/10.1016/s0021-9673(98)00972-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Ikarashi, Y., T. Hada, K. Itoh, E. L. Way, and Y. Maruyama. "Determination off succinylcholine hydrolytic enzyme activity in human plasma." European Journal of Pharmacology 183, no. 4 (July 1990): 1373. http://dx.doi.org/10.1016/0014-2999(90)94498-m.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Welling, Gjalt W., Albert Jan Scheffer, and Sytske Welling-Wester. "Determination of enzyme activity by high-performance liquid chromatography." Journal of Chromatography B: Biomedical Sciences and Applications 659, no. 1-2 (September 1994): 209–25. http://dx.doi.org/10.1016/0378-4347(94)00154-5.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Godovalov, A. P., M. V. Yakovlev, and I. I. Zadorina. "MICROTEST FOR THE DETERMINATION OF THE AMYLOLYTIC ACTIVITY OF SALIVA ALPHA-AMYLASE." Russian Journal of Dentistry 23, no. 3-4 (August 15, 2019): 115–17. http://dx.doi.org/10.18821/1728-2802-2019-23-3-4-115-117.

Full text

Abstract:

It is known that the concentration of alpha-amylase in saliva can determine its catalytic activity, the decrease of which occurs during various pathological processes in the oral cavity. The overwhelming number of methods for determining the catalytic activity of enzymes involve the use of a large volume of reagents and samples, which makes it difficult to study saliva in large groups. The purpose of the study is to evaluate the possibility of using the microvariation of the reaction to determine the activity of saliva alpha-amylase, as well as to analyze the dependence of the enzyme activity on its concentration. Materials and methods. Saliva was obtained from 15 people with intact periodontal disease and the dentition, without somatic pathology. For in vitro studies, alpha-amylase solutions were prepared with an enzyme concentration of 10; five; 2.5; one; 0.5 and 0.25 mg / ml ex tempore. To save samples and reagents, the volume of the reaction participants was proportionally reduced. The further analysis procedure was carried out according to the instructions of the manufacturer of the «AMYLASE-VITAL» reagent kit to determine the activity of alpha-amylase. Statistical analysis of the results was performed using the Student’s t-test in the program Statistica 7.0. Results. The comparability of the results of determining the activity of alpha-amylase using the classical and microplate variants of the reaction is shown. With an increase in alpha-amylase concentration from 0 to 2.5 mg / ml, a directly proportional increase in enzyme activity is observed. In the case of an increase in the concentration of alpha-amylase above 2.5 mg / ml, a decrease in its activity is shown, which may be due to the precipitation of a part of the enzyme. The activity of the enzyme in saliva of practically healthy individuals using the microvariation of the reaction was 528.6 ± 2.4 U / l. In conclusion the use of a microvariant of the reaction for determining the activity of alpha-amylase may be justified for a large number of subjects. A linear dependence of the enzyme activity on its concentration in the range of 0-2.5 mg / ml is shown.

APA, Harvard, Vancouver, ISO, and other styles

23

Avdiyuk, K. V., V. A. Ivanytsia, and L. D. Varbanets. "Screening of Enzyme Producers with Keratinase Activity among Marine Actinobacteria." Mikrobiolohichnyi Zhurnal 83, no. 2 (April 17, 2021): 12–19. http://dx.doi.org/10.15407/microbiolj83.02.012.

Full text

Abstract:

