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Letteratura scientifica selezionata sul tema "Macromolecular defects"

Autore: Grafiati

Pubblicato: 5 ottobre 2024

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Articoli di riviste sul tema "Macromolecular defects"

McPherson, Alexander, e Yurii G. Kuznetsov. "Mechanisms, kinetics, impurities and defects: consequences in macromolecular crystallization". Acta Crystallographica Section F Structural Biology Communications 70, n. 4 (29 marzo 2014): 384–403. http://dx.doi.org/10.1107/s2053230x14004816.

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The nucleation and growth of protein, nucleic acid and virus crystals from solution are functions of underlying kinetic and thermodynamic parameters that govern the process, and these are all supersaturation-dependent. While the mechanisms of macromolecular crystal growth are essentially the same as for conventional crystals, the underlying parameters are vastly different, in some cases orders of magnitude lower, and this produces very different crystallization processes. Numerous physical features of macromolecular crystals are of serious interest to X-ray diffractionists; the resolution limit and mosaicity, for example, reflect the degree of molecular and lattice order. The defect structure of crystals has an impact on their response to flash-cooling, and terminal crystal size is dependent on impurity absorption and incorporation. The variety and extent of these issues are further unique to crystals of biological macromolecules. All of these features are amenable to study using atomic force microscopy, which provides direct images at the nanoscale level. Some of those images are presented here.

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Paganini, Chiara, Chiara Gramegna Tota, Andrea Superti-Furga e Antonio Rossi. "Skeletal Dysplasias Caused by Sulfation Defects". International Journal of Molecular Sciences 21, n. 8 (14 aprile 2020): 2710. http://dx.doi.org/10.3390/ijms21082710.

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Proteoglycans (PGs) are macromolecules present on the cell surface and in the extracellular matrix that confer specific mechanical, biochemical, and physical properties to tissues. Sulfate groups present on glycosaminoglycans, linear polysaccharide chains attached to PG core proteins, are fundamental for correct PG functions. Indeed, through the negative charge of sulfate groups, PGs interact with extracellular matrix molecules and bind growth factors regulating tissue structure and cell behavior. The maintenance of correct sulfate metabolism is important in tissue development and function, particularly in cartilage where PGs are fundamental and abundant components of the extracellular matrix. In chondrocytes, the main sulfate source is the extracellular space, then sulfate is taken up and activated in the cytosol to the universal sulfate donor to be used in sulfotransferase reactions. Alteration in each step of sulfate metabolism can affect macromolecular sulfation, leading to the onset of diseases that affect mainly cartilage and bone. This review presents a panoramic view of skeletal dysplasias caused by mutations in genes encoding for transporters or enzymes involved in macromolecular sulfation. Future research in this field will contribute to the understanding of the disease pathogenesis, allowing the development of targeted therapies aimed at alleviating, preventing, or modifying the disease progression.

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Ciesielski, Peter N., Ryan Wagner, Vivek S. Bharadwaj, Jason Killgore, Ashutosh Mittal, Gregg T. Beckham, Stephen R. Decker, Michael E. Himmel e Michael F. Crowley. "Nanomechanics of cellulose deformation reveal molecular defects that facilitate natural deconstruction". Proceedings of the National Academy of Sciences 116, n. 20 (29 aprile 2019): 9825–30. http://dx.doi.org/10.1073/pnas.1900161116.

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Technologies surrounding utilization of cellulosic materials have been integral to human society for millennia. In many materials, controlled introduction of defects provides a means to tailor properties, introduce reactivity, and modulate functionality for various applications. The importance of defects in defining the behavior of cellulose is becoming increasingly recognized. However, fully exploiting defects in cellulose to benefit biobased materials and conversion applications will require an improved understanding of the mechanisms of defect induction and corresponding molecular-level consequences. We have identified a fundamental relationship between the macromolecular structure and mechanical behavior of cellulose nanofibrils whereby molecular defects may be induced when the fibrils are subjected to bending stress exceeding a certain threshold. By nanomanipulation, imaging, and molecular modeling, we demonstrate that cellulose nanofibrils tend to form kink defects in response to bending stress, and that these macromolecular features are often accompanied by breakages in the glucan chains. Direct observation of deformed cellulose fibrils following partial enzymatic digestion reveals that processive cellulases exploit these defects as initiation sites for hydrolysis. Collectively, our findings provide a refined understanding of the interplay between the structure, mechanics, and reactivity of cellulose assemblies.

