Enzymatic Inhibitor

L. W. Parker, and J. J. Venit, Biocatalytic preparation of a chiral synthon for a vasopeptidase inhibitor enzymatic conversion of N2-[N-phenylmethoxy)carbo-nyl] L-homocysteinyl]- l-lysine (1,1 J-disulfide to 4S-(4/,71,10aJ)]-l-octahydro-5-oxo-4-[phenylmethoxy)carbonyl]amino]-7H-pyrido-[2,l-b][l,3]thiazepine-7-carboxylic add methyl ester by a novel l -lysine e-aminotransferase, Enzyme Microb. Technd. 2000, 27, 376-389. 

Figure 1 Preparation of chiral synthon for vasopeptidase inhibitor enzymatic synthesis of L-6-hydroxynorleucine (1) using glutamate dehydrogenase.

FIGURE 16.15 Tryptase inhibitors . Enzymatic preparation of (S )-A -(tert-butoxycarbonyl)-3-hydroxymethyl piperidine 56. 

Patel RN, Banerjee A, Pendri YR, et al. Preparation of a chiral synthon for an HBV inhibitor enzymatic asymmetric hydrolysis of (la,2p,3a)-2-(benzyloxymethyl)cyclo-pent-4-ene-l,3-diol diacetate and enzymatic asymmetric acetylation of (la,2p,3a)-2-(benzyloxymethyl)cyclopent-4-ene-l,3-diol. Tetrahedron Asymmetry 17(2), 175, 2006. 

Patel. R.N.. Banerjee.A., Nanduri, V., Goldberg. S.. Johnston. R.. Hanson, R., McNamee, C., Brzozowski. D.. Tully. T.. Ko. R.. LaPorte. T.. Cazzulino, D., Swaminathan, S.. Parker. L.. and Venit. J. (2000) Biocatalytic Preparation of a Chiral Synthon for a Vasopeptidase Inhibitor Enzymatic Conversion of bP- N-[(Phenylmethoxy)carbonyl]L-homocysteinyl]-L-lysine (1>1 )-disulfide to [4B-(4a.7a,10ab)]l-Octahydro-5-oxo-4-[(phenyl-methoxy) carbonyl]amino]-7H-pyrido-[2.1-b][l 3]thiazepin-7-carboxylic Acid Methyl Ester by a Novel S-Lysine a-Amino-transferase. Enzyme Microb. Technol. 27,376-389. 

ENZYMATIC ACYLATION 4.1 Farnesyl Transferase Inhibitor Enzymatic Resolution of Substituted (6,U-Dihydro-5H-benzo-[5,6]cyclohepta[l,2-p]pyridin-U-yl)piperidines)... 

Farnesyl transferase inhibitor enzymatic resoiution of substituted (6,11-dihydro-5H-benzo-[5,6]cyciohepta[1,2-p]pyridin-11-yi)piperidines. 

Rhinovirus protease inhibitor enzymatic preparation of (A)-3-(4-fluorophenyl)-2-hydroxy propionic acid. 

Thrombin inhibitor enzymatic synthesis of (A)-2-Hydroxy-3,3-dimethyibutanoic acid. 

GAMMA SECRETASE INHIBITOR ENZYMATIC SYNTHESIS OF (R) 5,5,5-TRIFLUORONORVALINE... 

Peng, Z. Wong, J. W. Hansen, E. C. Puchlopek-Dermenci,A. L. Clarke,H.J., Development of a concise, asymmetric synthesis of a smoofhened receptor (SMO) inhibitor Enzymatic transamination of a 4-piperidinone with d5mamic kinetic resolution. Organic Letters 2014, 16(3), 860-863. 

Certain factors and product precursors are occasionally added to various fermentation media to iacrease product formation rates, the amount of product formed, or the type of product formed. Examples iaclude the addition of cobalt salts ia the vitamin fermentation, and phenylacetic acid and phenoxyacetic acid for the penicillin G (hen ylpenicillin) and penicillin V (phenoxymethylpenicillin) fermentations, respectively. Biotin is often added to the citric acid fermentation to enhance productivity and the addition of P-ionone vastly iacreases beta-carotene fermentation yields. Also, iaducers play an important role ia some enzyme production fermentations, and specific metaboHc inhibitors often block certain enzymatic steps that result in product accumulation. 

Another class of therapeutic agents is used for the treatment of certain genetic diseases or other enzymatic disorders caused by the dysfunction or absence of one particular enzyme. This often leads to an unwanted accumulation or imbalance of metaboUtes in the organism. Eor example, some anticonvulsive agents are inhibitors for y-aminobutyric acid aminotransferase [9037-67-6]. An imbalance of two neurotransmitters, glutamate and y-aminobutyric acid, is responsible for the symptoms. Inhibition of the enzyme leads to an increase of its substrate y-aminobutyric acid, decreasing the imbalance and subsequently relieving the symptoms of the disease. 

