Proteases synthesis

There are, indeed, many biological implications that have been triggered by the advent of fullerenes. They range from potential inhibition of HIV-1 protease, synthesis of dmgs for photodynamic therapy and free radical scavenging (antioxidants), to participation in photo-induced DNA scission processes [156, 157, 158, 159, 160, 161, 162 and 163]. These examples unequivocally demonstrate the particular importance of water-soluble fullerenes and are summarized in a few excellent reviews [141, 1751. 

Scheme 2 Statine Analogues Used as Inhibitors of Aspartyl Protease Synthesis...

PRP depletes cells of NAD+ at vesicating doses of sulphur mustard, leading to the inhibition of glycolysis, stimulation of the NADP-dependent, hexose monophosphate shunt and cell death (Papirmeister et al., 1984,1985). Stimulation of this latter enzyme pathway has also been associated with enhancement of protease synthesis and release, resulting in localized subepidermal blister formation in the skin (Smulson, 1989). 

The large number of critical variables in an enzymatic process makes its optimization cumbersome. However, many of the limitations of chemical synthesis can be overcome by protease synthesis. The high specificity and high reactivity under mild operation conditions, which is characteristic of enzymatic processes, can have a... 

Mutants of B. subtilis deficient in a-amylase and neutral protease synthesis sporulate normally thus removing these enzymes from category (i). However, serine protease deficient mutants that retained the ability to... 

Rupintrivir (72, Scheme 2.11) is a peptidomimetic protease inhibitor developed by Agouron Pharmaceuticals (San Diego, CA) for the treatment of human rhinovirus (HRV). A key component of the rupintrivir pharmacophore is the a,(3-unsaturated ester moiety, which acts as a Michael acceptor, forming a covalent bond with cysteine residues in the active site of HRV 3C protease. Synthesis of the 7-amino a,(3-unsaturated ester portion of rupintrivir involved coupling L-glutamic acid derivative 66 with 4-benzyloxazolidinone 67 via a mixed anhydride. Formation of the corresponding sodium enolate, followed by alkylation with allyl iodide 69, gave the a-allyl amide 70. 

Hanessian and Devasthale, 1996] Hanessian, S., and Devasthale, P. Design and synthesis of novel, pseudo C2 symmetric inhibitors of HIV protease. Bioorg. Med. Chem. Lett. 6 (1996) 2201-2206... 

Plasteins ate formed from soy protein hydrolysates with a variety of microbial proteases (149). Preferred conditions for hydrolysis and synthesis ate obtained with an enzyme-to-substrate ratio of 1 100, and a temperature of 37°C for 24—72 h. A substrate concentration of 30 wt %, 80% hydrolyzed, gives an 80% net yield of plastein from the synthesis reaction. However, these results ate based on a 1% protein solution used in the hydrolysis step this would be too low for an economical process (see Microbial transformations). 

Dica.rboxyIic AcidMonoesters. Enzymatic synthesis of monoesters of dicarboxyUc acids by hydrolysis of the corresponding diesters is a widely used and thoroughly studied reaction. It is catalyzed by a number of esterases. Upases, and proteases and is usually carried out in an aqueous buffer, pH 6—8 at room temperature. Organic cosolvents may be added to increase solubiUty of the substrates. The pH is maintained at a constant level by the addition of aqueous hydroxide. After one equivalent of base is consumed the monoesters are isolated by conventional means. 

FIGURE 16.28 HIV mRNA provides the genetic information for synthesis of a polyprotein. Proteolytic cleavage of this polyprotein by HIV protease produces the individnal proteins required for viral growth and cellular infection. 

The release of arachidonate and the synthesis or interconversion of eicosanoids can be initiated by a variety of stimuli, including histamine, hormones such as epinephrine and bradykinin, proteases such as thrombin, and even serum albumin. An important mechanism of arachidonate release and eicosanoid syn-... 

In the first publication describing the preparative use of an enzymatic reaction in ionic liquids, Erbeldinger et al. reported the use of the protease thermolysin for the synthesis of the dipeptide Z-aspartame (Entry 6) [34]. The reaction rates were comparable to those found in conventional organic solvents such as ethyl acetate. Additionally, the enzyme stability was increased in the ionic liquid. The ionic liquid was recycled several times after the removal of non-converted substrates by extraction with water and product precipitation. Recycling of the enzyme has not been reported. It should be noted, however, that according to the log P concept described in the previous section, ethyl acetate - with a value of 0.68 - may interfere with the pro-... 

The principal methods for the hydrolase-promoted synthesis of enantiomerically pure alcohols are depicted in Figure 6.44. Biocatalytic acylation and alcoholysis have been reviewed recently [116,117]. Lipases, esterases, and proteases catalyze these reactions, but CAL-B [118-120], CRL [121,122], and diverse lipase preparations from Pseudomonas species are common place. 

Biocatalysis has emerged as an important tool for the enantioselective synthesis of chiral pharmaceutical intermediates and several review articles have been published in recent years [133-137]. For example, quinuclidinol is a common pharmacophore of neuromodulators acting on muscarinic receptors (Figure 6.50). (JJ)-Quinudidin-3-ol was prepared via Aspergillus melleus protease-mediated enantioselective hydrolysis of the racemic butyrate [54,138]. Calcium hydroxide served as a scavenger of butyric acid to prevent enzyme inhibition and the unwanted (R) enantiomer was racemized over Raney Co under hydrogen for recycling. 

The cis P-lactams 57 are shown to act as cholesterol absorption inhibitors <96BMCL1947> and 58, an analogue of the dipeptide Phe-Gly methyl ester, is a protease inhibitor <96BMCL983>. A straightforward synthesis of proclavaminic acid 59, a biosynthetic precursor of clavulanic acid, is reported <96TA2277>. 

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