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Dauter, Zbigniew, e Mariusz Jaskólski. "Crystal pathologies in macromolecular crystallography". Postępy Biochemii 62, n. 3 (15 novembre 2016): 401–7. http://dx.doi.org/10.18388/pb.2016_45.

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Macromolecules, such as proteins or nucleic acids, form crystals with a large volume fraction of water, ~50% on average. Apart from typical physical defects and rather trivial poor quality problems, macromolecular crystals, as essentially any crystals, can also suffer from several kinds of pathologies, in which everything seems to be perfect, except that from the structural point of view the interpretation may be very difficult, sometimes even im-possible. A frequent nuisance is pseudosymmetry, or non-crystallographic symmetry (NCS), which is particularly nasty when it has translational character. Lattice-translocation defects, also called order-disorder twinning (OD-twinning), occur when molecules are packed regularly in layers but the layers are stacked (without rotation) in two (or more) discrete modes, with a unique translocation vector. Crystal twinning arises when twin domains have different orientations, incompatible with the symmetry of the crystal structure. There are also crystals in which the periodic (lattice) order is broken or absent altogether. When the strict short-range translational order from one unit cell to the next is lost but the long-range order is restored by a periodic modulation, we have a modulated crystal structure. In quasicrystals (not observed for macromolecules yet), the periodic order (in 3D space) is lost completely and the diffraction pattern (which is still discrete) cannot be even indexed using three hkl indices. In addition, there are other physical defects and phenomena (such as high mosaicity, diffraction anisotropy, diffuse scattering, etc.) which make diffraction data processing and structure solution difficult or even impossible.

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Zhang, Liangfang, e Steve Granick. "Dynamical Heterogeneity in Supported Lipid Bilayers". MRS Bulletin 31, n. 7 (luglio 2006): 527–31. http://dx.doi.org/10.1557/mrs2006.137.

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Planar-supported phospholipid bilayers are responsive surfaces that reconstruct when macromolecules adsorb. This review outlines the phenomenon of lipid diffusion “slaved” to or significantly controlled by that of macromolecular adsorbates. To elucidate such systems, we discuss the value of spatially resolved experiments at the few-molecule level, lipid diffusion compared in outer and inner leaflets of the supported bilayer, and a simple method to minimize defects by the strategy of “electrostatic stitching.”

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Li, Xiaoshi, Yiwen Ju, Quanlin Hou, Zhuo Li e Junjia Fan. "FTIR and Raman Spectral Research on Metamorphism and Deformation of Coal". Journal of Geological Research 2012 (10 luglio 2012): 1–8. http://dx.doi.org/10.1155/2012/590857.

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Under different metamorphic environments, coal will form different types of tectonically deformed coal (TDC) by tectonic stress and even the macromolecular structure can be changed. The structure and composition evolution of TDC have been investigated in details using Fourier transform infrared spectroscopy and Raman spectroscopy. The ductile deformation can generate strain energy via increase of dislocation in molecular structure of TDC, and it can exert an obvious influence on degradation and polycondensation. The brittle deformation can generate frictional heat energy and promote the metamorphism and degradation, but less effect on polycondensation. Furthermore, degradation affects the structural evolution of coal in lower metamorphic stage primarily, whereas polycondensation is the most important controlling factor in higher metamorphic stage. Tectonic deformation can produce secondary structural defects in macromolecular structure of TDC. Under the control of metamorphism and deformation, the small molecules which break and fall off from the macromolecular structure of TDC are replenished and embedded into the secondary structural defects preferentially and form aromatic rings by polycondensation. These processes improved the stability of macromolecular structure greatly. It is easier for ductile deformation to induce secondary structural defects than in brittle deformation.

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Cao, Yi, Min Liu, Kunchi Zhang, Jingjin Dong, Guangyue Zu, Yang Chen, Tingting Zhang, Dangsheng Xiong e Renjun Pei. "Preparation of linear poly(glycerol) as a T1 contrast agent for tumor-targeted magnetic resonance imaging". Journal of Materials Chemistry B 4, n. 41 (2016): 6716–25. http://dx.doi.org/10.1039/c6tb01514j.

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Song, Yu, Bo Jiang e Meijun Qu. "Macromolecular evolution and structural defects in tectonically deformed coals". Fuel 236 (gennaio 2019): 1432–45. http://dx.doi.org/10.1016/j.fuel.2018.09.080.

