Solvent exchangeable protons and the activation of molecular oxygen: the galactose oxidase reaction

Journal Article · Fri Jan 01 00:00:00 EST 1988 · Prog. Clin. Biol. Res.; (United States)

OSTI ID:6765283

Kosman, D J; Driscoll, J J

The reduction of O/sub 2/ to H/sub 2/O/sub 2/ requires two protons as well as two electrons. Thus, activation of dioxygen reasonably may involve either general or specific acid catalysis. Consequently, the reduction of O/sub 2/ to H/sub 2/O/sub 2/ could exhibit a kinetic solvent isotope effect (KSIE). The reaction catalyzed by the mononuclear Cu(II) enzyme, galactose oxidase does exhibit a KSIE (+1.55). The pL-rate profile exhibits an alkaline shift in D/sub 2/O which can be attributed to the differential partitioning of H+ versus D+ between bulk water and a metal-bound H/sub 2/O (delta pKa = +0.19). A variety of spectral evidence places an equatorial, Cu(II)-liganded water molecule at the active site of galactose oxidase. The analysis of the KSIE data is detailed and the potential generality of the function of such metal-bound H/sub 2/O at other type 2 Cu(II) sites is discussed.

• Research Organization: State Univ. of New York, Buffalo (USA)
• OSTI ID: 6765283
• Journal Information: Prog. Clin. Biol. Res.; (United States), Vol. 274
• 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
HYDROGEN PEROXIDE
BIOSYNTHESIS
OXIDOREDUCTASES
BIOCHEMICAL REACTION KINETICS
OXYGEN
REDOX REACTIONS
DEUTERIUM
ELECTRONS
ISOTOPE EFFECTS
PROTONS
SOLVENTS
TRACER TECHNIQUES
BARYONS
CHEMICAL REACTIONS
ELEMENTARY PARTICLES
ELEMENTS
ENZYMES
FERMIONS
HADRONS
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LEPTONS
LIGHT NUCLEI
NONMETALS
NUCLEI
NUCLEONS
ODD-ODD NUCLEI
OXYGEN COMPOUNDS
PEROXIDES
REACTION KINETICS
STABLE ISOTOPES
SYNTHESIS
560300* - Chemicals Metabolism & Toxicology
550201 - Biochemistry- Tracer Techniques