Kinetic properties of light-dependent ascorbic acid oxidation by melanin

Randolph D. Glickman, Raymond Sowell, Kwok Wai Lam

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

The kinetic properties of ascorbic acid oxidation by light-activated melanin granules demonstrate the presence of a specific reactive site on the melanin granule saturable by ascorbic acid. Increased light intensity increased the Vmax and reduced the Km of this reaction, indicating increased affinity of the active site for ascorbic acid. The kinetics of this reaction are not markedly changed in a reduced-oxygen environment. Ascorbic acid oxidation is competitively inhibited by isoascorbic acid, an epimer of ascorbic acid, while other tested reducing agents are inactive. The Ki for isoascorbic acid is 1 mM, about the same as the Km of ascorbic acid.

Original languageEnglish (US)
Pages (from-to)453-457
Number of pages5
JournalFree Radical Biology and Medicine
Volume15
Issue number4
DOIs
StatePublished - 1993

Fingerprint

Melanins
Ascorbic Acid
Light
Oxidation
Kinetics
Catalytic Domain
Reducing Agents
Oxygen

Keywords

  • Ascorbic acid
  • Free radicals
  • Isoascorbic acid
  • Kinetics
  • Light
  • Melanin

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Medicine(all)
  • Toxicology

Cite this

Kinetic properties of light-dependent ascorbic acid oxidation by melanin. / Glickman, Randolph D.; Sowell, Raymond; Lam, Kwok Wai.

In: Free Radical Biology and Medicine, Vol. 15, No. 4, 1993, p. 453-457.

Research output: Contribution to journalArticle

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