Access of enzymes

At temperatures above Tm, chemical and enzymatic degradation of microbial exopolysaccharides is enhanced. The apparent enhanced stability of microbial exopolysaccharides in their ordered confirmation is thought to be due to the glycosidic bonds in the backbone of the polymer which raises the activation energy. This restricted movement would also restrict access of enzymes and chemicals to the backbone. 

The approach by Brennan with collaborators led to notable improvement in the biocompatibility of sol-gel processing. However, there are some disadvantages. Their approach does not exclude the hydrolytic separation of alcohol. Its presence is detrimental for sensitive biopolymers. Furthermore, the two-stage synthesis is accompanied by the significant shrinkage of sol-gel derived nanocomposites. This leads to a decrease in the pore size that sometimes can restrict the accessibility of enzymes to substrates. 

New enzymes for organic synthesis continue to represent a challenge both for those who prepare them as well as for those who finally apply them. The improved accessibility of enzymes as industrial catalysts has led to a large number of practical processes. The times are long past when it was believed that, at best, hydrolases would be suitable for industrial operations. Today, there are examples of practical applications for almost all enzyme classes. 

The acetylation of the lysine side chain neutralizes the positive charge of the lysine and hence will loosen the association between the histone and DNA. This should facilitate greater access of enzymes to the DNA sequence. 

RS4—physically- or chanically modified starch in which the modifications cause changes in the structure of starch chains, which restricts the access of enzymes to these chains. Roasting, extrusion, acetylation, and hydroxypropylation increase... 

The degradation mechanisms depend on abiotic and biotic (type and quantities of microorganisms and other organisms) factors. Variations in the degradation patterns of different samples of PU were attributed to the many properties of PU, such as molecular orientation, crystallinity, and crosslinking and chemical groups present in the molecular chains, which determine the accessibility of enzyme-degrading systems... 

Polymer-supported small peptides as well as the B-chain of bovine insulin were reported to be soluble in water and in some organic scdvents when using PEG derivatives with a molecular mass of 6000gmol to this purpose. Enzymatic investigations showed that this linear soluble support does not restrict the access of enzymes to bound peptides. 

While natural HA has a short residence time in the body, the HA component of the UHMWPE/HA biomaterials should be stable in the body because it is crosslinked and microscopically entangled within hydrophobic UHMWPE, thus limiting the access of enzymes to the HA phase. Zhang et al. [81] examined the biostability of UHMWPE/ HA in hyaluronidase (15 or 150 units/ml) phosphate buffered saline (PBS) solutions. She tested both treated (but not fully consolidated) preforms and fully consolidated UHMWPE/HA samples, the former intended to be a more... 

The morphology of polymers that allow easy access of enzyme to the polymer chain increases the rate of degradation. Low crystallinity samples are degraded faster than those of high crystallinity. 

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