Proposed mechanisms for HOOOH formation in two typical enzyme reactions responsible for superoxide anion production in biological systems

Masahiro Kohno, Emiko Sato, Noriko Yaekashiwa, Takayuki Mokudai, Yoshimi Niwano

Research output: Contribution to journalReview article

6 Citations (Scopus)

Abstract

We investigated the hypoxanthine (HPX)-xanthine oxidase (XOD) reaction by examining the chemiluminescence (CL) response mediated by a luminol analog, 8-amino-5-chloro-7-phen-y]pyrido[3,4-d]pyridazine-1,4-(2H, 3H)-dione sodium salt (1-012). It was found that addition of a high concentration of dimethyl sulfoxide (DMSO), a potent OH scavenger, could not completely reduce the CL response. This result suggests the existence of an unknown reactive oxygen intermediate other than O 2 - and OH. We further examined the HPX-XOD reaction and the nicotinamide adenine dinucleotide phosphate (NADPH) oxidation reaction by applying an electron spin resonance (ESR) spin-trapping method. In both reaction systems, similar responses were observed. That is, addition of DMSO increased the formation of 5,5-dimethyl-l-pyrroline N-oxide (DMPO) -OOH in a concentration-dependent manner. This indicates that scavenging of OH increases the detected O 2 - level, further suggesting the existence of an intermediate oxygen species derived from O 2 - and OH. One candidate for this species is HOOOH, presumably formed in the following way.

Original languageEnglish
Pages (from-to)302-307
Number of pages6
JournalChemistry Letters
Volume38
Issue number4
DOIs
Publication statusPublished - 2009 Jul 20

ASJC Scopus subject areas

  • Chemistry(all)

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