About 2 million tons of feathers are produced annually around the world as a by-product of poultry farming. Due to the lack of funds and the complexity of processing, they have become one of the main environmental pollutants. The biodegradation of feathers by keratinolytic microorganisms has proven to be an effective, environmentally friendly and cost-effective method of bioconverting feather waste into a nutritious, balanced and easily digestible product that contains free amino acids, peptides and ammonium ions. Aim. To investigate the ability of marine actinobacteria to synthesize enzymes with keratinolytic activity and to study some of the physicochemical properties of the most active enzyme preparation. The object of the study was 10 strains of actinobacteria isolated from bottom sediments in the area of the Pradneprovsky trench of the Black Sea shelf. Methods. Caseinolytic (general proteolytic) activity was determined by the Anson method modified by Petrova, based on the quantitative determination of tyrosine, which is formed during the enzymatic hydrolysis of casein. Keratinase activity was determined by UV absorption at 280 nm of the hydrolysis products of keratin-containing raw materials. The cultivation of actinobacteria was carried out in a liquid nutrient medium with the addition of defatted chicken feathers as the main source of carbon and nitrogen. Results. The ability to hydrolyze keratin was found in five cultures. Moreover, all the strains studied were practically unable to break down casein. The Acty 9 strain (12 U/ml) showed the highest keratinase activity. Additional introduction of NaCl to the nutrient medium did not have a positive effect on the enzymes synthesis. The study of the physicochemical properties of the enzyme preparation Acty 9 showed that the pH and thermooptimum were 9.0 and 60°C, respectively. It retained 100% of the initial activity in the range of pH 7.0–10.0 after 3 h and 95% activity at pH 8.0 after 24 h of incubation. The studied enzyme preparation was thermostable, since it remained active for 3 h at 50°C and 1 h at 60°C. Conclusions. The extracellular keratinase synthesized by actinobacterium Acty 9 is promising for further research, since the enzyme is pH and thermostable and is not inferior in its physicochemical properties to those previously described in the literature.

APA, Harvard, Vancouver, ISO, and other styles

24

Rozi, Anhar, Ikhsanul Khairi, Reni Tri Cahyani, Stephani Bija, Nurhikma Nurhikma, Nuring Wulansari, Deden Yusman Maulid, Siluh Putu Sri Dia Utari, Diah Anggraini Wulandari, and Tati Nurhayati. "AKTIVITAS ENZIM KATEPSIN PADA IKAN LELE (Clarias sp.) PADA PERLAKUAN SUHU DAN SUBSTRAT YANG BERBEDA." JURNAL PERIKANAN TROPIS 7, no. 2 (December 5, 2020): 211. http://dx.doi.org/10.35308/jpt.v7i2.2390.

Full text

Abstract:

Cathepsin was proteolytic enzyme which is found animal tissues included fish. Cathepsin found in fish muscle tissue, cathepsin and other hydrolyzing enzymes were place in subcellular organelles and divided into two places, that was in muscle fibers and extracellular matrix. The aimed of this study was to the characterization of cathepsin enzyme especially catfish. So that in enviromental condition that can increased the activity of cathepsin enzyme an approtiate handling process can be carried out. The method of analyze enzyme activity, while the measurement of protein concentration refered to Bradford (1976). The treatments in this study was determination temperature (30oC, 40oC, 50oC, dan 60oC) and substrate (1.5% 2%, 2.5%). The result showed of enzyme activity with detrmination temperature very influential and fluctuating, the optimum temperature was 30oC where the activity reaches 0.38 U/ml. The best activity treatment of substrate was 1.5% where the activity reaches 0.42 U/ml. BSA Standard curve with regression equation y = 0.95x + 0.109.Keywords: Cathepsin, enzyme, substrate, temperature

APA, Harvard, Vancouver, ISO, and other styles

25

Ferreira, Renato Rodrigues, Ariane Vendemiatti, Priscila Lupino Gratão, Peter John Lea, and Ricardo Antunes Azevedo. "Determination of aspartate kinase activity in maize tissues." Scientia Agricola 62, no. 2 (April 2005): 184–89. http://dx.doi.org/10.1590/s0103-90162005000200015.

Full text

Abstract:

Lysine, threonine, methionine and isoleucine are synthesized from aspartate in a branched pathway in higher plants. Aspartate kinase plays a key role in the control of the aspartate pathway. The enzyme is very sensitive to manipulation and storage and the hydroxamate assay normally used to determine aspartate kinase activity has to be altered according to the plant species and tissue to be analyzed. We have optimized the assay for the determination of aspartate kinase in maize plants callus cell cultures. Among all the assay parameters tested, the concentration of ATP/Mg and temperature were critical for enzyme activity. In the case of temperature, 35°C was shown to be the optimum temperature for aspartate kinase activity.

APA, Harvard, Vancouver, ISO, and other styles

26

Hansen, O., and T. Clausen. "Quantitative determination of Na+-K+-ATPase and other sarcolemmal components in muscle cells." American Journal of Physiology-Cell Physiology 254, no. 1 (January 1, 1988): C1—C7. http://dx.doi.org/10.1152/ajpcell.1988.254.1.c1.