Cychc alcohols are excellent targets for enantioselective enzymatic acylations. For example, acylation of (65) with vinyl acetate catalyzed by Hpase SAM-II gives the (R),(3)-ester with 95% ee (81). Similarly (66), which is a precursor for seratonin uptake inhibitor, is resolved in a high yield and selectivity with Amano Hpase P (82). The prostaglandin synthon (67) is resolved by the same method into the optically pure alcohol in 35% yield (83). 

An enzymatic assay can also be used for detecting anatoxin-a(s). " This toxin inhibits acetylcholinesterase, which can be measured by a colorimetric reaction, i.e. reaction of the acetyl group, liberated enzymatically from acetylcholine, with dithiobisnitrobenzoic acid. The assay is performed in microtitre plates, and the presence of toxin detected by a reduction in absorbance at 410 nm when read in a plate reader in kinetic mode over a 5 minute period. The assay is not specific for anatoxin-a(s) since it responds to other acetylcholinesterase inhibitors, e.g. organophosphoriis pesticides, and would need to be followed by confirmatory tests for the cyanobacterial toxin. 

Protein engineering is now routinely used to modify protein molecules either via site-directed mutagenesis or by combinatorial methods. Factors that are Important for the stability of proteins have been studied, such as stabilization of a helices and reducing the number of conformations in the unfolded state. Combinatorial methods produce a large number of random mutants from which those with the desired properties are selected in vitro using phage display. Specific enzyme inhibitors, increased enzymatic activity and agonists of receptor molecules are examples of successful use of this method. 

The three most common types of inhibitors in enzymatic reactions are competitive, non-competitive, and uncompetitive. Competitive inliibition occurs when tlie substrate and inhibitor have similar molecules that compete for the identical site on the enzyme. Non-competitive inhibition results in enzymes containing at least two different types of sites. The inhibitor attaches to only one type of site and the substrate only to the other. Uncompetitive inhibition occurs when the inhibitor deactivates the enzyme substrate complex. The effect of an inhibitor is determined by measuring the enzyme velocity at various... 

Kinetics is the branch of science concerned with the rates of chemical reactions. The study of enzyme kinetics addresses the biological roles of enzymatic catalysts and how they accomplish their remarkable feats. In enzyme kinetics, we seek to determine the maximum reaction velocity that the enzyme can attain and its binding affinities for substrates and inhibitors. Coupled with studies on the structure and chemistry of the enzyme, analysis of the enzymatic rate under different reaction conditions yields insights regarding the enzyme s mechanism of catalytic action. Such information is essential to an overall understanding of metabolism. 

It is revealing to compare the equation for the uninhibited case. Equation (14.23) (the Michaelis-Menten equation) with Equation (14.43) for the rate of the enzymatic reaction in the presence of a fixed concentration of the competitive inhibitor, [I]... 

If the inhibitor combines irreversibly with the enzyme—for example, by covalent attachment—the kinetic pattern seen is like that of noncompetitive inhibition, because the net effect is a loss of active enzyme. Usually, this type of inhibition can be distinguished from the noncompetitive, reversible inhibition case since the reaction of I with E (and/or ES) is not instantaneous. Instead, there is a time-dependent decrease in enzymatic activity as E + I El proceeds, and the rate of this inactivation can be followed. Also, unlike reversible inhibitions, dilution or dialysis of the enzyme inhibitor solution does not dissociate the El complex and restore enzyme activity. 

Cheng, Y. C., andPrasoff, W. H. (1973). Relationship between the inhibition constant (Ki) and the concentration of inhibitor which causes 50 percent inhibition (150) of an enzymatic reaction. Biochem. Pharmacol. 22 3099—3108. 

In die metabolic pathway to an amino add several steps are involved. Each step is die result of an enzymatic activity. The key enzymatic activity (usually die first enzyme in the synthesis) is regulated by one of its products (usually die end product, eg die amino add). If die concentration of die amino add is too high die enzymatic activity is decreased by interaction of die inhibitor with the regulatory site of die enzyme (allosteric enzyme). This phenomenon is called feedback inhibition. 

Nonvolatile Inhibitors. Glycosides A number of toxic constituents are known to be released by the enzymatic degradation of various glycosides. Some of the volatile components have been mentioned previously—i.e., isothiocyanates from mustard oil glycosides and hydrogen cyanide from cyanogenic glycosides. 

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