Biopolymers exceptional properties

With the exception of starch, many biopolymers cannot provide nutrition for humans and other omnivorous animals. In human foods biopolymers are used as additives that can improve texture, viscosity, fiber content, and other properties of prepared foods, without providing direct nutritional values. Examples of such utilization are the addition of pectins, agar, and other gums to foods to achieve thickening and gelling effects. Another example of potential large-scale utilization of cell wall biopolymers is the dramatic improvement in the texture and rising of breads prepared from com and other starches by the addition of xylans (78). 

Macromolecules are very much like the crystalline powder just described. A few polymers, usually biologically-active natural products like enzymes or proteins, have very specific structure, mass, repeat-unit sequence, and conformational architecture. These biopolymers are the exceptions in polymer chemistry, however. Most synthetic polymers or storage biopolymers are collections of molecules with different numbers of repeat units in the molecule. The individual molecules of a polymer sample thus differ in chain length, mass, and size. The molecular weight of a polymer sample is thus a distributed quantity. This variation in molecular weight amongst molecules in a sample has important implications, since, just as in the crystal dimension example, physical and chemical properties of the polymer sample depend on different measures of the molecular weight distribution. 

Biopolymers in Chiral Chromatography. Biopolymers have had a tremendous impact on the separation of nonsupernnposable. mirror-image isomers known as enantiomers. Enantiomers have identical physical and chemical properties in an achiral environment except that they rotate the plane of polarized light in opposite directions. Thus separation of enantiomers by chromatographic techniques presents special problems. Direct chiral resolution by liquid chromatography (lc) involves diastereomenc interactions between the chiral solute and the chiral stationary phase. Because biopolymers are chiral molecules and can form diastereomeric... 

Oleivera et al. reported PHB production by R. eutropha using agro-industrial residues. The PHB productivity and content were 4.9mg/g medium in 60 h and 39%, respectively. Production was carried out using soy cake alone or supplemented with sugarcane molasses. The results obtained showed that the biopolymer obtained by SSF has similar properties as commercial PHB, except for the higher molar mass and the... 

Although the list of transmethylation reactions in which S-adenosylmethionine can function as the methyl donor could now undoubtedly be greatly expanded, the more recently added reactions, with the exception of the carbon methylations discussed below (Section II,C,6), appear from the chemical point of view to be further examples of types of reactions which were already known. Therefore, no complete compilation will be attempted. From the physiological standpoint, on the other hand, some of the reactions recently studied may be of great interest. For example, systems have now been reported for the enzymic methylation of RNA (Srinavasan and Borek, 1964 Rodeh et al, 1967), DNA (Oda and Marmur, 1966 Kalousek and Morris, 1969), pectin (Kauss and Hassid, 1967), and protein (Comb et al, 1966 Paik and Kim, 1968 Liss et al, 1969). The specific modifications of the properties of these biopolymers consequent to methylation may, of course, be important in... 

This type of separation is extremely useful for any kind of complex samples that are difficult to separate, identify comprehensively, or fully deformtjlate. This is most often the case for synthetic, natural, and biopolymers (monodisperse proteins are one well-known exception), which possess coexisting mtdtiple property... 

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