Protein with proteolytic enzymes

Modification of Proteins with Proteolytic Enzymes from the Marine Environment... 

If the virus is treated with proteolytic enzymes the fuzzy layer formed by the viral spikes is removed (Osterrieth, 1965 Compans, 1971 Gahm-berg et al, 1972 Sefton and Gaffney, 1974 Utermann and Simons, 1974). Remnants of both El and E2 are left in the bilayer. These have a hydrophobic amino acid composition, and are soluble in lipid solvents such as chloroform-methanol. The amphiphilic nature of the spike protein is also evident from its capacity to bind Triton X-100 (0.6 g/g protein) which binds to the hydrophobic part to form a water-soluble protein-detergent complex (Simons et al., 1973a). The ability of amphiphilic proteins to bind Triton can be used to separate them from hydrophilic proteins using an extraction procedure recendy described... 

Fontaine et al. (31) presented data comparing the solubility behavior of proteins of peanut and cottonseed meals, proteins of corresponding dialyzed meals, and isolated proteins. While the shapes of the pH/solubility curves for cottonseed and peanut meals differed, the response of proteins to the removal of dialyzable meal constituents was similar. Data indicated the presence of natural materials in both meals which decreased the solubility of meal nitrogen at certain acid pH values but exerted no effect at alkaline pH values. Thus procedures for solubilizing proteins by treatment with proteolytic enzymes should also be designed with consideration of the influence of non-protein constituents. 

Papain is a protein-hydrolyzing (proteolytic) enzyme with an -SH group and an imidazole group at the active site. Write a reasonable structure for a "tetrahedral intermediate" that would be expected to arise during formation of an acyl enzyme intermediate. 

Let us now consider the retarding action of proteolytic enzymes on hydrolysis. Attention should be drawn to the fact that the carbonyl absorption band splits into two parts as a result of interaction of the cured KL-3 with proteolytic enzymes and kidney extract. Evidently it is associated with the specific interaction of the enzyme and urethane group in the polymer, the structure of which resembles the peptide group of a protein molecule. Owing to the specific action of the enzyme, this interaction does not accelerate the hydrolysis of urethane groups but even retards it owing to the shielding effect of the enzyme protein molecule. 

Svec, F. (2006) Less common applications of monoliths I. Microscale protein mapping with proteolytic enzymes immobilized on monolithic supports. Electrophoresis, 27, 947. 

Hydrolysis of Protein. The radioactive, proteinaceous residues from the sulfate-injected insects were separated into equal fractions, one of which was hydrolyzed with acid and the other with proteolytic enzyme. Analyses of unlabeled protein were made after acid or alkaline hydrolysis. 

Figure 13. Solubility and emulsifying properties of proteins in peanut flour treated with proteolytic enzymes. (H) Not treated, pH 6.9 (O) trypsin, pH 7.6 (Q) bromelain, pH 4.5 (9) pepsin, pH 2.0.

Many crystallization reports emphasize the need to use pure proteins to ensure crystal reproducibility. The application of recombinant DNA technology to the production of truncated gene products promises to alleviate many of the difficulties associated with purifying protein fragments produced with proteolytic enzymes. 

Mass spectrometry (MS) permits the identification of proteins by the determination of the exact mass of peptides, and the fragmentation of these peptides to determine the amino acid sequence. Protein samples, such as purified organelles or protein complexes are usually separated by their relative molecular weight on SDS-PAGE gels. The protein bands are visualized by dyes such as Coomassie brilliant blue and then are excised from the gel. The protein-containing gel slices are washed and incubated with proteolytic enzymes such as trypsin and the resultant peptides extracted from the gel-slices. 

Table XVI gives a partial list of native proteins that have been hydrolyzed with proteolytic enzymes. A discussion of the interpretation of each example listed is beyond the scope of this review, but a few comments concerning certain features of proteolysis are ivarranted. The mechanism of enzymatic hydrolysis of native proteins was studied in detail by Tiselius and Eriksson-Quensel (1939), who examined the action of pepsin on ovalbumin. Two mechanisms of proteolysis were considered by these workers. In the first mechanism the enzyme hydrolyzes all susceptible peptide bonds in one substrate molecule before hydrolysis of a second molecule begins. This type of mechanism has been described by Lmderstrpm-Lang (1952) as the all or none type. In the second mechanism, the enzyme hydrolyzes the single, most susceptible bond in all substrate molecules before hydrolysis of other bonds occurs. This mechanism is called the zipper type. Hydrolysis of a protein can proceed by either of the two mechanisms or by a mechanism which has features of both types. General aspects of the problem have been reviewed and theoretical equations which describe the kinetics of ea( h mechanism have been derived (Linderstr0m-Lang, 1952, 1953).

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