The inactivation of ornithine aminotransferase by an enzyme-activated irreversible inhibitor 4-aminohex-5-ynoate was accompanied by stoichiometric binding of the radiolabeled compound. Distribution of radiolabel among separated tryptic peptides indicated that more than one amino acid residue had reacted. Lys-292 and Cys-388 were positively identified. Reduction with borohydride was necessary to stabilize the adduct formed with Lys-292, and the relevant peptide prepared after this treatment contained equimolar amounts of inhibitor and coenzyme. The coenzyme chromophore in this peptide showed strong negative circular dichroism. A mechanism consistent with these observations is proposed.
MECHANISM OF INACTIVATION AND IDENTIFICATION OF SITES OF MODIFICATION OF ORNITHINE AMINOTRANSFERASE BY 4-AMINOHEX-5-YNOATE / DE BIASE, Daniela; Simmaco, Maurizio; Barra, Donatella; Bossa, Francesco; Michael, Hewlins; John, Ra. - In: BIOCHEMISTRY. - ISSN 0006-2960. - STAMPA. - 30:8(1991), pp. 2239-2246. [10.1021/bi00222a029]
MECHANISM OF INACTIVATION AND IDENTIFICATION OF SITES OF MODIFICATION OF ORNITHINE AMINOTRANSFERASE BY 4-AMINOHEX-5-YNOATE
DE BIASE, Daniela;SIMMACO, Maurizio;BARRA, Donatella;BOSSA, Francesco;
1991
Abstract
The inactivation of ornithine aminotransferase by an enzyme-activated irreversible inhibitor 4-aminohex-5-ynoate was accompanied by stoichiometric binding of the radiolabeled compound. Distribution of radiolabel among separated tryptic peptides indicated that more than one amino acid residue had reacted. Lys-292 and Cys-388 were positively identified. Reduction with borohydride was necessary to stabilize the adduct formed with Lys-292, and the relevant peptide prepared after this treatment contained equimolar amounts of inhibitor and coenzyme. The coenzyme chromophore in this peptide showed strong negative circular dichroism. A mechanism consistent with these observations is proposed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
