Labeling of the active site of cytoplasmic aspartate aminotransferase by β-chloro-L-alanine

Citations of this article
Mendeley users who have this article in their library.
Get full text


Syncatalytic inactivation of pig heart cytoplasmic aspartate aminotransferase by β-chloro-[U-14C]L-alanine resulted in the incorporation of radioactivity corresponding to one mole of the label per mole of the monomeric unit of the enzyme. A borohydride-reduced and then carboxymethylated preparation of the labeled enzyme was digested by trypsin. A radioactive peptide was isolated and found to contain a covalently linked pyridoxyl derivative which absorbed at 325 nm. The amino acid sequence of this peptide was Tyr-Phe-Val-Ser-Glu-Gly-Phe -Glu-Leu-Phe-Cys-Ala-Gln-Ser-Phe-Ser-Lys{black star}-Asn-Phe-Gly-Leu-Tyr-Asn-Glu-Arg. In the peptide the phosphopyridoxyl group seems to be covalently bound via alanyl moiety derived from β-chloro-L-alanine, the β-carbon atom of which is covalently linked to the ε{lunate}-nitrogen atom of the lysyl residue(Lys{black star}). From a comparison with the amino acid composition of the phosphopyridoxyl peptide isolated from the tryptic digest of a borohydride-reduced holoenzyme, it was concluded that the modified lysul residue was identical to that involved in binding pyridoxal phosphate to the apoenzyme. © 1973.




Morino, Y., & Okamoto, M. (1973). Labeling of the active site of cytoplasmic aspartate aminotransferase by β-chloro-L-alanine. Biochemical and Biophysical Research Communications, 50(4), 1061–1067.

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free