Proteolysis enzymes

Fig. 4 Identification of alkyne-tagged P-lactone probes that target ClpP in S. aureus using click-chemistry, in-gel fluorescence and mass spectrometry. Subsequently, lead compounds were administered to 5. aureus and changes to the global bacterial proteome monitored. Particularly, changes to the levels of haemolysis and proteolysis enzymes (haemolysins, proteases, lipases and...

Frequently a third enzymatic digestion is necessary to eliminate all the possible ambiguities. Using trypsin as a proteolysis enzyme allows one partially to distinguish Lys from Gin, two isobars. In fact, the trypsin specifically cleaves on the C-terminal side of Lys and Arg, so all the amino acids with mass 128 ending a peptide can be identified as Lys. However, the absence of a cleavage cannot be used as proof in identifying an amino acid... 

Manga- nese Carboxylate, phosphate, imidazole Glycolysis and proteolysis enzymes... 

Protenoids Proteoglycans Proteolysis Proteolytic enzymes Proteus... 

Selective proteolysis by acid/enzyme treatment is an optional method for IgG (iv). 

Neurokinin effects are terrninated by proteolysis. In vitro acetylcholinesterase (ACE) and enkephalinase can hydrolyze substance P. However, there appears to be no clear evidence that either acetylcholinesterase or ACE limit the actions of released substance P. Enkephalinase inhibitors, eg, thiorphan, can augment substance P release or action in some systems but the distribution of enkephalinase in the brain does not precisely mirror that of substance P. There appears to be a substance P-selective enzyme in brain and spinal cord. 

Enzyme Sta.bihty, Loss of enzyme-catalytic activity may be caused by physical denaturation, eg, high temperature, drying/freezing, etc or by chemical denaturation, eg, acidic or alkaline hydrolysis, proteolysis, oxidation, denaturants such as surfactants or solvents, etc. pH has a strong influence on enzyme stabiHty, and must be adjusted to a range suitable for the particular enzyme. If the enzyme is not sufficiendy stable in aqueous solution, it can be stabilized by certain additives a comprehensive treatment with additional examples is available (27). 

There are two basic strategies for enzyme-catalyzed peptide synthesis equiUbrium- and kineticaHy controlled synthesis. The former is the direct reversal of proteolysis and involves the condensation of an amino component with unactivated carboxyl component. The latter proceeds by the aminolysis of an activated peptide ester. 

The shell of all picomaviruses is built up from 60 copies each of four polypeptide chains, called VPl to VP4. These are translated from the viral RNA into a single polypeptide, which is posttranslationally processed by stepwise proteolysis involving viraily encoded enzymes. First, the polypeptide chain is cleaved into three proteins VPO (which is the precursor for VP2 and VP4), VPl and VP3. These proteins begin the assembly process. The last step of the processing cascade occurs during completion of the virion assembly the precursor protein VPO is cleaved into VP2 and VP4 by a mechanism that is probably autocatalytic but may also involve the viral RNA. VPl, VP2, and VP3 have molecular masses of around 30,000 daltons, whereas VP4 is small, being 7000 daltons, and is completely buried inside the virion. 

A topical enzyme aids in the removal of dead soft tissues by hastening the reduction of proteins into simpler substances. This is called proteolysis or a proteolytic action. The components of certain types of wounds, namely necrotic (dead) tissues and purulent exudates (pus-containing fluid), prevent proper wound healing. Removal of this type of debris by application of a topical enzyme aids in healing. Examples of conditions that may respond to application of a topical enzyme include second- and third-degree bums, pressure ulcers, and ulcers caused by peripheral vascular disease An example of a topical enzyme is collagenase (Santyl). 

In mammalian cells, the two most common forms of covalent modification are partial proteolysis and ph osphorylation. Because cells lack the ability to reunite the two portions of a protein produced by hydrolysis of a peptide bond, proteolysis constitutes an irreversible modification. By contrast, phosphorylation is a reversible modification process. The phosphorylation of proteins on seryl, threonyl, or tyrosyl residues, catalyzed by protein kinases, is thermodynamically spontaneous. Equally spontaneous is the hydrolytic removal of these phosphoryl groups by enzymes called protein phosphatases. 

NCD-4 is a nonfluorescent carbodiimide derivative that forms a fluorescent adduct with the Ca -ATPase, accompanied by inhibition of ATPase activity and phos-phoenzyme formation [376-378]. Ca protected the enzyme against the inhibition by NCD-4 and reduced the extent of labeling, suggesting that the reaction may involve the Ca " " binding site. The stoichiometry of the Ca -protected labeling was i 2mole/mol ATPase. The fluorescence emission of the modified Ca -ATPase is consistent with the formation of a protein bound A-acylurea adduct in a relatively hydrophobic environment. After tryptic proteolysis of the NCD-4 labeled ATPase the fluorescence was associated with the A2 band of 24 kDa [376,379]. 

Although a few mechanisms have so far been proposed to explain the antimicrobial properties exhibited by proanthocyanidins (e.g., inhibition of extracellular enzymes) [86], Jones et al. [83] postulated that their ability to bind bacterial cell coat polymers and their abihty to inhibit cell-associated proteolysis might be considered responsible for the observed activity (Table 1). Accordingly, despite the formation of complexes with cell coat polymers, proanthocyanidins penetrated to the cell wall in sufficient concentration to react with one or more ultra-structural components and to selectively inhibit cell wall synthesis. Decreased proteolysis in these strains may also reflect a reduction of the export of proteases from the cell in the presence of proanthocyanidins [83]. 

Proteolysis The hydrolysis of proteins, usually by enzyme action, into simpler substances. 

Zymogen A proenzyme the inactive or nearly inactive precursor of an enzyme that is converted into an active enzyme by proteolysis. 

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