Proteases/proteinases

Peptidases are enzymes that catalyse the hydrolysis of peptide bonds - the bonds between amino acids that are found in peptides and proteins. The terms protease , proteinase and proteolytic enzyme are synonymous, but strictly speaking can only be applied to peptidases that hydrolase bonds in proteins. Because there are many peptidases that act only on peptides, the term peptidase is recommended. Peptidases are included in subclass 3.4 of enzyme nomenclature [1,5]. 

Proteases (proteinases, peptidases, or proteolytic enzymes) are enzymes that break peptide bonds between amino acids of proteins. The process is called peptide cleavage, a common mechanism of activation or inactivation of enzymes. They use a molecule of water for this, and are thus classified as hydrolases. 

Because of their very complex chemical structures and heterogeneity, melanins are difficult to extract, separate, and characterize from tissues. Eumelanins are insoluble in water and organic solvents. They can be extracted from tissues with strong chemicals that are capable of removing lipids, proteins, and other tissue components but also lead to the formation of degradation products. Enzymatic procedures were developed for the isolation of eumelanins from mammalian hair and irises. The first step is sequential digestion with protease, proteinase K, and papaine in the presence... 

Enzymatic synthesis of aliphatic polyesters was also achieved by the ringopening polymerization of cyclic diesters. Lactide was not enzymatically polymerized under mild reaction conditions however, poly(lacfic acid) with the molecular weight higher than 1 x 10" was formed using lipase BC as catalyst at higher temperatures (80-130°C). Protease (proteinase K) also induced the polymerization however, the catalytic activity was relatively low. 

Lactide was polymerized by lipase PC in bulk at high temperature (80-130°C) to produce poly(lactic acid) with Mw up to 2.7 x 105 [64, 65]. The molecular weight of the polymer from the D,L-isomer was higher than that from the d,d- and L,L-ones. Protease (proteinase K) also induced the polymerization of lactide, however, the catalytic activity was relatively low. 

An investigation into the beneficial properties of Chryseobacterium sp. that might confer freeze-thaw protection to itself, as well as to other bacteria, showed that these cultures had IR inhibition activity no large ice crystals could be seen in capillary tubes after the frozen solutions containing Chryseobacterium sp. cultures had been left overnight at -6°C (Figure 4). Furthermore, this IR inhibition activity appeared to be conferred by a protein since treatment with a protease, proteinase K, abolished this effect ( not shown). 

Protease Proteinase (= any enzyme that catalyses the spHtting of interior peptide bonds in a protein). [EU]... 

Study of heparin binding to thrombin, 56 low-density lipoproteins, lipoprotein lipase, circulatory serine proteases, proteinase inhibitors, heparin-binding growth factors, blood vessel-associated proteins (fibronectin and laminin) and binding to cells and tissues. Study of anticoagulant activity and the modulation of the structure, function and metabolism of many proteins and en-2ymes. 

Betzel, C., Gourinath, S., Kumar, P., Kaur, P., Perbandt, M., Eschenburg, S., Singh, T.P., 2001. Structure of a serine protease proteinase K from Tritirachium album limber at 0.98 A resolution. Biochemistry 40, 3080—3088. 

The human organism is not able to use dietary proteins as such. They must be hydrolysed into single amino acid molecules before they can be absorbed. The hydrolysis of proteins (mostly denatured proteins) is catalysed by proteolytic enzymes called proteases (proteinases or peptidases), which have relatively high substrate specificity. They catalyse the hydrolysis of interior peptide bonds to form peptides of different sizes (endopeptidases such as pepsin, trypsin and chymotrypsin) or attack the terminal amino acids (exopeptidases). Hydrolysis of the N-terminal amino acids is... 

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