Poly , natural

Several other polyamides are derived from natural poly(amino acids) that are subject to a subsequent synthetic treatment. Examples are casein, groundnut protein fiber, and zein, which after a treatment with formaldehyde led to new materials with better mechanical/solubility properties. For example, casein is a mixture of several proteins that forms 3% of milk (as casein calcium salt). Casein can be fractionated into simpler proteins designated as a, 3, y, and k [37]. The amino acid content of casein is similar to... 

For natural poly-APS alkaloids (77), matrix assisted laser desorption ionization-time-of-flight (MALDI-TOF) spectrometric analysis showed that the compounds comprised a mixture of two polymers with molecular weights centred at around 5520 Da and 18900 Da and with a low degree of polydispersity [34]. 

A by synthetic compounds was also tested. Only two monomers and a tetramer caused a weak reversible inhibition, while natural poly-APS showed moderate inhibition with an IC50 of 4 pg/mL. Finally, haemolytic assays showed that albeit active, synthetic compounds are far less haemolytic compared to natural poly-APS. 

Many ionic poly(saccharides), such as heparin, chondroitin sulfates, dextran sulfate, and natural poly(saccharides), such as dextran, dextrin, pullulan, and their charged derivatives have been used as mobile phase additives for the separation of different enantiomers. Figure 10.10 [191,192,205,206]. Dextrins were found to have a wide application range, thought to be due in part to their helical structures. Enantiomer-chiral selector complexes seem to be weaker than for cyclodextrins, and it has not been demonstrated that enantiomer separations obtained by the poly(saccharide) chiral selectors cannot be obtained using cyclodextrins. Natural poly(saccharides) are typically complex mixtures of homologues and isomers, with a composition that can vary for different sources, resulting in differences in enantioselectivity. 

Chaga G., Bochkariov D.E., Jokhadze G.G., Hopp J. and Nelson P. Natural poly-histidine affinity tag for purification of recombinant proteins on cobalt(II)-carboxymethylaspartate crosslinked agarosa, J. Chromatogr. A, 864, 1999, 247. 

The equilibrium properties in dilute aqueous solution of weakly ionized polysaccharides, e.g. carboxylated natural poly= saccharides, have not been so thoroughly investigated in comparison with other natural and synthetic polyelectrolytes. For instance, a detailed thermodynamic characterization of acid ionization and of counterion binding in terms of combined experimental potentiometric, calorimetric and volumetric data has not been achieved so far for the above types of polysaccharides. Such a description, however, is of obvious relevance for a better understanding of structure-conformation dependent solution properties for this important class of biopolymers. 

In general, the properties of a biosystem and a synthetic polymer as well as the nature of the biological medium dictate the degree and type of interaction between a biostructure and a polymer. The biocompatibility of synthetic polymers depends on their chemical nature, physical state, and macroscopic form, which can be modified by functionalization of the polymer skeleton. Many biopolymers, such as proteins and nucleic acids, are natural poly electrolytes. Similarly, the outer cell membrane of living cells has charged groups. The biological medium is an electrolyte with an aqueous phase. Therefore, electrostatic... 

Examination of hydrolytic degradation of natural poly((i )-3-hydroxybu-tyrate) in vitro is a very important step for understanding of PHB biodegradation. There are several very profound and careful examinations of PHB hydrolysis that was carried out for 10-15 years [25-28], Hydrolytic degradation of PHB was usually examined under standard experimental conditions simulating internal body fluid in buffered solutions with pH = 7.4 at 37°C but at seldom cases, the higher temperature (55°C, 70°C, and more) and other values of pH (from 2 to 11) were selected. 

Scandola, M. et al. Polymer blends of natural poly(3-hydroxybutyrate-co-hydroxyval-erate) and a synthetic atactic poly(3-hydroxybutyrate). Characterization and biodegradation studies. MacTOwofe. 1997, 30,2568-2574. 

Chitosan is a linear randomly distributed, binary heteropolysaccharide prepared by deacetylation of chitin, a linear polymer of P(l-4) linked N-acetyl-o-glucosamine units composed of mucopolysaccharides and amino sugars. It is a natural poly-(aminosaccharide), having structural characteristics similar to glycosaminoglycans. 

