Transaminases enzymes

Figure 3 A mimic of the enzyme transaminase achieves high stereoselectivity in the product amino acid because of geometric control by the attached basic chain.

A modified cyclodextrin (25), which contains a pyridoxamine moiety, catalyzes the transamination as shown in Scheme 8 [39]. The reaction between (25) and indolepyruvic acid (26) is 200 times faster than the reaction between pyridoxamine and (26), since the first reaction is an intracomplex one and the second is an intermolecular one. Transamination is completed by the reaction of (27), formed by the reaction between (25) and (26), with another amino acid, regenerating (25). Thus (25) which consists of a cyclodextrin and a pyridoxamine is a model of the enzyme transaminase. 

Effects of 3- and i4.-mercapto-2-amino acids. It has long been known that 1,2- and 1,3-aminothiols, and especially the substrate-like mercapto-amino acids - penicillamine, homocysteine et al. - strongly inhibit many PLP-enzymes(transaminases, c<-decarboxylases, y cystathionase, and others) by condensing with the carbonyl group of PLP in the active site to stable heterocyclic compounds (thiazolidines, resp., thiazanes), see Pefs. 5 ... 

One class of enzymes that follow a ping-pong-type mechanism are aminotransferases (previously known as transaminases). These enzymes catalyze the transfer of an amino group from an amino acid to an a-keto acid. The products are a new amino acid and the keto acid corresponding to the carbon skeleton of the amino donor ... 

When administering tacrine, the nurse must monitor the patient for liver damage. This is best accomplished by monitoring alanine aminotransferase (AIT) levels. ALT is an enzyme found predominately in the liver. Disease or injury to the liver causes a release of tiiis enzyme into the bloodstream, resulting in elevated ALT levels, hi patients taking tacrine, ALT levels should be obtained weekly from at least week 4 to week 16 after die initiation of tiierapy. After week 16, transaminase levels are monitored every 3 months. 

I 2 Directed Evolution as a Means to Engineer Enantioseleaive Enzymes (S)-transaminase... 

The enzymes found in liver cells (Group I enzymes) include more than a dozen enzymes used in diagnostic laboratories, but those used most commonly are the transaminases (GOT and GPT), which continue to be the most widely used indicators of liver cell integrity. Enzymes found in the biliary cells (Group II) include alkaline phosphatase, glutamyl-transferase, leucine amniopeptidase and 3-nucleotidase. 

Russell, C. D. Cotlove, E. Serum glutamic-oxaloacetic transaminase Evaluation of a coupled-reaction enzyme assay by means of kinetic theory. Clin. Chem. (1971), 17, 1114-1122. 

GABA transaminase is a mitochondrial enzyme which, like GAD, requires pyridoxal phosphate as co-factor. It is present in both neurons and glia and while secondary to... 

Transaminases Hepatocellular enzymes that are released into the bloodstream after hepatic damage. 

AOPP and AOA inhibit transaminase enzymes (39, 44) and other pyridoxylphosphate-dependent enzymes, presumably by interference with the carbonyl group of pyridoxyl phosphate (45). They apparently inhibit PAL by interaction with the carbonyl-like group involved in catalysis by PAL (36). AOA is not an effective PAL inhibitor for in vivo studies because of its lack of specificity that results in a relatively high degree of phytotoxicity (e.g. 

The high toxicity of AOA is due to its very high efficiency as a transaminase inhibitor (K =0.45 pM) as compared to its efficacy as a PAL inhibitor (K. = 120 pM) (48), making it impossible to effectively inhibit PAL iti vivo without also greatly inhibiting amino acid metabolism. Other pyridoxyl phosphate-requiring enzymes, such as ACC synthase (an enzyme involved in ethylene production) (49), are also more sensitive to AOA than to AOPP. 

Hwang, B.-Y. and Kim, B.-G. (2004) High-throughput screening method for the identification of active and enantioselective m-transaminases. Enzyme and Microbial Technology, 34, 429-436. 

There is a further possibility for conversion of methionine to MT. Transaminase enzymes can convert methionine to 4-methylthio-2-oxobutanoate (also, a-keto-y-methylthiobutyrate). One such enzyme is aromatic-amino-acid transaminase, EC 2.6.1.57, for which L-methionine is, albeit, less efficiently, a substrate (Equation 5) ... 

Increased serum glutamic oxaloacetic transaminase enzyme activity Increased blood pressure increased hemoglobin... 

Ketoconazole inhibits a variety of cytochrome P450 enzymes, including 11-hydroxylase and 17-hydroxylase. It is highly effective in lowering cortisol in Cushing s disease, and patients can be maintained successfully on therapy for months to years. The most common adverse effects are reversible elevation of hepatic transaminases and GI upset. It can cause gynecomastia and lower plasma testosterone values. 

The aminotransferases, aspartate transaminase and alanine transaminase, are enzymes that have increased concentrations in plasma following hepatocellular injury. The highest concentrations are seen in acute viral infections, or ischemic or toxic liver injury. 

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