Full text

Abstract:

A recurring problem in the characterization of plasma membrane enzymes in tissues and cells is whether the samples tested are representative for the entire population of enzyme molecules present in the starting material. Measurements of [3H]-ouabain binding, enzyme activity, and maximum transport capacity all indicate that the concentration of Na+-K+ pumps in mammalian skeletal muscle is high (300-800 pmol/g wet wt). Studies on Na+-K+-ATPase activity in isolated sarcolemma, however, generally give little or no information on total cellular enzyme concentration. Due to the low and variable enzyme recovery (0.2-8.9%), such subcellular preparations may, therefore, give misleading data on factors regulating Na+-K+-ATPase in heart and skeletal muscle cells. As the same isolation and purification procedures are used for the study of other sarcolemmal components (lipids, hormone receptors, enzymes, and other transport systems), this inadequate recovery has general implications for statements on regulatory changes in the sarcolemmal composition of muscle cells. On the other hand, complete quantification of Na+-K+-ATPase in muscle tissue can now be achieved using simple procedures and the entire material (intact muscle fibers, biopsies, and whole homogenates). Recent studies have shown that regulatory changes in the entire population of Na+-K+ pumps in muscle can be quantified in measurements of [3H]-ouabain binding, K+-activated 3-O-methylfluorescein phosphatase activity, as well as maximum ouabain suppressible Na+-K+ transport capacity.

APA, Harvard, Vancouver, ISO, and other styles

27

Saruta, H., Y. Ashihara, M. Sugiyama, M. Roth, E. Miyagawa, Y. Kido, and Y. Kasahara. "Colorimetric determination of carboxypeptidase A activity in serum." Clinical Chemistry 32, no. 5 (May 1, 1986): 748–51. http://dx.doi.org/10.1093/clinchem/32.5.748.

Full text

Abstract:

Abstract This simple, reproducible colorimetric method for determining the activity of carboxypeptidase A (EC 3.4.17.1) is based on measuring the absorbance at 505 nm of a quinoneimine dye produced from the action of this enzyme on the new substrate p-hydroxybenzoyl-glycyl-L-phenylalanine. The enzyme acts on the substrate to produce p-hydroxybenzoyl-glycine and L-phenylalanine. The former is then hydrolyzed by hippuricase (EC 3.5.1.14) to produce p-hydroxybenzoic acid and glycine. Finally, oxidative coupling of p-hydroxybenzoic acid with 4-aminoantipyrine by sodium periodate forms a quinoneimine dye. The Km for the reaction with this substrate is 3.6 mmol/L; the optimum pH is 7.8. Our within-run and between-run CVs are 4.3% and 6.6%, respectively. The activity of carboxypeptidase A in serum correlates well with that of lipase (r = 0.96) and immunoreactive elastase-1 (r = 0.76).

APA, Harvard, Vancouver, ISO, and other styles

28

Khodayari, S., and F* Kafilzadeh. "Determination of Keratinase Enzyme Activity by Bacillus megatrium SKH14 Strain." Journal of Health 12, no. 3 (November 1, 2021): 340–48. http://dx.doi.org/10.52547/j.health.12.3.340.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Rossomando, Edward F. "Application of high-performance liquid chromatography to enzyme activity determination." Journal of Chromatography B: Biomedical Sciences and Applications 492 (August 1989): 361–75. http://dx.doi.org/10.1016/s0378-4347(00)84475-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

