Ct-Ketoglutarate

Most amino acids lose their nitrogen atom by a transamination reaction in which the -NH2 group of the amino acid changes places with the keto group of ct-ketoglutarate. The products are a new a-keto acid plus glutamate. The overall process occurs in two parts, is catalyzed by aminotransferase enzymes, and involves participation of the coenzyme pyridoxal phosphate (PLP), a derivative of pyridoxine (vitamin UJ. Different aminotransferases differ in their specificity for amino acids, but the mechanism remains the same. 

These also are direct capture agents for CN. The CN ion reacts with carbonyl groups to form cyanohydrins, resulting in a sequestering action. Among cyanohydrin formers, ct-ketoglutaric acid has shown some promise experimentally as a CN antidote (Hume et al, 1995 Moore et al., 1986), and there is a possible additional antidotal activity by causing a decrease in convulsions (Yamamoto, 1990). 

See also Glyoxylate Cycle, Aconitase, Citrate, Isocitrate Dehydrogenase, ct-Ketoglutarate, Fluorocitrate, Citric Acid Cycle Intermediates, Figure 14.3, Table 14.1... 

Vaillancourt FH, Yin J, Walsh CT (2005) SyrB2 in Syringomycin E Biosynthesis is a Nonheme Fen a-Ketoglutarate- and 02-Dependent Halogenase. Proc Natl Acad Sci USA 102 10111... 

Figure 2.4. The provision of acetyl-CoA and NADPH for lipogenesis. PPP, pentose phosphate pathway T, tricarboxylate transporter K, a-ketoglutarate transporter. In ruminants, pyruvate dehydrogenase, ATP-citrate lyase and malic enzyme activities are low and perhaps non-functional. (From Murray et al., 1988. Harper s Biochemistry, 21st edn, p. 207, Appleton and Lange, Norwalk, CT reproduced with permission of The McGraw-Hill Companies).

M7. Marshall, L. M., and Drew, F. D., Determination of fumaric, cts-aconitic and a-ketoglutaric acids in rabbit kidney and liver by partition chromatography. Federation Proc. 9, 199 (1950). 

Isotopic C marked with asterisk. All the isotope appears in the a-carboxyl of o-ketoglutaric acid if the side reaction between citric and m-aconitic acids is neglected. The side reaction, as shown in Scheme 4, would produce a second isotopic form of cts-aconitic acid but its quantities would be small if the side reaction is slow.)... 

Vaillancourt FH, Yin J, Walsh CT. SyrB2 in syringomycin E biosynthesis is a nonheme Fe-11 alpha-ketoglutarate- and 02-dependent halogenase. Proc. Nat. Acad. Sci. USA 2005 102 10111-10116. 

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