Protein hydrolysis effects

Figure 2. Effect of ozone on uptake and incorporation of -leucine into protein by cotton cotyledon leaf discs. Plants were exposed to 0.4 ppm Os for 1 hr, 24 hr prior to experiments. Discs were floated on buffer and incubated in -leucine for up to 4 hr and were then transferred to excess cold leucine to chase the incorporated C-leucine for a subsequent 24 hr period. The data show that ozone-treated tissue incorporated more leucine into protein but do not indicate real differential effects on protein hydrolysis.

Amino acid analysis is fraught with literally dozens of pitfalls. For novel protein ingredients, those that have undergone chemical modification, or ones that have been subjected to high heat, conventional methods for protein hydrolysis may or may not be effective. It may be necessary to evaluate different hydrolysis methods to determine which provides the best recovery. 

Membranes, for electroblots, 185-198 Metallopeptidases, 365 Methanol, in protein electroblots, 185-198 Methionine digestibility of, 135 hydrolysis, effect on, 134 Methylation... 

Sequence analysis of proteins using electroblotting, 189-190 Serine, hydrolysis, effect on, 134 Serine peptidases, 365 Sesame oil, properties and composition of, 474 (table)... 

The amino acid composition of keratin, the protein of hair and wool, includes a greater-than-average proportion of the sulphur-containing amino acid, cystine. Since this is the least soluble of the protein amino acids it can readily be isolated after carefully neutralising an acid hydrolysate of hair (Expt 5.187). Protein hydrolysis is usually effected by boiling for about 10-20 hours with 20 per cent hydrochloric acid. The hydrolysis of hair for the isolation of cystine is, however, best achieved using a mixture of hydrochloric and formic acids. 

Proteolytic modification has special importance for the improvement of solubility of proteins. This effect becomes significant even after very limited proteolysis. Hydrolysis of casein to DH of 2 and 6.7% with Staphylococcus aureus V8 protease increased the isoelectric solubility to 25 and 50%, respectively (Chobert et al., 1988a). However, it should be noted that the solubility profiles were not identical, due to a shift of the isoelectric point of the modified proteins. Solubility of a protein hydrolysate depends on the enzyme used (Adler-Nissen, 1986a). Protamex (a Bacillus proteinase complex) hydrolysates of sodium caseinate (DH 9 and 15%) displayed 85-90% solubility between pH 4 and 5 (Slattery and FitzGerald, 1998). 

Under certain conditions, the stress-70 proteins can participate in the renaturation of denatured or inactivated proteins. The renaturation capabilities of E. coli dnaK protein have been most extensively documented. It has been shown that in vitro, dnaK can protect E. coli RNA polymerase from aggregation when the polymerase is incubated at elevated temperatures that would normally result in loss of activity, and, further, that dnaK can disaggregate and reactivate polymerase, once it has been inactivated by heat denaturation (Skowyra et al., 1990). These activities are absolutely dependent on ATP hydrolysis. The mutant dnaK756 protein is effective in protecting active RNA polymerase against heat inactivation, but is incapable of disaggregating and reactivating polymerase, once it has been heat inactivated. 

Konrad, G., Kleinsclamidt, T., Rohenkohl, H., and Reimerdes, E.H. (2005). Peptic partial hydrolysis of whey protein concentrate for modifying tire surface properties of whey protein. II. Effects on the emulsifying and foaming properties. Milchwissenschaft 60,195-198. 

Functional properties of food protein are sensitive to changes in the size of the protein molecule, structural conformation, and the level and distribution of ionic charges. They can be modified, both enzymatically and nonenzymatically, by reactions such as protein hydrolysis, denaturation, ionization, and cross-linking. Enzymatic modifications are considered safer for food uses and therefore more desirable. However, many nonenzymatic methods have been proven safe and, because of their simplicity and great effectiveness, they are often the method of choice. Specifically, food proteins have been modi-... 

Achouri, A. W. Zhang X. Shiying. Enzymatic hydrolysis of soy protein and effect of succinylation on the functional properties of resulting protein hydrolysates, Food Res. Int. 1998,31, 617-623. 

Inversion of Sucrose. Many hydrolytic reactions, including the decomposition of esters, are reversible but others such as sucrose inversion and protein hydrolysis, though not necessarily complete, have not been reversed. The heat effects of these reactions, however, are important. The inversion of sucrose, for example, is an exothermic reaction with AH at 25°C approximately —3.6 kg-cal per mole. ... 

Hydrolysis of proteins is effected by acids, bases, and certain enzymes. The extent to which the cleavage takes place is determined, in the case of acids, by their concentration, the temperature, and the length of time during which the action is allowed to take place. In the case of enzymes, the results are determined by the nature of the enzyme. Pepsin, which is present in the gastric juice, and trypsin, the enzyme of the pancreatic fluid, have been much studied. Pepsin in the presence of hydrochloric acid converts proteins into peptones trypsin brings about hydrolysis to amino-acids. 

Otte, J., Shalaby, S. M., Zakora, M., Pripp, A. H., El-Shabrawy, S. A., Angiotensin-converting enzyme inhibitory activity of milk protein hydrolysates Effect of snbstrate, enzyme and time of hydrolysis, Int. Dairy J., 17, 488, 2007. 

Cellobiose must be cleaved into its constituent monosaccharides in order to be metabolized by . coli. There are two main ways in which this reaction can occur, hydrolysis and phosphorolysis. P-Glucosidase and cellobiose phosphorylase from Saccharophagus degradans were expressed in E. coli. The results showed that phosphorolysis cells tolerate common inhibitors (sodium acetate) more effectively and produce recombinant proteins more effectively than hydrolysis cells. However, hydrolysis cells utilize xylose more effectively in combination with cellobiose [192]. 

A similar mode of action on the above photosynthetic parameter has been reported about another growth regulator-Jasmonic acid (JA) (10). To a certain extent the action of JA is similar to the inhibiting effect of ABA on the processes of germination and ageing, and also similar in the maner of effect on the stomata and on the protein hydrolysis (14, 17). In its chemical structure and methods of synthesis JA is very close to the group of the prostanoids which, in the case of animals are known to belong to the class of stress-related hormones (19). 

In only a few instances has the possibility of a diffusible or extractable factor been demonstrated. Protein hydrolysis in detached cotyledons of C. maxima is somewhat enhanced when these organs are incubated in a liquid medium together with excised embryonic axes [116]. The inference from this result is that the axis produces a hormonal factor which promotes metabolism in the cotyledons. A hormonal factor also seems to diffuse into the incubation medium bathing P. ponderosa embryos since this medium, when applied to isolated megagametophytic tissue, stimulates 44% more isocitrate lyase than in the control tissue [13]. Similarly, a promotive extract obtained from Ricinus (castor bean) embryos increases the activity of extractable fructose-1,6-diphos-phatase in isolated endosperm of this seed [100]. It should be recognized, however, that these effects are nowhere near as dramatic as the action of cereal embryonic diffusates and extracts upon their endosperm. Moreover, some of the experiments whose results have just been described were not rigorously carried out and are open to serious criticisms (see below, Sect. 7.2.3). It can be stated, in summary, that no embryonic or axial hormonal influence comparable to that exhibited by certain cereal grains has yet been found in other seeds. 

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