McNeil, Calum J., I. John Higgins, and Joe V. Bannistert. "Amperometric determination of alkaline phosphatase activity: application to enzyme immunoassay." Biosensors 3, no. 4 (January 1987): 199–209. http://dx.doi.org/10.1016/0265-928x(87)85001-0.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Orhan, Furkan, and Hülya Akincioglu. "Determination of carbonic anhydrase enzyme activity in halophilic/halotolerant bacteria." Applied Soil Ecology 155 (November 2020): 103650. http://dx.doi.org/10.1016/j.apsoil.2020.103650.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Cherny, V. V., V. M. Mirsky, V. S. Sokolov, and V. S. Markin. "BLM as enzyme-sensitive electrode: determination of the phospholipase activity." Journal of Electroanalytical Chemistry and Interfacial Electrochemistry 275, no. 3 (June 1989): 373–78. http://dx.doi.org/10.1016/0022-0728(89)87237-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Ritte, Gerhard, Martin Steup, Jens Kossmann, and James R. Lloyd. "Determination of the starch-phosphorylating enzyme activity in plant extracts." Planta 216, no. 5 (March 2003): 798–801. http://dx.doi.org/10.1007/s00425-002-0931-1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Cherny, V. V., V. M. Mirsky, V. S. Sokolov, and V. S. Markin. "BLM as enzyme-sensitive electrode: Determination of the phospholipase activity." Bioelectrochemistry and Bioenergetics 21, no. 3 (June 1989): 373–78. http://dx.doi.org/10.1016/0302-4598(89)85015-9.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Trojan, Václav, Ladislav Havel, Karel Stejskal, Ivo Fabrik, Jiří Baloun, Vojtěch Adam, Josef Zehnálek, and René Kizek. "Novel assay for determination of activity of enzyme phytochelatin synthase." Journal of Biotechnology 136 (October 2008): S674. http://dx.doi.org/10.1016/j.jbiotec.2008.07.1563.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Michel, Serge, Anouk Courseaux, Corinne Miquel, Jean-Michel Bernardon, Rainer Schmidt, Braham Shroot, Scott M. Thacher, and Uwe Reichert. "Determination of retinoid activity by an enzyme-linked immunosorbent assay." Analytical Biochemistry 192, no. 1 (January 1991): 232–36. http://dx.doi.org/10.1016/0003-2697(91)90213-d.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Herkner, K., R. Schaupal, and U. Goedl. "Enzyme activity determination by radio gas chromatography on capillary columns." Journal of High Resolution Chromatography 8, no. 9 (September 1985): 558–61. http://dx.doi.org/10.1002/jhrc.1240080916.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Isheanesu Dzambi and Rumbidzai Mangoyi. "The effects of Psidium guajava leaf extract on the production of cellulases and glucose oxidases by Aspergillus niger." GSC Advanced Research and Reviews 5, no. 2 (November 30, 2020): 118–22. http://dx.doi.org/10.30574/gscarr.2020.5.2.0109.

Full text

Abstract:

Aspergillus niger, is a filamentous fungus and producer of industrial enzymes such as glucose oxidases and cellulases. These enzymes are naturally produced by the fungus in order to digest and absorb nutrients from its environment. However, the enzyme quantities that are naturally produced are low. Thus, the aim of this study was to determine the effects of Psidum guajava leaf extract on the production of cellulases and glucose oxidases from Aspergillus niger. The leaves of Psidium guajava were extracted using absolute methanol. Aspergillus niger was then grown in the presence and absence of the extract in order to investigate the effects of extract on enzyme production by the fungus. The enzymes secreted into the broth medium were isolated by centrifugation. The supernatant which contained the secreted enzymes was used for the determination of enzyme activity. Enzyme activity was determined using the specific substrate for the specific enzyme, such as 2 % cellulose for cellulase and standard glucose solution for glucose oxidase. The results showed that the Psidium guajava leaf extract had an effect on production and activity of cellulases and glucose oxidases. From this study, it was noted that the Psidium guajava leaf extract may be used to induce the production of enzymes by Aspergillus niger and these enzymes may be of industrial use.

APA, Harvard, Vancouver, ISO, and other styles

39

de Groot, H., H. de Groot, and T. Noll. "Enzymic determination of inorganic phosphates, organic phosphates and phosphate-liberating enzymes by use of nucleoside phosphorylase-xanthine oxidase (dehydrogenase)-coupled reactions." Biochemical Journal 230, no. 1 (August 15, 1985): 255–60. http://dx.doi.org/10.1042/bj2300255.

