Heme deficiency of soluble guanylate cyclase in rat platelets

• Published in: Biokhimiia (Moscow, Russia) Vol. 56; no. 3; p. 487
• Main Authors: Busygina, O G, Severina, I S
• Format: Journal Article
• Language: Russian
• Published: Russia (Federation) 01-03-1991
• Subjects: Animals; Blood Platelets - enzymology; Chromatography, DEAE-Cellulose; Dithiothreitol - chemistry; Enzyme Activation; Guanylate Cyclase - metabolism; Heme - deficiency; Hemoglobins - chemistry; Male; Nitroprusside; Rats; Solubility; Spectrum Analysis
• ISSN: 0320-9725

Analysis of soluble guanylate cyclase of rat platelets (105,000 g supernatant) revealed no activating effect of sodium nitroprusside on the enzyme activity. Dithiothreitol (2 x 10(-4) H) added to the sample stimulated the basal activity of guanylate cyclase in the presence of Mg2+ but did not induce the enzyme activation by sodium nitroprusside. Hemoglobin added to the enzyme did not influence its basal activity or the activating effect of sodium nitroprusside. DEAE-Cellulose chromatography of the 105,000 g supernatant revealed two protein peaks, I and II, of which only peak II possessed a guanylate cyclase activity. Fraction I added to a partly purified enzyme did not change the enzyme activity, nor did it enhance the sodium nitroprusside-induced activation of guanylate cyclase. Spectral analysis of the 105,000 g supernatant revealed that the presence of a maximum at 415-425 nm (Soret band) depended on the degree of plasma hemolysis. In the absence of hemolysis the Soret band was unobserved either in the 105,000 g supernatant or in fractions I and II. It is suggested that rat platelet guanylate cyclase is present in these cells in a heme-deficient state.