Enzymatic proteolysis

Rokka, T., Syvaoja, E.L., Tuominen, J., and Korhonen, H. 1997. Release of bioactive peptides by enzymatic proteolysis of Lactobacillus GG fermented UHT milk. Milch wissenschaft 52 675-678. 

Penas, E., Prestamo, G., Polo, F., Gomez, R. 2006. Enzymatic proteolysis, under high pressure of soybean whey Analysis of peptides and the allergen Gly m 1 in the hydrolysates. Food Chem 99 569-573. 

A useful, yet almost never mentioned aspect of water or buffered extraction is its ability to remove water-soluble metal ions that can hamper a scheduled sample preparation step, for example, enzymatic proteolysis, through enzyme inhibition [45]. 

Although decades of continuing development in the field of instrumentation and application of As and Se speciation have led to landmarks as regards sample preparation methods, no universal approach can fulfil all the requirements of today s speciation analytical challenges. On the other hand, a few key steps have been consolidated in the optimization of sample preparation for materials that have never been analyzed before, namely, methanolic extraction for As speciation and enzymatic proteolysis for Se speciation. 

To assess Se distribution and speciation in Brazil and other types of nuts, the defatted and powdered samples were fractionated into proteins and cytosol as shown by a Bow chart in Figure 21.1 [13, 14], For the evaluation of Se binding to proteins by SEC, protein precipitate was solubilized with SDS-containing acetate buffer. For the speciation of low-molecular-weight (LMW) Se compounds released from proteins, two procedures of protein hydrolysis were applied and the results obtained were compared. It was shown that acid hydrolysis with methane-sulfonic acid allowed for more efferent release of selenomethionine from proteins as compared with enzymatic proteolysis [14],... 

It can be concluded that the bacterial proteinases can be applied to many proplems where extensive enzymatic proteolysis is required. Because of their wide substrate specificity, they are not useful for producing one of the major sets of peptides which are required to provide overlapping sequences within large polypeptides or proteins. On the other hand, where structural studies of small peptides require extensive cleavage at a variety of bonds, the bacterial proteinases are excellent hydrolytic agents. The products of proteinase action are often quite analogous to the products... 

Separation and identification of several thousand proteins are achieved by use of two-dimension electrophoresis (2-DE) coupled to MS. This procedure, which can be automated, involves excision of the protein spots from the 2-DE gel followed by individual enzymatic proteolysis with trypsin and MS analysis of the mixture (Ashcroft, 2003). 

Foreign proteins as well as self-proteins contain dominant and cryptic epitopes (Sercarz et al., 1993 Moudgil Sercarz, 1994). Dominant epitopes of a protein are those epitopes or stretches of peptide that survive enzymatic proteolysis and in addition bind with sufficiently high affinity to MHC molecules to be presented to T cells. Peptide stretches that do not survive antigen processing (e.g. survive enzymatic splicing), that do not bind to MHC molecules, or with too low affinity remain unnoticed and are considered cryptic to... 

Bioactive peptides released by enzymatic proteolysis of various proteins that act as potential physiological modulators of metabolism during intestinal digestion have been reported in recent reports. These peptides usually contain 3-20 amino acid residues, and their activity depends on their amino acid composition and sequence (Pihlanto-Leppala, 2001). Based on their structural, compositional, and sequential properties, they may exhibit different kinds of bioactivities such as antioxidative (Jimg et al., 2005 Kim et al., 2001), antihypertensive (Suetsima et ah, 2004), and immunomodulatory effects (Qien et al., 1995 Tsuruki et al., 2003). 

Serum Albumin Another application of the immunoaffinity chromatography technique was in the analysis of AFBl bound to serum albumin (9). Blood samples were collected on Day 5 from the same individuals who participated in the study described above. Serum albumin was selectively isolated from blood and subjected to enzymatic proteolysis using Pronase. Aflatoxin specific adducts were purified by immu-noaffinity chromatography and quantified by competitive radioimmunoassay. A highly significant correlation of adduct level with AFBl intake (r = 0.69, P less than 0.000001) was observed. From the slope of the regression... 

The polarographic method is very practical and sensitive for the assessment of enzymatic proteolysis in the serum. If serum protein or albumin is used as substrate, the results obtained are not strictly specific use of suitable synthetic substrates could, however, solve the problem of specificity in the future. There follows a brief survey of present faculties of polarography. 

Changes in the concentrations of proteins are determined, using LC-MS, by the relative amoimts of the light or heavy peptides after the samples have been combined, and the proteins isolated and subjected to enzymatic proteolysis. 

We demonstrated that proteic and/or carbohydrate coating can render an enzyme less susceptible to thermal denaturation, enzymatic proteolysis and immunological attack. Carbohydrates or proteins can also be fixed in order to target the enzyme to the right tissue(s) or cell(s). Little is still known about the in vivo behaviour of such molecular associations but the promises of enzyme technology for therapeutic applications (lysosomal storage diseases for instance) are so great as to stimulate such studies in the near future. 

ProLastin polymers are a family of protein-based materials w hose resorption rate in vivo can be controlled by adjusting the sequence and not just the composition of the polymer (Cappello et al, 1995). These adjustments can be made so as to cause little change in the formulation characteristics of the materials, their physical forms, or their mechanical properties. They have good mechanical integrity with no need for chemical crosslinking. They degrade by enzymatic proteolysis and are presumed to resorb by surface erosion. Their breakdowm products are peptides or amino acids w hich are electroneutral at physiological pH and cause no undue inflammation or tissue response. 

Hydrolysis studies are often done with esters because amides are extremely unreactive. For example, a peptide bond of a proline with another amino acid is usually very resistant against enzymatic proteolysis. The HIV protease... 

Mihalyi, E. (1978) Proteolytic enzymes, enzymatic proteolysis—general considerations, in Application of Proteolytic Enzymes to Protein Structure Studies, 2nd ed., 1,43-149... 

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