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 language | English (US) |
|---|---|
| Pages (from-to) | 453-457 |
| Number of pages | 5 |
| Journal | Free Radical Biology and Medicine |
| Volume | 15 |
| Issue number | 4 |
| DOIs | |
| State | Published - 1993 |
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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 journal › Article
}
TY - JOUR
T1 - Kinetic properties of light-dependent ascorbic acid oxidation by melanin
AU - Glickman, Randolph D.
AU - Sowell, Raymond
AU - Lam, Kwok Wai
PY - 1993
Y1 - 1993
N2 - 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.
AB - 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.
KW - Ascorbic acid
KW - Free radicals
KW - Isoascorbic acid
KW - Kinetics
KW - Light
KW - Melanin
UR - http://www.scopus.com/inward/record.url?scp=0027358395&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0027358395&partnerID=8YFLogxK
U2 - 10.1016/0891-5849(93)90045-V
DO - 10.1016/0891-5849(93)90045-V
M3 - Article
C2 - 8225027
AN - SCOPUS:0027358395
VL - 15
SP - 453
EP - 457
JO - Free Radical Biology and Medicine
JF - Free Radical Biology and Medicine
SN - 0891-5849
IS - 4
ER -