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Wang, Anmin, Daiyong Cao, Yingchun Wei e Zhifei Liu. "Macromolecular Structure Controlling Micro Mechanical Properties of Vitrinite and Inertinite in Tectonically Deformed Coals—A Case Study in Fengfeng Coal Mine of Taihangshan Fault Zone (North China)". Energies 13, n. 24 (15 dicembre 2020): 6618. http://dx.doi.org/10.3390/en13246618.

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In order to study the evolution of the mechanical properties and macromolecular structures in different macerals of tectonically deformed coal (TDC), vitrinite and inertinite samples were handpicked from six block TDCs in the same coal seam with an increasing deformation degree (unaltered, cataclastic, porphyroclast, scaly and powdery coal). The micro mechanical properties were tested by the nanoindentation experiment and the macromolecular structures were measured using 13C nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). The results show that the range of hardness and elastic modulus of inertinite is 0.373–1.517 GPa and 4.339–12.158 GPa, respectively, which is significantly higher than that of vitrinite with values of 0.278–0.456 GPa and 4.857–7.810 GPa, respectively. From unaltered coal to powdery coal, the hardness of vitrinite and inertinite gradually decreases, with the difference between these macerals becomes smaller and the elastic modulus of vitrinite shows an increasing trend, while that of inertinite was more variable. Both the NMR and FITR results reveal that the macromolecular structure of inertinite has similar structural transitions as vitrinite. As the degree of deformation increases, the aliphatic side chains become shorter and the aromaticity is increasing. Macromolecular alterations caused by tectonic stress is expected to produce defects in the TDCs, therefore there should be more interspacing among the macromolecular groups for the extrusion of macromolecules caused by the indenter of the nanoindentation experiment, thereby reducing the hardness. The elastic modulus of coal is believed to be related to intermolecular forces, which are positively correlated to the dipole moment. By calculating the dipole moments of the typical aromatic molecular structures with aliphatic side chains, the detachment of the aliphatic side chains and the growth of benzene rings can both increase the dipole moment, which can promote elastic modulus. In addition, the increasing number of benzene rings can create more π-π bonds between the molecules, which can lead to an increase in the intermolecular forces, further increasing the elastic modulus.

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Sun, Zhe, Koki Ikemoto, Toshiya M. Fukunaga, Takashi Koretsune, Ryotaro Arita, Sota Sato e Hiroyuki Isobe. "Finite phenine nanotubes with periodic vacancy defects". Science 363, n. 6423 (10 gennaio 2019): 151–55. http://dx.doi.org/10.1126/science.aau5441.

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Discrete graphitic carbon compounds serve as tunable models for the properties of extended macromolecular structures such as nanotubes. Here, we report synthesis and characterization of a cylindrical C304H264molecule composed of 40 benzene (phenine) units mutually bonded at the 1, 3, and 5 positions. The concise nine-step synthesis featuring successive borylations and couplings proceeded with an average yield for each benzene-benzene bond formation of 91%. The molecular structure of the nanometer-sized cylinder with periodic vacancy defects was confirmed spectroscopically and crystallographically. The nanoporous nature of the compound further enabled inclusion of multiple fullerene guests. Computations suggest that fusing many such cylinders could produce carbon nanotubes with electronic properties modulated by the periodic vacancy defects.

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Tesi sul tema "Macromolecular defects"

Yahyaoui, Ons. "Dévelοppement d'un pοlymère de haute sensibilité intégrable dans un dοsimètre gamma sans fil interrοgeable à distance". Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMC209.