Full text

Abstract:

Coupled enzyme assays are described for measuring inorganic phosphates, organic phosphates and phosphate-liberating enzymes in biological material. The assays all determine Pi by its reaction with inosine, catalysed by nucleoside phosphorylase; this yields ribose 1-phosphate and hypoxanthine. The hypoxanthine is oxidized to uric acid by xanthine oxidase, and may be measured either by the absorbance of the uric acid, or by the formazan formed when a tetrazolium salt is used as the oxidant. The coupled enzyme assays are characterized by high sensitivity, quantitative utilization of phosphates and stoichiometric formation of the measurable products, measurement at pH 6.0-8.5, determination of phosphates within a single analytical step, and continuous measurement of phosphohydrolase activity in a corresponding rate assay. Examples include determinations of substrates such as Pi, PPi and AMP, and of enzymes such as 5′-nucleotidase, inorganic pyrophosphatase and glucose-6-phosphatase. Directions for further examples are given.

APA, Harvard, Vancouver, ISO, and other styles

40

Kusumadjaja, Aline Puspita, and Rita Puspa Dewi. "DETERMINATION of OPTIMUM CONDITION of PAPAIN ENZYME FROM PAPAYA VAR JAVA (Carica papaya )." Indonesian Journal of Chemistry 5, no. 2 (June 14, 2010): 147–51. http://dx.doi.org/10.22146/ijc.21822.

Full text

Abstract:

A study to investigate the optimum condition of papain enzyme has been carried out. The condition that are investigated are pH and temperature, based on measurement of enzyme activity which is defined as mmole tyrosin that are released in reaction between papain enzyme and casein as substrat per minute. In this research, the papain enzyme was isolated from pepaya burung varietas Java. The enzyme was partially purified by precipitation method using 30% - 50% saturated acetone. The result showed that the optimum conditions of papain enzyme are in pH 6 with activity 2,606 U/mL, and temperature at 50 oC with activity 2,469 U/mL. Keywords : Papaya var Java, papain, optimum condition, enzymatic activity

APA, Harvard, Vancouver, ISO, and other styles

41

Gorski, T. P., and D. J. Campbell. "Angiotensin-converting enzyme determination in plasma during therapy with converting enzyme inhibitor: two methods compared." Clinical Chemistry 37, no. 8 (August 1, 1991): 1390–93. http://dx.doi.org/10.1093/clinchem/37.8.1390.

Full text

Abstract:

Abstract For normal and above-normal concentrations of angiotensin-converting enzyme (ACE; EC 3.4.15.1) activity in plasma, results of a manual fluorometric method [with hippuryl-histidyl-leucine (HHL), 5 mmol/L, as substrate] correlated well with those of an automated spectrophotometric method [with 3-(2-furylacryloyl)-L-phenylalanyl-glycyl-glycine (FAPGG), 2 mmol/L, as substrate]. However, for patients receiving converting enzyme inhibitor (CEI) therapy, the spectrophotometric method showed much greater suppression of plasma ACE activity than did the fluorometric method. To determine which of the two methods provided a more reliable indication of ACE inhibition in vivo, we measured plasma ACE, angiotensin I (ANG I), and angiotensin II (ANG II) in patients receiving the CEI perindopril. During perindopril therapy, changes in the ratio of ANG II:ANG I, an index of ACE activity in vivo, showed a close agreement with changes in plasma ACE activity measured with FAPGG as substrate, but not with HHL as substrate. We conclude that measurement of ACE activity in vitro with FAPGG as substrate provides a reliable measure of changes in conversion of ANG I to ANG II in vivo during CEI therapy.

APA, Harvard, Vancouver, ISO, and other styles

42

GIROTTI, STEFANO, SANDRO LODI, ELIDA FERRI, GRAZIELLA LASI, FABIANA FINI, SEVERINO GHINI, and ROLANDO BUDINI. "Chemiluminescent determination of xanthine oxidase activity in milk." Journal of Dairy Research 66, no. 3 (August 1999): 441–48. http://dx.doi.org/10.1017/s002202999900360x.

Full text

Abstract:

A chemiluminescent method for determining xanthine oxidase (XOD) activity was developed and applied to the assay of milk enzyme activity using a photomultiplier luminometer. Various kinds of milk and cream samples were analysed for XOD content. In pasteurized milk, XOD activity depended on the fat content and in UHT milk it disappeared owing to the heat treatment. Milk sample preparation was very simple, requiring only homogenization at 40°C followed by a 1[ratio ]10 dilution with UHT (‘XOD-free’) milk. The assay was carried out at 25°C. The response obtained from XOD standard solutions in milk was linear from 0·1 to 500 enzyme units (U) l−1, but for the actual milk samples values ranged only from 1 to 135 U l−1. The detection limit at 2 SD was 0·1 U l−1 in milk, while in buffer it was 100 times lower. The intra-assay and interassay CV for XOD activity in milk were 6–12%.

