PMID: 6108132Nov 6, 1980Paper

Oxidative modulation of soluble guanylate cyclase by manganese

Biochimica Et Biophysica Acta
J M Braughler

Abstract

Homogeneous or partially purified soluble guanylate cyclase (GTP pyrophosphate-lyase (cyclizing), EC 4.6.1.2) from rat liver exhibited variable sensitivity to assay pH that was dependent upon buffer composition and the cation cofactor. Enzyme activity with 3 mM Mn2+ in excess of Mn2+-GTP was considerably less in Tris buffers above pH 8.0 than in glycine buffer. In the pH range of 6.0-7.6, however, manganese-supported activity was greater in Tris buffers than in imidazole or cacodylate buffers of corresponding pH. The differences in activity seen with various buffers were not apparent when Mg2+ was the sole cation cofactor but were dependent upon Mn2+ concentrations in excess of Mn2+-GTP. The effects of excess Mn2+ on guanylate cyclase varied with assay pH and buffer composition. At pH 7.6 in Tris-HCl buffer, excess Mn2+ increased guanylate cyclase activity with an apparent Ka of 0.25 mM and concentrations above 3 mM were slightly inhibitory. At pH 9.0 in Tris-HCl buffer, however, concentrations of excess Mn2+ above 0.1 mM were strongly inhibitory. By comparison, in cacodylate (pH 7.6) or glycine (pH 9.0) buffers, high concentrations of excess Mn2+ were considerably less inhibitory and the apparent Ka values for excess Mn2+ were...Continue Reading

References

Aug 1, 1977·Proceedings of the National Academy of Sciences of the United States of America·W P ArnoldF Murad
Oct 1, 1977·Proceedings of the National Academy of Sciences of the United States of America·C K Mittal, F Murad
Mar 1, 1975·Metabolism: Clinical and Experimental·H Kimura, F Murad
Jan 1, 1979·Proceedings of the National Academy of Sciences of the United States of America·J M BraughlerF Murad

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Citations

Mar 1, 1989·Biulleten' eksperimental'noĭ biologii i meditsiny·Iu Iu ChirkovL K Starosel'tseva
Jan 25, 1991·European Journal of Pharmacology·H J FülleR Gerzer
Jan 1, 1986·Critical Reviews in Microbiology·F Archibald
Apr 2, 1987·Biochimica Et Biophysica Acta·M M elDeibA A White

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