Scandola, M., Focarete, M. L., Adamus, G., Sikorska, W., Baranowska, I., Wierczek, Sabina, Gnatowski, M., Kowalczuk, M., Jedlihski, Z., Polymer blends of natural poly(3-hydroxybulyrate-co-3-hydroxyvalerate] and a synthetic atactic poly(3-hydroxybulyrate]. Characterization and biodegradation studies. 9, 2568-2574 (1997],... 

Gammas, S., Guerin, Ph., Girault, J., P., Holler, E., Cache, Y., Vert, M., 1993, Natural poly(L-malic acid) NMR shows a poly(3-hydroxy acid)-type structure. Macromolecules 28 4681-4684. 

The results of the present study revealed that natural poly(3-hydroxyalkanoate)s and their blends with synthetic atactic poly [(R,S)-3-hydroxybutanoic acid] degrade in natural environment, and the rate of biodegradation process depends on their composition, the nature of environment and the specific microorganisms. 

Abstract Hyphenation of electrospray ionization witii ion-trap multistage mass spectrometry (ESI-MS°) provides charactoisation of subtle molecular structure of both syntiietic and natural aliphatic polyesters as well as oligomeric products of their biodegradation. Implementation of multisti e MS technique for structural studies of the novel bio-inspired polymers including poly[(R,S)-3-hydroxybutyrate], a-PHB, telechelics and a-PHB conjugates with oligopeptides has been demonstrated. The novel results concerned with evaluation of the subtle structure of macroinitiators obtained by partial depolymerisation of selected natural poly(3-hydroxyalkanoate)s, PHA, are also presented. 

Kowalczuk, M., Adamus, G., Sikorska, W., Htkzer, B., Borcakli, M., Atkin, A.H., 2000, Novel biodegradable packaging materials based upon atactic poly[(R,S)-3-hydroxybutyrate] and natural poly(hydroxyalkanoate)s, Proc. International Food Biopack Conference , Copenhagen, p. 39. 

Fig. 1 Representative examples of natural poly- and oligosaccharide sequences...

Another sweetener with some similarities to sorbitol is xylitol. Xylitol is a natural poly alcohol that can be isolated from sources such as birch trees and fibers of corn husks. Xylitol is used for some of the same reasons as sorbitol xylitol can be consumed safely by diabetics and is even more effective than sorbitol in preventing cavities in teeth. However, it is more expensive than sorbitol and there is anecdotal evidence that xylitol is toxic in dogs. 

New diblock copolymers of selected PHAs (PHB, PHBV, PHO) with atactic poly[(J ,5 )-3-hydroxybutyrate] (a-PHB) were obtained by using low-molecular weight macroinitiators derived from natural poly(3-hydro-jyalkanoates), which contain olefinic units and activated by 18-crown-6 ether carbojylic end groups. These new polymers are suitable for use as blend compatibilizers. ... 

Natural poly (amino acids) are ionic polymers having only one type of amino acid joined together with amide linkages. When used as a biomaterial, polyfy-glutamic acid) (yPGA) and poly(L-lysine) are the two most commonly studied natural poly(amino acids). 

Scandola M, Focarete ML, Prison G (1998) Simple kinetic model for the heterogenous enzymatic hydrolysis of natural poly(3-hydroxybutyrate). Macromolecules 31 3849-3851... 

Natural poly(amino add)s, such as cyanophycin, poly( -L-lysine) and poly-y-glutamic acid, are biodegradable ionic polymers. These are polydispersed molecules that consist of a-amide linkages, P- and y-carboxylic groups and -amino groups. 

Aromatic imide groups are known to be nearly planar, rigid, polar, and thermostable. However, aromatic imide structures are also known to be non-mesogen in nature. Poly(ester-amide) (PEI) derived from N- (4 -carboxyphenyl) trimellitimide and aliphatic spacers are not thermotropic, whether the spacer used is chiral or not. Semi-aliphatic spacers are observed to exhibit both a smectic and a nematic LC phase in the resultant thermotropic PEIs. The semi-aliphatic chiral spacers exhibit both chiral smectic phase (A or C ) and cholesteric phase. Such a chiral smectic LC-phase, which may be ferroelectric in nature, is extremely rare for LC-main-chain polymers [27]. It is a particular advantage of polar imide mesogens to favor the formation of layer-structures when combined with non-polar species [28]. 

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