APA, Harvard, Vancouver, ISO, and other styles

43

Shanthi, Rangasamy. "Hemocytes Lysate Supernatant Derived Phenoloxidase Activity in the Hemolymph of Giant Freshwater Prawn Macrobrachium rosenbergii (De Man, 1879)." International Journal of Zoology and Animal Biology 5, no. 5 (2022): 1–13. http://dx.doi.org/10.23880/izab-16000403.

Full text

Abstract:

The aim of the present study attempted to find the cellular immune response in Macrobrachium rosenbergii by melanization reaction produced by hemocytes lysate supernatant (HLS) phenoloxidase (PO) activity. The substrate affinity of the PO enzyme was determined using different phenolic substrates and it was found that the diphenols and polyphenol were oxidized. Hence, the enzyme was characterized as a catechol oxidase type of PO and 3,4-dihydroxy-DL-phenylalanine (DL-DOPA) showed the highest substrate affinity to the HLS. The optimal enzyme activity was observed at 5 mM DL-DOPA in 10 mM Tris-HCl buffer at a pH of 7.5 at 25° C for 20 min and absorbance at 490 nm. Kinetic characteristics of HLS from the prawn were determined. Determination of optimal conditions of PO activity in the HLS has also been attempted. These results depicted that in the presence of PO and peroxidase inhibitors, phenylthiourea (PTU) and tropolone respectively have a decreased HLS PO activity. The determination of PO activity was also highly activated by trypsin, sodium dodecyl sulphate (6 mg.ml-1) and laminarin (4 mg.ml-1) enzyme expression. We also identified the chemicals causing in vitro inhibition or activation of the enzyme as an HLS of the freshwater prawn having a potent PO activity.

APA, Harvard, Vancouver, ISO, and other styles

44

Klein, Allan E., John Freiberg, Steven Same, and Maryanne Carroll. "Rapid Colorimetric Determination of Activity of Subtilisin Enzymes in Cleaning Products." Journal of AOAC INTERNATIONAL 72, no. 6 (November 1, 1989): 881–82. http://dx.doi.org/10.1093/jaoac/72.6.881.

Full text

Abstract:

Abstract A new colorimetric method is described for the determination of enzymatic activity of subtilisin in cleaning products. The procedure is more rapid and precise than the casein digestion methods commonly used to assay protease activity. The principle of the colorimetric method depends on the determination rate of p-nitrophenol released on hydrolysis of N-CBZ-L-leucine-/Miitrophenyl ester at pH 8.0 by subtilisin, with correction for any nonenzymatic (spontaneous) hydrolysis of the substrate. Because of the broad range of hydrolytic activity of this enzyme, and the difficulties in predicting its proteolytic activity, this hydrolytic rate was chosen as a general indicator of subtilisin enzyme behavior. The slope for 7 replicate standard curves generated over a 6 week period exhibited a relative standard deviation of 7.5%, and 8.0% for 20 replicates with an enzyme cleaning product. Papain does not interfere with this assay.

APA, Harvard, Vancouver, ISO, and other styles

45

Mass, Mijal, Lionel S. Veiga, Octavio Garate, Gloria Longinotti, Ana Moya, Eloi Ramón, Rosa Villa, Gabriel Ybarra, and Gemma Gabriel. "Fully Inkjet-Printed Biosensors Fabricated with a Highly Stable Ink Based on Carbon Nanotubes and Enzyme-Functionalized Nanoparticles." Nanomaterials 11, no. 7 (June 23, 2021): 1645. http://dx.doi.org/10.3390/nano11071645.

