Reductive trapping of substrate to bovine plasma amine oxidase

Journal Article · Sun Jan 25 00:00:00 EST 1987 · J. Biol. Chem.; (United States)

OSTI ID:6934851

Hartmann, C; Klinman, J P

Plasma amine oxidases catalyze the oxidative deamination of amines to aldehydes, followed by a 2e- reduction of O/sub 2/ to H/sub 2/O/sub 2/. Pyrroloquinoline quinone (PQQ), previously believed to be restricted to prokaryotes, has recently been proposed to be the cofactor undergoing reduction in the first half-reaction of bovine plasma amine oxidase (Ameyama, M., Hayashi, U., Matsushita, K., Shinagawa, E., and Adachi, O. (1984) Agric. Biol. Chem. 48, 561-565; Lobenstein-Verbeek, C. L., Jongejan, J. A., Frank, J., and Duine, J. A. (1984) FEBS Lett. 170, 305-309). This result is unexpected, since model studies with PQQ implicate Schiff's base formation between a reactive carbonyl and substrates, whereas experiments with bovine plasma amine oxidase have failed to provide evidence for a carbonyl cofactor. We have, therefore, re-examined putative adducts between substrate and enzyme-bound cofactor, employing a combination of (/sup 14/C)benzylamine and (/sup 3/H)NaCNBH/sub 3/. The use of the relatively weak reductant, NaCNBH/sub 3/, affords Schiff's base specificity and permits the study of enzyme below pH 7.0. As we show, enzyme can only be inactivated by NaCNBH/sub 3/ in the presence of substrate, leading to the incorporation of 1 mol of (/sup 14/C)benzylamine/mol of enzyme subunit at complete inactivation. By contrast, we are unable to detect any labeling with (/sup 3/H)NaCNBH/sub 3/, analogous to an earlier study with (/sup 3/H)NaCNBH/sub 4/ (Suva, R. H., and Abeles, R. H. (1978) Biochemistry 17, 3538-3545). We conclude, first, that our inability to obtain adducts containing both carbon 14 and tritium rules out the reductive trapping either of amine substrate with pyridoxal phosphate or of aldehyde product with a lysyl side chain and, second, that the observed pattern of labeling is fully consistent with the presence of PQQ at the active site of bovine plasma amine oxidase.

• Research Organization: Univ. of California, Berkeley
• OSTI ID: 6934851
• Journal Information: J. Biol. Chem.; (United States), Vol. 3
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
59 BASIC BIOLOGICAL SCIENCES
AMINES
METABOLISM
OXIDOREDUCTASES
ENZYME ACTIVITY
ALDEHYDES
BIOCHEMISTRY
BLOOD PLASMA
BOROHYDRIDES
CARBON 14 COMPOUNDS
CATTLE
DEAMINATION
HYDROGEN PEROXIDE
QUINOLINES
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ANIMALS
AROMATICS
AZAARENES
AZINES
BIOLOGICAL MATERIALS
BLOOD
BODY FLUIDS
BORON COMPOUNDS
CHEMICAL REACTIONS
CHEMISTRY
DOMESTIC ANIMALS
ENZYMES
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
MATERIALS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PEROXIDES
PYRIDINES
RUMINANTS
VERTEBRATES
560300* - Chemicals Metabolism & Toxicology
550501 - Metabolism- Tracer Techniques