Protein , denaturation hydrolysis

Partial/complete protein denaturation Covalent alterations Hydrolysis Deamidation Imine formation Racemization Oxidation... 

Sometimes the easiest way to destroy drug-protein binding is to dilute the sample with a physiological saline solution. For instance, for isoxazolyl penicillins with a binding percentage of over 95%, dilution with 9 volumes of 0.9% sodium chloride solution can be sufficient (9). Alternative widely used techniques are based on either protein denaturation or enzymatic/chemical hydrolysis of the drug-protein complexes (10-12). 

Protein and starch digestion, on the other hand, have potent nonpancreatic compensatory mechanisms. Due to the compensatory action of salivary amylase and brush border oligosaccharidases, a substantial proportion of starch digestion can be achieved without pancreatic amylase. Similarly, protein denaturation and hydrolysis is initiated by gastric proteolytic activity (acid and pepsin) and continued by intestinal brush border peptidases, and is thus partly maintained even in the absence of pancreatic proteolytic activity. 

Many workers have studied the influence of enzymatic hydrolysis on the functional properties of various food proteins, and much of this work has recently been reviewed by Richardson (2). However, there seem to be very few reports which quantitatively relate functionality to parameters which characterize the protein hydrolysates per se (e.g. molecular weight). Ricks et al. (3 ) examined the solubility and taste of a number of pure proteins (denatured pepsin, lactoblobulin, a-Sj -, K-, and 8-casein) hydrolysed with... 

The preparation of labeled haptens may occur under more extreme conditions, since protein denaturation is only a factor if the label is an enzyme. The first critical step in hapten labeling is the introduction of a reactive group onto the hapten, which may be done by the alkylation of O or N substituents with haloesters,3 followed by hydrolysis (Eq. 6.1) ... 

If all the prototropic groups of native proteins were normally reactive to acids and bases, this normal reactivity would constitute a significant exception to the well-founded generalization that the functional groups (sulfhydryl, disulfide, phenoxyl) of native proteins are usually less reactive in native proteins than in proteins denatured by any means (Neurath et al., 1944), just as the susceptibility of proteins to hydrolysis by proteolytic enzymes is usually increased by denaturation. 

Northrop carefully tested his enzyme preparations by means of solubility measurements, ultracentrifuge analysis, and electrophoresis, and concluded that they were essentially pure proteins. From measurements of diffusion, denaturation, hydrolysis, and the formation of active enzyme ftom inactive precursor, he concluded that enzymatic activity was a property of the protein molecule itself and was not due to a nonprotein impurity. 

The influence of protein denaturants (such as alcohols, urea and urea derivatives, and quaternary ammonium salts) on the stability of the compact-coil conformation of PMAA is also described. These protein denaturants, when added to aqueous solutions of PMAA, considerably limit the rate of the neutral hydrolysis of 1-benzoyl-3-phenyl-1,2,4-triazole. 

Another important factor affecting storage stability of dehydrated foods is temperature and period of storage. Generally, the storage stability bears an inverse relationship to storage temperature, which affects not only the rate of deteriorative reaction (enzyme hydrolysis, lipid oxidation, NEB, protein denaturation), but also the kind of spoilage mechanism. 

To determine the kinds of residues modified, the aldolase inactivated with 1-[ C] bromopyruvate was first reduced, in the presence of a protein denaturant, with sodium borohydride to convert the ketone group of the incorporated pyruvyl moiety to a hydroxyl group. This was necessitated by the decarboxylation of the pyruvyl moiety (and therefore loss of the C label) during hydrolysis of the protein. ... 

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