Full text

Abstract:

Enzyme inks can be inkjet printed to fabricate enzymatic biosensors. However, inks containing enzymes present a low shelf life because enzymes in suspension rapidly lose their catalytic activity. Other major problems of printing these inks are the non-specific adsorption of enzymes onto the chamber walls and stability loss during printing as a result of thermal and/or mechanical stress. It is well known that the catalytic activity can be preserved for significantly longer periods of time and to harsher operational conditions when enzymes are immobilized onto adequate surfaces. Therefore, in this work, horseradish peroxidase was covalently immobilized onto silica nanoparticles. Then, the nanoparticles were mixed into an aqueous ink containing single walled carbon nanotubes. Electrodes printed with this specially formulated ink were characterized, and enzyme electrodes were printed. To test the performance of the enzyme electrodes, a complete amperometric hydrogen peroxide biosensor was fabricated by inkjet printing. The electrochemical response of the printed electrodes was evaluated by cyclic voltammetry in solutions containing redox species, such as hexacyanoferrate (III/II) ions or hydroquinone. The response of the enzyme electrodes was studied for the amperometric determination of hydrogen peroxide. Three months after the ink preparation, the printed enzyme electrodes were found to still exhibit similar sensitivity, demonstrating that catalytic activity is preserved in the proposed ink. Thus, enzyme electrodes can be successfully printed employing highly stable formulation using nanoparticles as carriers.

APA, Harvard, Vancouver, ISO, and other styles

46

Daniel, Roy M., Michelle E. Peterson, Michael J. Danson, Nicholas C. Price, Sharon M. Kelly, Colin R. Monk, Cristina S. Weinberg, Matthew L. Oudshoorn, and Charles K. Lee. "The molecular basis of the effect of temperature on enzyme activity." Biochemical Journal 425, no. 2 (December 23, 2009): 353–60. http://dx.doi.org/10.1042/bj20091254.

Full text

Abstract:

Experimental data show that the effect of temperature on enzymes cannot be adequately explained in terms of a two-state model based on increases in activity and denaturation. The Equilibrium Model provides a quantitative explanation of enzyme thermal behaviour under reaction conditions by introducing an inactive (but not denatured) intermediate in rapid equilibrium with the active form. The temperature midpoint (Teq) of the rapid equilibration between the two forms is related to the growth temperature of the organism, and the enthalpy of the equilibrium (ΔHeq) to its ability to function over various temperature ranges. In the present study, we show that the difference between the active and inactive forms is at the enzyme active site. The results reveal an apparently universal mechanism, independent of enzyme reaction or structure, based at or near the active site, by which enzymes lose activity as temperature rises, as opposed to denaturation which is global. Results show that activity losses below Teq may lead to significant errors in the determination of ΔG*cat made on the basis of the two-state (‘Classical’) model, and the measured kcat will then not be a true indication of an enzyme's catalytic power. Overall, the results provide a molecular rationale for observations that the active site tends to be more flexible than the enzyme as a whole, and that activity losses precede denaturation, and provide a general explanation in molecular terms for the effect of temperature on enzyme activity.

APA, Harvard, Vancouver, ISO, and other styles

47

Khaleeluddin, Khaja, and Linda Bradford. "Dual Enzyme Method for Determination of Total Nonstructural Carbohydrates." Journal of AOAC INTERNATIONAL 69, no. 1 (January 1, 1986): 162–66. http://dx.doi.org/10.1093/jaoac/69.1.162.

Full text

Abstract:

Abstract Total nonstructural carbohydrates (TNC) in plant tissue are underestimated by single enzyme (a-amylase or glucoamylase) extraction and overestimated by mild acid hydrolysis. A combination of glucoamylase and mycolase degraded starch completely to glucose at 60°C and pH 4.9. This dual enzyme extraction procedure was effective in determining TNC in plant tissues that do not accumulate fructosans. The reducing sugar (mainly glucose and/or fructose) extracts produced by enzymatic digestion of plant tissue were clarified with barium hydroxide and zinc sulfate solutions and analyzed by the Shaffer-Somogyi copperiodometric titration method. The dual enzyme method hydrolyzed pure starch derived from corn, wheat, and potato, and potato-soluble starch to about 100% glucose, whereas mycolase only yielded about 88% hydrolysis. Although corn starch was completely hydrolyzed in 2 h by the dual enzyme method, plant tissues required at least 24 h hydrolysis for maximum TNC values. Lead acetate precipitation of the protein in the dual enzyme extracts interfered with the copper-iodometric titration. Gelatinization of starch in plant tissue by autoclaving gave higher TNC values than heating on a hot plate for 5 min. The Schaffer-Somogyi copper iodometric titration method could be used to measure/or define the activity of certain enzymes.