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Ce travail de recherche a étudié l'effet des nanoparticules d'or sur le comportement des polymères sous rayonnements ionisants en atmosphère inerte. L'objectif était de développer des matériaux à forte émission gazeuse intégrables dans de nouveaux dosimètres miniatures, passifs, à lecture en temps réel et à longue distance. L’idée était initiale était d’insérer des nanoparticules d’or (AuNPs) dans des matrices polymères afin de tirer avantage des électrons secondaires émis par les AuNPs et d’une potentielle action catalytique pendant la phase chimique de l’irradiation. Au-delà du développement d’un nouveau polymère, cette étude avait également pour objectif d’améliorer la compréhension de l’influence des nanoparticules en phase solide et sous atmosphère inerte. Deux types de polymères ont été étudiés : le PMAA et le PE. Des nanoparticules sphériques d'or de 2 nm de diamètre ont été synthétisées et incorporées dans les polymères. Les nanocomposites ont été irradiés et les défauts macromoléculaires et l'émission gazeuse ont été analysés. Les résultats ont montré que les nanoparticules d'or ont un effet significatif sur le comportement des polymères sous rayonnements ionisants. L'effet observé dépend du type de polymère, de la concentration en nanoparticules et de la distribution des nanoparticules dans la matrice polymère. Dans le PMAA, les nanoparticules d'or accélèrent la scission des chaînes et augmentent le rendement radiochimique de dihydrogène émis dans le polymère. Dans le PE, au-dessus d’un pourcentage molaire de 1%, les nanoparticules d'or radio-protègent le polymère en réduisant la formation de défauts macromoléculaires et l'émission d'hydrogène
In this research work, we studied the effect of gold nanoparticles on the behavior of polymers under ionizing radiation under an inert atmosphere. The initial aim was to develop highly emissive materials for new miniature, passive, real-time, and long-distance read-out dosimeters by inserting gold nanoparticles (AuNPs) in a polymer matrix. The rational behind was to use either the dose enhancement by secondary electrons emitted from AuNPs or their catalytic properties when appropriate. Beyond the development of a new material, one of the objective of this work was to study the influence of nanoparticles in the solid phase and in the absence of oxygen. Two types of polymers were studied: PMAA and PE. Gold nanoparticles with a diameter of 2 nm were synthesized and incorporated into the polymers. The nanocomposites were irradiated under gamma rays or electron beams and both macromolecular defects and gas emission were analyzed. The results showed that gold nanoparticles have a significant effect on the behavior of polymers under ionizing radiation, depending on the polymer polymer, the nanoparticles concentration, and their distribution in the polymer matrix. In PMAA, gold nanoparticles accelerate chain scission and increase the hydrogen emission radiochemical yield. In PE, beyong a molar percentage of 1%, gold nanoparticles radioprotect the polymer by reducing the formation of macromolecular defects and hydrogen emission

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(11022450), Jonathan Mark LaCombe. "DYRK1A-RELATED TRABECULAR DEFECTS IN MALE TS65DN MICE EMERGE DURING A CRITICAL DEVELOPMENTAL WINDOW". Thesis, 2021.

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Down syndrome (DS) is a complex genetic disorder caused by the triplication of human chromosome 21 (Hsa21). The presence of an extra copy of an entire chromosome greatly disrupts the copy number and expression of over 350 protein coding genes. This gene dosage imbalance has far-reaching effects on normal development and aging, leading to cognitive and skeletal defects that emerge earlier in life than the general population.

The present study begins by characterizing skeletal development in young male Ts65Dn mice to test the hypothesis that skeletal defects in male Ts65Dn mice are developmental in nature.Femurs from young mice ranging from postnatal day 12- to 42-days of age (P12-42) were measured and analyzed by microcomputed tomography (μCT). Cortical defects were present generally throughout development, but trabecular defects emerged at P30 and persisted until P42.

The gene Dual-specificity tyrosine-regulated kinase 1a (Dyrk1a) is triplicated in both DS and in Ts65Dn mice and has been implicated as a putative cause of both cognitive and skeletal defects. To test the hypothesis that trisomic Dyrk1a is related to the emergence of trabecular defects at P30, expression of Dyrk1a in the femurs of male Ts65Dn mice was quantified by qPCR. Expression was shown to fluctuate throughout development and overexpression generally aligned with the emergence of trabecular defects at P30.

The growth rate in trabecular measures between male Ts65Dn and euploid littermates was similar between P30 and P42, suggesting a closer look into cellular mechanisms at P42. Assessment of proliferation of BMSCs, differentiation and activity of osteoblasts showed no significant differences between Ts65Dn and euploid cellular activity, suggesting that the cellular microenvironment has a greater influence on cellular activity than genetic background.

These data led to the hypothesis that reduction of Dyrk1a gene expression and pharmacological inhibition of DYRK1A could be executed during a critical period to prevent the emergence of trabecular defects at P30. To tests this hypothesis, doxycycline-induced cre-lox recombination to reduce Dyrk1a gene copy number or the DYRK1A inhibitor CX-4945 began at P21. The results of both genetic and pharmacological interventions suggest that trisomic Dyrk1a does not influence the emergence of trabecular defects up to P30. Instead, data suggest that the critical window for the rescue of trabecular defects lies between P30 and P42.

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Capitoli di libri sul tema "Macromolecular defects"

Wunderlich, Bernhard, Bobby G. Sumpter, Donald W. Noid e Guanghe L. Liang. "Computer Simulation of Macromolecular Crystals and Their Defects". In Ordering in Macromolecular Systems, 35–49. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-78893-2_3.

