title: Guanylate cyclase in Escherichia coli. Purification and properties.
abstract: Guanylate cyclase has been purified from extracts of Escherichia coli. After a 1000-fold purification, the enzyme contains only minor contaminants as judged by disc gel electrophoresis. The Km for GTP is approximately 7 times 10(-5) M and the optimal pH is 8.0. More activity is observed with Mn2+ than with Mg2+, and maximal activity is observed at 0.14 mM Mn2+ and 1.4 mM Mg2+. Based on its behavior on Sephadex G-100, the molecular weight of E. coli guanylate cyclase is about 30,000. Disc gel electrophoretic analysis indicates that the enzyme consists of a single polypeptide chain. Guanylate cyclase does not form 3':5'-AMP from ATP, and therefore, is distinct from adenylate cyclase.
mesh_terms: D004789:Enzyme Activation / Q000187:drug effects; D004926:Escherichia coli / Q000201:enzymology*; D006162:Guanylate Cyclase / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D008970:Molecular Weight
chemical_list: D008345:Manganese; D006162:Guanylate Cyclase; D008274:Magnesium