Naturally occurring biopolymers

Biopolymers Naturally occurring macromolecules that include proteins, nucleic acids, and polysaccharides. 

Applications. — An article on Biopolymers makes the following statement Biopolymers — naturally occurring macromolecules — are a case apart from the other polymers. The old slogan, what man can do in chemistry has already been done by nature in a more elegant way bears repetition. Man-made polymers are really attempts to simulate the properties of natural polymers. The great activity in the field of polymer synthesis can be summed up as attempts to generate materials (which possess the properties or functions of natural molecules) by short-cut routes that avoid the expense and low availability of natural materials, and circumvent the lengthy time necessary for their isolation. Examples drawn upon include enzymes and their immobilization. 

Proteins, ubiquitous to all living systems, are biopolymers (qv) built up of various combinations of 20 different naturally occurring amino acids (qv). The number of proteins in an organism may be as small as half a do2en, as in the case of the simple bacterial vims M13, or as large as 50,000, as in the human system. Proteins are encoded by the deoxyribonucleic acid (DNA) that is present in all living cells. 

Biopolymers are the naturally occurring macromolecular materials that are the components of all living systems. There are three principal categories of biopolymers, each of which is the topic of a separate article in the Eniyclopedia proteins (qv) nucleic acids (qv) and polysaccharides (see Carbohydrates Microbial polysaccharides). Biopolymers are formed through condensation of monomeric units ie, the corresponding monomers are amino acids (qv), nucleotides, and monosaccharides, for proteins, nucleic acids, and polysaccharides, respectively. The term biopolymers is also used to describe synthetic polymers prepared from the same or similar monomer units as are the natural molecules. 

There are approximately 20 common naturally occurring amino acids, hence 20 different R groups that appear as pendents on the polyamide chain. Many other amino acids have been isolated or prepared, each representing a variation in R. The number of isomeric stmctures is myriad. Protein biosynthesis is mediated by other biopolymers, the nucleic acids. 

Macromolecular Symposia, Vol. 232,1, (February 2005), pp. (1-12), ISSN 1521-3900 Ebringerova, A. Heinze, T. (2000). Xylan and xylan derivatives - Biopolymers with valuable properties, 1 - Naturally occurring xylans structures, procedures and properties.. Macromolecular Rapid Communications, Vol. 21, 9, 0une 2000), pp. (542-556), ISSN 1022-1336... 

Naturally occurring polysaccharides and their derivatives form the predominant group of water-soluble species generally used as thickeners to impart viscosity to treating fluids [1092]. Other synthetic polymers and biopolymers have found ancillary applications. Polymers increase the viscosity of the fi ac-turing fluid in comparatively small amounts. The increase in fluid viscosity of hydraulic fracturing fluids serves for improved proppant placement and fluid loss control. Table 17 summarizes polymers suitable for fracturing fluids. 

Production of all naturally occurring polymers in vivo is catalyzed by enzymes. Polymerizations catalyzed by an enzyme ( enzymatic polymerizations ) have received much attention as new methodology [6-11], since in recent years structural variation of synthetic targets on polymers has begun to develop highly selective polymerizations for the increasing demands in the production of various functional polymers in material science. So far, in vitro syntheses of not only biopolymers but also non-natural synthetic polymers through enzymatic catalysis have been achieved [6-11]. 

Molecular weights of both synthetic and naturally occurring polymers have been obtained by LS almost as a routine measurement. For reasons which are not wholly evident but which probably have historical and medical connotations, sedimentation in the ultracentrifuge seems to be somewhat preferred by workers in the field of biopolymers, although this technique offers no advantages over LS. Indeed LS can frequently provide additional information and is less time consuming. 

Helix-Coil Stability Constants for the Naturally Occurring Amino Acids In Water. XIV. Methionine Paramaters from Random Poly(hydroxypropylglutamine-L-methionine>" Hill, D. J. T. Cardinaux, F. Scheraga, H. A. Biopolymers 1977, IS, 2447. 

In addition to being necessary for all forms of life, biopolymers, especially enzymes (proteins), have found commercial applications in various analytical techniques (see Automated instrumentation, clinical chemistry Automated instrumentation, hemtatology Biopolymers, analytical techniques Biosensors Immunoassay) in synthetic processes (see Enzyme applications, industrial Enzyme applications in organic synthesis) and in prescribed therapies (see Enzyme applications, THERAPEUTICS IMMUNOTHERAPEUTIC AGENTS Vitamins). Other naturally occurring biopolymers having significant commercial importance are the cellulose (qv) derivatives, eg, cotton (qv) and wood (qv), which are complex polysaccharides. 

Tn spite of intensive research by countless numbers of capable scientists for the past 30 years our methods for precise separation and characterization of larger molecules do not have the discrimination needed to solve many of the problems now posed by what we have already learned about the behavior of such substances. This is true even with naturally occurring biopolymers where the amazing selectivity of the synthetic processes of living tissues permits the isolation of preparations which show the behavior expected if the individual molecules of the preparation should be really all of the same size, shape, and composition. Research with biopolymers can therefore be considered in a different category from that so important for industrial polymers since in many cases it relates to single molecular species. The importance of the latter point depends... 

Fig. 5. Structures of the most important chiral modifiers. Not shown are the sugars and biopolymers used. In some cases the naturally occuring compound was derivatized for best effects but very often this was not even necessary.

Teichoic acids (TAs), naturally occurring polyphosphates of substituted glycerol (7) or ribitol (2) in the simpler cases, are biopolymers isolated from the cell walls (wall TAs) or membranes [membrane TAs or lipoteichoic acids (LTAs)] of various Grampositive bacteria ... 

Modification of the biopolymer with naturally occurring molecules in order to obtain completely bio-based materials. 

In addition to synthetic biodegradable polymers discussed so far, naturally occurring biopolymers have also been used for fabricating implantable dmg delivery systems. Examples of natural biopolymers are proteins (e.g. albumin, casein, collagen, and gelatin) and polysaccharides (e.g. cellulose derivatives, chitin derivatives, dextran, hyaluronic acids, inulin, and starch). 

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