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Sackmann, E., A. Fischer e W. Frey. "Polymorphism of Monolayers of Monomeric and Macromolecular Lipids: On the Defect Structure of Crystalline Phases and the Possibility of Hexatic Order Formation". In Springer Proceedings in Physics, 25–37. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-642-83202-4_5.

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Vekilov, Peter G. "Molecular Mechanisms of Defect Formation". In Macromolecular Crystallography, Part C, 170–88. Elsevier, 2003. http://dx.doi.org/10.1016/s0076-6879(03)68010-9.

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Wang, Jingyi, Hui Xiao e Huaxin Wang. "Modification Strategies of Titanium Dioxide". In Updates on Titanium Dioxide [Working Title]. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.111636.

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Titanium dioxide (TiO2) is a standard white pigment. However, when TiO2 is exposed to ultraviolet light, it will catalyze the degradation of the surrounding organic matrix. Surface coating of TiO2 is an effective method for reducing the catalytic effect of TiO2. It can also improve the dispersion of TiO2 in an organic matrix. This review critically introduces recent results on the surface coating of TiO2. First, the main features of TiO2, including processes, structure, and final properties, are described briefly. Second, this chapter reports and discusses different surface coating methods for TiO2 with inorganic oxides and organic matter. Inorganic oxides, such as Al2O3, SiO2, and ZrO2, would form a continuous dense film and block the defects of the TiO2 lattice. They can give TiO2 excellent weather resistance. The organic matter available for surface treatment includes the surfactant, the coupling agent, and the macromolecule. They can improve the affinity of TiO2 with various organic matrices. Surfactant treatment is relatively simple. Coupling agents can give TiO2 more novel properties, such as thermal stability. Macromolecules can increase the volume of TiO2 particles through steric hindrance and improve the dispersion of TiO2 in an organic matrix. However, coating TiO2 in a single matter is challenging to meet the increasing performance requirements. Therefore, it is necessary to study further the effect of co-coating with different inorganic oxides and organic matter on the structure and properties of TiO2.

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Dhamija, Radhika, Erin Conboy e Lily C. Wong-Kisiel. "Lysosomal Storage Disorders". In Mayo Clinic Neurology Board Review, a cura di Kelly D. Flemming, 1106–13. Oxford University Press, 2021. http://dx.doi.org/10.1093/med/9780197512166.003.0121.

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Lysosomes are membrane-bound organelles that degrade various macromolecules. Lysosomal storage diseases are a clinically, enzymatically, and genetically heterogeneous group of disorders resulting from intracellular accumulation of substrates. Mechanisms of lysosomal storage disorders include 1) primary deficiency of specific hydrolases; 2) defects in activator proteins required for enzyme-substrate interactions in posttranslational modification of enzymes or in transport of the substrate from lysosomes; and 3) abnormalities of fusion between autophagic vacuoles and lysosomes. Substrate accumulation is slowly progressive, leading to considerable morbidity and mortality.

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Lachmann, Robin H. "Disorders of Carbohydrate Metabolism". In Oxford Textbook of Endocrinology and Diabetes 3e, a cura di John A. H. Wass, Wiebke Arlt e Robert K. Semple, 1893–901. Oxford University Press, 2021. http://dx.doi.org/10.1093/med/9780198870197.003.0234.

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Sugar molecules play many roles in metabolism. Glucose is an essential source of energy in the body, but carbohydrates also have important structural and signalling functions as constituents of glycoproteins, glycolipids, and glycosaminoglycans. Disorders of carbohydrate metabolism, although caused be defects in individual enzymes, are best viewed as disorders of metabolic pathways. Their tissue pathology can be due to deficiency of a product of metabolism, but just as often it is due to accumulation of toxic molecules which cannot be metabolized. In this chapter, a number of monogenic diseases will be described which involve the monosaccharides glucose, galactose, and fructose, and their roles in intermediary metabolism. The many other inherited metabolic diseases which affect the formation of glycosylated macromolecules (the congenital disorders of glycosylation) or their breakdown (lysosomal storage disorders) will not be discussed.

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Deegan, Patrick B., e Timothy M. Cox. "Lysosomal disease". In Oxford Textbook of Medicine, a cura di Timothy M. Cox, 2121–56. Oxford University Press, 2020. http://dx.doi.org/10.1093/med/9780198746690.003.0235.

