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CH19 02/06/2013 11:39:14 Page 583 19 Large-Scale Structural Characterization of Biopolymer Systems by Small-Angle Neutron Scattering Ferenc Horkay 19.1 Introduction Biopolymers are polymer structures produced by living organisms. These mole- cules, like synthetic polymers, are built from monomers. There are three main classes of biopolymers based on the chemical nature of the monomeric units and the structure of the biopolymer formed. Polypeptides are chains of amino acids linked together by peptide bonds. Proteins consist of one or more polypeptide chains folded into a globular or brous form in a biologically functional way. Many proteins have structural or mechanical functions, such as actin in the muscle and various proteins in the cytoskeleton, which form a system of scaffolding that maintains cell shape. The building blocks of polynucleic acids are nucleotide monomers. DNA and RNA are examples of polynucleotides. Long polynucleotide chains are wound around each other in the form of a double helix. Double-helical DNA plays an essential role in gene regulation. Polysaccharides are carbohydrate structures that have diverse biological functions: they serve as either structural components (e.g., in the extracellular matrix) or energy storage molecules. They are often covalently attached to proteins to form proteoglycans. The chemical composition and the sequence of the monomeric units dene the primary structure of the biopolymer. Many biopolymers (e.g., proteins) spontane- ously fold into compact shapes as well as form higher order structures, which determine their biological functions and depend in a complicated way on their primary structures. The diversity in the geometry of biopolymer systems at the level of the individual molecule and molecular assemblies is remarkable. Understanding these functions and roles can help to not only elucidate the complexity of biological machinery but also form the basis for development of new therapeutic approaches. Extensive efforts have been devoted to separating the basic monomers as well as more complex structures. In many instances, biopolymer assemblies, some very similar to those observed in nature, can be reconstructed in solution (in vivo), allowing researchers to investigate the structure, dynamics, biological properties, and functions under well-controlled experimental conditions. Handbook of Biopolymer-Based Materials: From Blends and Composites to Gels and Complex Networks, First Edition. Edited by Sabu Thomas, Dominique Durand, Christophe Chassenieux, and P. Jyotishkumar. # 2013 Wiley-VCH Verlag GmbH & Co. KGaA. Published 2013 by Wiley-VCH Verlag GmbH & Co. KGaA. j583
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19 Large-Scale Structural Characterization of Biopolymer ......Large-Scale Structural Characterization of Biopolymer Systems by Small-Angle Neutron Scattering Ferenc Horkay 19.1 Introduction

May 24, 2020

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