Interaction of Cu,Zn Superoxide Dismutase with Hydrogen Sulfide
Addition of HS − enhanced the O − 2scavenging activity of bovine erythrocyte Cu,Zn superoxide dismutase (EC 1.15.1.1) by about twofold. The positive effect was measured using a diverse selection of SOD activity assays, and cannot be an artifact restricted to any single technique. K m values for HS −...
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Published in | Archives of biochemistry and biophysics Vol. 318; no. 2; pp. 251 - 263 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
United States
Elsevier Inc
20.04.1995
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Subjects | |
Online Access | Get full text |
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Summary: | Addition of HS
− enhanced the O
−
2scavenging activity of bovine erythrocyte Cu,Zn superoxide dismutase (EC 1.15.1.1) by about twofold. The positive effect was measured using a diverse selection of SOD activity assays, and cannot be an artifact restricted to any single technique.
K
m values for HS
− varied in different assay techniques, but we estimate
K
m ≍ 80 μM HS
−. In contrast to HS
−, other small molecules tested with SOD either had little effect or were inhibitory. Consumption of HS
− and O
−
2 occurred in nearly 1:1 mole ratio. The products were H
2O
2 and sulfane sulfur, such as either elemental sulfur or polysulfide. Binding of HS
− to the enzyme was rapid, with
k > 10
7 M
−1 s
−1. The resulting complex exhibited a Cu-to-S charge-transfer absorbance band at 345 nm and an altered Cu(II) EPR spectrum. Taken together, these observations suggest that HS
− binds at the catalytic Cu center of SOD and can be a genuine substrate of the enzyme. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0003-9861 1096-0384 |
DOI: | 10.1006/abbi.1995.1228 |