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The lysosome is a ubiquitous, single membrane-bond intracellular organelle which continuously recycles biological macromolecules: it not only breaks down cell components but has a dynamic role in nutrient and energy sensing that, through regulatory signalling, is critical for homeostasis and metabolic economy of the cell. More than 80 lysosomal diseases caused by single gene defects are known. Biochemical classification identifies (1) sphingolipidoses; (2) mucopolysaccharidoses; (3) glycoproteinoses; (4) glycogenosis, with or without lysosomal debris derived from subcellular organelles due to impaired autophagy; and (5) miscellaneous conditions with multiple classes of storage material such as the neuronal ceroid lipofuscinoses. Functional classification describes deficiency of (1) a specific acid hydrolase activity, (2) an activator protein, (3) a lysosomal membrane protein or transporter, or (4) abnormal post-translational modification of lysosomal proteins, and (5) abnormal biogenesis of lysosomes. A unified classification will emerge from genetic characterization integrated with clinicopathological manifestations of the individual disorders. Fabry’s and Gaucher’s diseases (glycosphingolipidoses) are probably the most frequent in the general population, but certain lysosomal diseases are over-represented in particular groups where consanguinity or endogamy is high. Other diseases discussed in this chapter include (1) cystinosis, (2) the mucopolysaccharidoses, (3) Pompe’s disease (glycogen storage disease type II), (4) Niemann–Pick diseases, (5) lysosomal acid lipase deficiency, (6) Danon’s disease, and (7) diseases more recently attributed to primary defects in lysosomes and related organelles.

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Glusker, Jenny P., e Aldo Domenicano. "X-ray crystallography: an introduction". In Accurate Molecular Structures, 126–69. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780198555568.003.0006.

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Abstract The chemist would like to be able to visualize molecules and the atoms in them and so obtain a direct three-dimensional view. For example, when considering reaction mechanisms it is difficult to determine the extent of steric hindrance or the accessibility of functional groups if one does not have a three-dimensional view of the system. The electron microscope can, as was shown, for example, by Labaw and Wyckoff (1958), be used to view macromolecules such as those of viruses. It can also be used to image the lattice defects in certain stable inorganic compounds (Iijima 1973). But when one needs precise geometrical data on molecules, an excellent method to choose is an analysis of the X-ray or neutron diffraction patterns obtained from single crystals of the substance of interest. The result of such an analysis is a vast wealth of data on the relative positions of atoms, ions or molecules in a crystal, and a measure of the variability of these positions.

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Atti di convegni sul tema "Macromolecular defects"

Spitzer, S. G., P. Usharani, A. D. Roser, C. K. Kasper e S. G. Bajaj. "THE CATALYTIC TRIAD RESIDUES (HIS221, ASP269, SER365) AND THE BINDING POCKET RESIDUE (ASP359) IN FACTOR IXBm ELSINORE (IXBmLE) ARE NOT ALTERED". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644071.

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Previous studies suggested that the defect in IXBmLE (a nonfunctional variant of human IX) is either in the catalytic triad or at the site(s) of interaction with the macromolecular substrates (antithrombin III, factor VII or factor X). To distinguish between these possibilities, we isolated a complete IX cDNA clone from a human liver cDNA library. We also constructed a genomic library (in phage EMBL3) using DNA of the BmLE patient. The library was screened with normal IX cDNA and with synthetic oligonucleotides. The positive clones containing the exons coding for IX were plaque purified. Two clones which contained the coding sequence of the catalytic domain, i.e., His221 (exon VII), and Asp269, Asp359, and Ser365 (exon VIII) were selected for further studies. The phage containing exon VIII was first digested with Sail and EcoRI and a 2-Kb fragment, which hybridized with the segment of cDNA containing exon VIII, was gel purified. The 2-Kb fragment was further digested and the subfragments were cloned into M13; the length and direction of the fragments used in sequencing are shown below:The phage containing exon VII was digested with PstI and SalI, and a 1-Kb fragment that hybridized with the 19-mer His221 probe was subcloned into M13 phage for sequencing. The sequence starting with residue Vall96 through residue Arg403 was found to be normal. Thus, none of the residues in the catalytic domain of IXBmLE are different from that of normal IX. These data provide strong indirect evidence that the noncatalytic aminoterminal portion of IX plays a significant role in the structural recognition of the macromolecular substrates. The sequence of this region of IXBmLE should provide information about the putative residue(s) essential for this recognition.

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Rapporti di organizzazioni sul tema "Macromolecular defects"

Wunderlich, B., B. G. Sumpter, D. W. Noid e G. L. Liang. Computer simulation of macromolecular crystals and their defects. Office of Scientific and Technical Information (OSTI), giugno 1993. http://dx.doi.org/10.2172/10169093.

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