Proteolytic catalysts

Copper salts such as CuS04 are potent catalysts of the oxidative modification of LDL in vitro (Esterbauer et al., 1990), although more than 95% of the copper in human serum is bound to caeruloplasmin. Cp is an acute-phase protein and a potent inhibitor of lipid peroxidation, but is susceptible to both proteolytic and oxidative attack with the consequent release of catalytic copper ions capable of inducing lipid peroxidation (Winyard and... 

The Co(m)-complex of cyden, Co(m)Cyc, is one of the most effedive synthetic catalysts discovered so far for the hydrolysis of supercoiled DNAs [59]. The hydrolytic nature of DNA cleavage by the Co(m) complexes of polyamines including cyden has been well documented [57, 58]. The mechanism illustrated in 25 has been proposed [57] for the catalytic action of the Co(m) complexes. Given the remarkable enhancement of proteolytic activity of Cu(n)Cyc upon attachment to PCD [49], we tested the activity of Co(m)Cyc in phosphodiester hydrolysis to see if it is also enhanced greatly upon attachment to PCD derivatives [61, 62]. 

Jencks WP (1917) In Prescott SC (ed) Biochemical catalysts in life and industry proteolytic enzymes. Wiley, New York, pp... 

Resins with good hydrodynamic properties and sorption capadties for proteins and enzymes have been prepared by the polymerization of acrylic acid or methacrylic acid and a crosslinking monomer such as 1,3,5-triacryloylhexahydrotriazine (TAT) in aqueous acetic acid using a radical initiator. Methacrylic add-TAT copolymer prqjared by using a redox catalyst is useful as a cation-exchange resin for selective and reversible sorption of proteolytic enzymes such as terrilytin. 

In the literature a majority of the publications involving enzyme-catalyzed synthesis of polypeptides and polyamides use proteases and related proteolytic enzymes. The data indicate that proteases are good catalysts for the synthesis of oligomers. For high-molecular-weight polymers, the use of protease is more difficult and less reported. 

When the Cu(II) complex of cyclen (AE) was attached to cross-linked polystyrene, the proteolytic activity of the Cu(II) complex of cyclen was enhanced remarkably (111). Poly(chloromethylstyrene-co-divinylbenzene) (PCD) was prepared as a derivative of polystyrene in which all of the styryl residues contained chloromethyl groups. By the substitution of chloro groups of PCD with various nucleophiles, PCD derivative BA was prepared. y-Globulin was hydrolyzed upon incubation with BA, whose half-life was as short as 1 h at 25°C and pH 7 in the presence of excess BA. The rates for hydrolysis of y-globulin by the Cu(II) complex of cyclen itself dissolved in water were also measured. Comparison of rate data collected at the same catalyst concentrations revealed that the proteolytic activity of the Cu(II) complex of cyclen was... 

The catalyst for cleavage of peptide deformylase was searched with a library of catalyst candidates synthesized by the Ugi reaction (Scheme 2) (134). In this multicomponent condensation reaction, the mixture of a carboxylic acid, an amine, an aldehyde, and an isocyanide produces an iV-acyl amino acid amide. The catalyst candidates, therefore, are iV-acylamino acid amides containing various polar and nonpolar pendants as well as the Co(III) complex of cyclen. The Co(III) complex of cyclen (135) was chosen as the proteolytic center in view of the results described in Section V.A. Cyclen with three secondary amines protected with ferf-butyloxycarbonyl (t-boc) groups was incorporated in either the carboxyl or the amine component of the Ugi reaction. Later, the t-boc groups were removed and Co(III) ion was inserted to the cyclen portion. 

Strong mineral acid, such as 6 M HCl, good catalyst for hydrolysis Proteolytic enzymes (proteases) provide catalysis for cleaving specific peptide bonds... 

No other cofactors are required for enzymatic catalysts of this reaction. Amino acid analysis on isolated isoenzymes I and III indicate that the lower molecular weight monomers from I are not proteolytic degradation products of the monomers from III [68], When dimers of I (a ) are mixed with dimers of III ()8y8) an equilibrium concentration of II (afi) is formed. 

Pineapple contains bromelain — a proteolytic, or proteinsplitting, enzyme. Enzymes themselves are specialized protein molecules produced by living systems, and they act as biological catalysts that speed up the numerous reactions that together constitute life. The bromelain in pineapple serves as a defense against predators. It irritates the tissues in the mouth as proteins begin to break down. Bromelain, like all enzymes, is heat-sensitive, and cooking destroys it. Canned pineapple is... 

The manufacture of beer as now practiced is, in fact, much too costly. Malting is an operation which involves considerable losses in nutritive materials. The catalysts which are developed during this part of the manufacture, although very expensive, are far from performing all the necessary work. The amylase of the malt has two functions the one, liquefaction the other, saccharification. Now, these two effects are exerted at differait temperatures, and the saccharification carmot be conducted in the desired way without neglecting the liquefaction. Consequently, undissolved starch always remains in the husks. On the other hand, the proteolytic enzymes are abundant but of a quality not suited to the work desired. They can induce an advanced hydrolysis, but exert only a poor dissolving action. 

It became clear that a 5 -desoxyadenosyl radical mechanism activates the nonfunctionahzed C6 and C9 positions of dethiobiotin involving the Fe4S4 iron sulfur cluster of BioB. Sulfur is recruited from a Fe2S2 iron sulfur cluster that is present in BioB as well. It was speculated that BioB is used as a reactant rather than a catalyst. In vitro experiments, however, demonstrated that biotin synthase is catalytic, but that catalysis puts the protein at risk of proteolytic destruction... 

In the absence of acids or bases peptide bonds are quite resistant to hydrolysis, but their hydrolytic cleavage is extremely accelerated in the presence of proteolytic enzymes. The remarkable catalytic effect of these enzymes tempted many investigators, through a long period of time (Fruton 1982), to adopt them for synthesis, rather than hydrolysis of peptide bonds. Since enzymes are catalysts and merely accelerate the establishment of equilibria, it is possible to use proteolytic enzymes for amide bond formation if the equilibrium of the reaction can be modified. Thus anilides of blocked amino acids could be prepared with the help of papain ... 

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