APA, Harvard, Vancouver, ISO, and other styles

48

Potier, M., and S. Giroux. "Regulatory proteins (inhibitors or activators) affect estimates of Mr of enzymes and receptors by radiation inactivation. A theoretical model." Biochemical Journal 226, no. 3 (March 15, 1985): 797–801. http://dx.doi.org/10.1042/bj2260797.

Full text

Abstract:

The radiation-inactivation method allows the determination of the Mr of enzymes and receptors by monitoring the decay of biological activity as a function of absorbed dose. The presence of regulatory or effector proteins (inhibitors or activators) associated with an enzyme or receptor, or released in the preparation after tissue homogenization, may affect the decay of biological activity. How the activity is affected, however, will depend on the type of inhibition (competitive or non-competitive), the inhibitor or activator concentration, the dissociation constant of the enzyme-effector system, and the effector Mr relative to that of the enzyme. Since little is known on how effector proteins influence radiation inactivation of enzymes and receptors, we have considered a theoretical model in an effort to provide a framework for the interpretation of experimentally obtained data. Our model predicts that competitive and non-competitive inhibitors of enzymes could be distinguished by analysing irradiated samples with various substrate concentrations. Inhibitors will decrease whereas activators will increase the apparent target size of enzymes or receptors.

APA, Harvard, Vancouver, ISO, and other styles

49

Perperopoulou, Fereniki, Maria Fragoulaki, Anastassios C. Papageorgiou, and Nikolaos E. Labrou. "Directed Evolution of a Glutathione Transferase for the Development of a Biosensor for Alachlor Determination." Symmetry 13, no. 3 (March 12, 2021): 461. http://dx.doi.org/10.3390/sym13030461.

Full text

Abstract:

In the present work, DNA recombination of three homologous tau class glutathione transferases (GSTUs) allowed the creation of a library of tau class GmGSTUs. The library was activity screened for the identification of glutathione transferase (GST) variants with enhanced catalytic activity towards the herbicide alachlor (2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide). One enzyme variant (GmGSTsf) with improved catalytic activity and binding affinity for alachlor was identified and explored for the development of an optical biosensor for alachlor determination. Kinetics analysis and molecular modeling studies revealed a key mutation (Ile69Val) at the subunit interface (helix α3) that appeared to be responsible for the altered catalytic properties. The enzyme was immobilized directly on polyvinylidenefluoride membrane by crosslinking with glutaraldehyde and was placed on the inner surface of a plastic cuvette. The rate of pH changes observed as a result of the enzyme reaction was followed optometrically using a pH indicator. A calibration curve indicated that the linear concentration range for alachlor was 30–300 μM. The approach used in the present study can provide tools for the generation of novel enzymes for eco-efficient and environment-friendly analytical technologies. In addition, the outcome of this study gives an example for harnessing protein symmetry for enzyme design.

APA, Harvard, Vancouver, ISO, and other styles

50

Martin, T. P., A. C. Vailas, J. B. Durivage, V. R. Edgerton, and K. R. Castleman. "Quantitative histochemical determination of muscle enzymes: biochemical verification." Journal of Histochemistry & Cytochemistry 33, no. 10 (October 1985): 1053–59. http://dx.doi.org/10.1177/33.10.4045183.

Full text

Abstract:

We established quantitative histochemical assays for the enzymatic activity of succinate dehydrogenase and alpha-glycerol phosphate dehydrogenase for cat skeletal muscle. A computer-enhanced image analysis system was used to quantitate the histochemical enzyme-activity reaction products. We describe a series of experiments that verify the reliability and validity of the assays. Histochemically determined enzyme activities were linear with respect to tissue thickness and reaction time. Biochemically determined enzyme activities were also linear with respect to tissue thickness and incubation time. Consecutive tissue sections, assayed either histochemically or biochemically, were used to establish a linear regression equation that allowed quantitative histochemically determined reaction rates, measured in optical density per minute, to be calibrated as nanomoles per minute.

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!