Mechanism-based inactivation of L-methionine. gamma. -lyase by L-2-amino-4-chloro-4-pentenoate

Journal Article · Tue Mar 07 04:00:00 EST 1989 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00431a022· OSTI ID:5719117

Esaki, Nobuyoshi; Takada, Harumi; Moriguchi, Mitsuaki; Hatanaka, Shinichi; Tanaka, Hidehiko; Soda, Kenji ^[1]

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1. Kyoto Univ. (Japan)

L-2-amino-4-chloro-4-pentenoic acid (L-ACP), an antibacterial amino acid produced by Amanita pseudoporphyria Hongo time dependently and irreversibly inactivates L-methionine {gamma}-lyase. The inactivation obeys biphasic pseudo-first-order kinetics and is carried out completely with a minimum molar ratio ((L-ACP)/(enzyme tetramer)) of 5. During the incubation of enzyme, 4.4-5.0 mol of chloride ions is formed per mole of tetramer enzyme. The tetrameric enzyme is labeled with 4 mol of DL-(2-{sup 14}C)ACP/mol. The authors have isolated {sup 14}C-labeled acetopyruvate and pyridoxamine 5'-phosphate from the ({sup 14}C)ACP-modified enzyme. The enzyme fully inactivated shows {lambda}{sub max} at 460 and 495 nm, which probably is derived from a conjugated pyridoximine parquinoid. The authors have proposed a mechanism which involves enzymatic dehalogenation from C{sub 4} of ACP to form a reactive allene. The allene is attacked by a nucleophilic amino acid residue at the active site. Analysis results of the thiol content of enzyme suggest that a cysteine residue is a possible nucleophilic residue covalently bound to the inactivator.

• OSTI ID: 5719117
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 28:5; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
BACTERIA
BIOCHEMICAL REACTION KINETICS
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
ENZYMES
GROWTH
INACTIVATION
KINETICS
LABELLED COMPOUNDS
LYASES
MICROORGANISMS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
REACTION KINETICS
VALERIC ACID