Interactions of divalent cations and nucleotides with solubilized cardiac guanylate cyclase.
Some properties of guanylate cyclase, which was solubilized from the rabbit heart washed particles by the treatment with Triton X-100, were investigated. The solubilized enzyme activity was stimulated by Mg2+ in the presence of low (subsaturating) Mn2+ (GTP is greater than Mn2+); under these conditions, Ga2+ was inhibitory. At subsaturating MnGTP and free Mn2+, the solubilized enzyme was markedly stimulated by MnGDP and MnATP; CaGTP on the other hand, was inhibitory. These results are consistent with the view that the particulate guanylate cyclase may exist in the cell as a metalloenzyme with tightly bound Mn2+ and that Mg2+ supports its catalysis while Ca2+ as well as nucleotides may exert regulatory effects on its activity.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D006150:Guanine Nucleotides / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000378:metabolism*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D008345:Manganese / Q000494:pharmacology*; D009206:Myocardium / Q000201:enzymology*; D011817:Rabbits; D012265:Ribonucleotides / Q000494:pharmacology*
D006150:Guanine Nucleotides; D012265:Ribonucleotides; D008345:Manganese; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D006162:Guanylate Cyclase; D008274:Magnesium