Transaminases ketoglutarate transaminase

ANALYTICALTffiTHODS - HYPHENATED INSTRUTffiNTS] (Vol 2) Leucine a-ketoglutarate transaminase... 

Alcohol dehydrogenase (5) and leucine a-ketoglutarate transaminase (33,34) contribute to the development of aroma during black tea manufacturing. Polyphenol oxidase and peroxidase are essential to the formation of polyphenols unique to fermented teas. 

Schousboe, A., Wu, J. Y., and Roberts, E. (1973) Purification and characterization of the 4-aminobutyrate-2,ketoglutarate transaminase from mouse brain. Biochemistry 12,2868-2873. 

Jaeger et al. (1975) found that chloroprene is markedly more hepatotoxic to fasted adult male Holtzman rats (250-350 g bw) than to rats fed ad libitum, following inhalation exposure to 500, 1000 or 2000 ppm [1810, 3620 or 7240 mg/m ] chloroprene. These concentrations produced increases in serum alanine a-ketoglutarate transaminase activity and caused death in the fasted rats, while producing no effect in the fed rats. At 10 000 ppm [36 200 mg/m ], the fed-fasted difference following chloroprene exposure disappeared. 

Thompson EB, Tomkins GM, Curran JF. 1966. Induction of tyrosine alpha-ketoglutarate transaminase by steroid hormones in a newly established tissue culture cell line. Proc. Natl. Acad. Sci. USA 56 296-303... 

L-Phosphinothricin, the active ingredient of the broad-spectrum herbicide Basta (AgrEvo), can be obtained through enzymatic transamination of the corresponding oxoacid, 2-oxo-4-[(hydroxy)(methyl)phosphinoyl]butyric acid, in a coupled system with aspartate aminotransferase (AAT) and 4-aminobutyrate 2-ketoglutarate transaminase (E.C. 2.6.1.19) from E. coli (Fig. 12.7-6)[37 . In solutions containing 10% substrate, 85 % conversion was reached with only < 3 % amino acid by-products. For... 

Fig. 5. Changes of liver enzyme activities after tyrosine dosage of guinea pigs tyrosine-a-ketoglutarate transaminase (- -o- -), p-hydroxyphenylpyruvate oxidase (— x—). Each point is the average of homogenates from two animals. From Knox and Goswami (Kll).

The most useful, and thus far successful, examples have involved irreversible reactions of nucleophilic functions of an enzyme s reactive site with an enzymatically activated Kcat inhibitor of a Michael-type addition reaction. The activation invariably requires participation of the enzyme s prosthetic group (e.g., flavin of monoamine oxidase) or coenzymes such as pyridoxal (vitamin B) as its phosphate, which is associated with several enzymes (e.g., threonine dehydrase, ornithine decarboxylase, a-ketoglutarate transaminase). 

The usual degradative enzyme for GABA, a GABA a-ketoglutarate transaminase, has been identified in C. elegans (153) and Nippostrongylus brasiliensis (154). 

GABA-T GABA ketoglutarate transaminase PMDD Premenstrual dysphoric disorder... 

Sereni F, Kenny FT, Kretchmer N. Factors influencing the development of tyrosine-a-ketoglutarate transaminase activity in rat liver. J Biol Chem 1959 234 609-612. 

Jung MJ, Metcalf BW. Catalytic inhibition of gamma-aminobutyric acid - alpha-ketoglutarate transaminase of bacterial origin by 4-aminohex-5-ynoic acid, a substrate analog. Biochem Biophys Res Commun 1975 67 301-306. 

Saito K, Barber R, Wu J -Y, Matsuda T, Roberts E and Vaughn J E (1974a) Immunohistochemical localization of glutamic acid decarboxylase in rat cerebellum Proc Natl. Acad Sci USA 71, 269-273 Saito K., Schousboe A, Wu J.-Y, and Roberts E (1974b) Some immunochemical properties and species specificity of GABA-a-ketoglutarate transaminase from mouse brain Brain Res 65, 287-296. 

Dann O. T. and Carter T. E. (1964) Cycloserine inhibition of gamma-ammo butync-alpha-ketoglutaric transaminase. Biochem Pharmacol 13, 677-684. 

Wicks, W. D. 1968. Tyrosine-a-ketoglutarate transaminase Induction by epinephrine and adenosine 3 , 5 cyclic phosphate. Science, 160 997. 

This molecule specifically and irreversibly inhibits y-aminobutyrate-a-ketoglutarate transaminase. The Ki for this molecule is 2.8 ixM, some three orders of magnitude lower than the Km for the natural substrate, y-aminobutyrate. The ti/2 for inactivation of the bacterial enzyme is 9 min at 0.3 fuM gabaculine. As expected, gabaculine is not an irreversible inhibitor of the enzyme in the pyridoxamine form, and the mechanism of the irreversible inhibition by gabaculine is completely in accord with the hypothesis that enzymic conversion before inhibition. The possible mechanisms proposed for the inhibition are those in Eq. (5). ... 

Aminobutyrate-a-ketoglutarate transaminase (GABA transaminase), 33 7-Aminobutyric acid, 33,163 n-3-Amino-3-carboxypropane sulfonamide, 415, 419... 

Gabaculine, see l,3-Cyclohexadienyl-5-aminocarboxylic acid GABA transaminase, see v-Aminobuty-rate-a-ketoglutarate transaminase D-Galaotal, 26... 

Injection of hydrocortisone into the rat results in an approximately four fold increase in liver (but not kidney) tyrosine-a-ketoglutarate transaminase activity 374)- Corticosterone and cortisone were somewhat less effective. Interesting in this connection is the observation that injection of L-tyrosine increased the activity of tyrosine-a-ketoglutarate transaminase to about the same extent as hydrocortisone. Other amino acids had a much smaller stimulating effect which was attributed to adrenal cortical stress. In a preliminary report the addition of hydrocortisone to lymphocyte suspensions was found to inhibit glutamic-oxalacetic transaminase activity 376). 

Kenney ( 09) also has considerably purified a tyrosine-a-ketoglutarate transaminase from rat liver. Its properties are quite similar to those of the dog liver enzyme. 

Tjo osine-a-ketoglutarate transaminase (210) is an inducible enzyme much like tryptophan pyrrolase (see Section XIII). The ability to increase the transaminase activity in liver by tyrosine administration depends on the integrity of adrenal cortical function. 

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