Mild proteolysis

Superficially, the lambda repressor protein is very different from lambda Cro. The polypeptide chain is much larger, 236 amino acids, and is composed of two domains that can be released as separate fragments by mild proteolysis. In repressor the domain responsible for dimerization is separate from the... 

The latter is dependent on interplay between the degree of permeability of the cell/tissue and the size of the probe. In practice, probes with a median size of 200-400 bp are suitable for cells/tissues fixed in aldehyde and subjected to varying degrees of proteolysis (see Section 3.). I have found that fixation of cells m aldehyde followed by mild proteolysis produces the best results. 

The proteolysis of cellulases has been previously investigated. Nakayama et al. (14) found that mild proteolysis of endoglucanase from T. reesei by a protease prepared from the same fungus resulted in cellulase enzymes which still possessed cellulolytic activity. Earlier, Eriksson and Petterson (24) investigated the effect of various proteolytic enzymes on the cellulase activities on Penicillium notatum. They found that different proteases affected enzyme activities to different degrees. 

Cytochrome c, is an amphiphilic protein with a molecular weight of 28-31000. Weiss et al. [212] found that it may be isolated only with the help of a detergent. However, by mild proteolysis they could release the haem-binding domain from the rest of the protein. This segment is soluble in aqueous solutions. The amino acid sequence of the bovine protein [181] shows that it has only one continuous hydrophobic segment that is close to the C-terminus. This segment probably acts as an anchor to the membrane. The covalently bound haem is located in the water-soluble part, with its plane perpendicular to the membrane plane [206], The two-domain structure makes the architecture of cytochrome c, very similar to that of microsomal cytochrome [213]. 

Attempts have been made to devise conditions of mild proteolysis to discover whether fragments of the whole molecule are active. Apo-pig M4-LDH is more susceptible to proteolysis than apo-H -LDH, although no active cleavage products were found (192). If the enzyme-NAD-sulfite complex is treated with trypsin, then 90% enzymic activity is retained... 

The existence of flexible regions in ribosomal proteins can be explored by studying the action of proteolytic enzymes under mild conditions. It has been found that many E. coli ribosomal proteins consist of two domains one compactly folded and resistant to proteolysis, the other flexible and vulnerable to proteases (Littlechild et al, 1983). Some proteins (S15, S16, S17, and L30) are very resistant whereas others (S2, S6, S9, L2, L27, L29, and L33) are completely degraded without the appearance of discrete fragments. The remaining proteins yield fragments of various size under these conditions. 

Enzymatic Mild coupling under aqueous conditions without the need for sidechain protection Competing proteolysis limits usefulness... 

Endogeneous and exogeneous ribonucleases have been used also to reduce NA under mild conditions (68). However, extensive proteolysis during incubation for RNA hydrolysis and the cost of the enzymes present sizable drawbacks (68,87). 

A glycoprotein that reacted with P. vulgaris lectin is secreted in all human saliva and ovarian-cyst fluid.739 Binding to P. vulgaris lectin was abolished by proteolysis (with trypsin or pronase), or mild, alkaline hydrolysis, but was unaffected by sequential digestion with neuraminidase (all detectable sialic acid was liberated) and /3-d-galactosidase (less than 1% of the galactose was released).739... 

Ehetary proteins may escape digestion in the mildly acidic stomach of the human newborn. After feeding, the pH of the infant s stomach may remain near neutral or drop to only pH 4.0, in contrast with the pH of 2.0 reached in children and adults after eating. The output of pepsin, the protease of the stomach, also may remain low for the first several months of life. Consequently, proteins may escape acid denaturation and proteolysis in the shtmach of the newborn. Therefore, proteolysis by pancreatic proteases assumes increased importance. 

G bands are produced when metaphase chromosomes are subjected briefly to mild heat or proteolysis and then stained with Giemsa reagent, a permanent DNA dye (Figure... 

Enzymatic hydrolysis of proteins results in changing the molecular mass of the molecules. However, the effects of protein size on the hydrophobic behavior of amino acids are of great importance [132]. There is a meaningful relationship between hydrophobicity (which may affect the surface of the molecule) and functionality of food proteins [11,133] proposed using the term relative surface hydrophobicity. The proteolysis should be carefully limited for improving the functional properties of food proteins [147]. Mild hydrolysis improves functionality of proteins, while extensive hydrolysis depresses it [139,148],... 

Deamidation of proteins is important for improving functional properties of the product under mild reaction conditions. But enzymatic deamidation of proteins has not had real attention until recently. Kato et al. [155] developed a method for enzymatic deamidation of food proteins by treatment with proteases at pH 10. Salt and disulfide reducing agents have little effect on soy protein deamidation. Heat treatment and proteolysis of soy proteins are the major factors affecting deamidation [156]. 

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