Effect of GTP analogues on purified soluble guanylate cyclase.
1982; Elsevier BV; Volume: 257; Issue: 3 Linguagem: Inglês
10.1016/s0021-9258(19)68192-5
ISSN1083-351X
AutoresHarvey Brandwein, John Lewicki, Scott A. Waldman, Ferid Murad,
Tópico(s)Algal biology and biofuel production
ResumoIn our studies with purified soluble guanylate cyclase from rat lung, we have tested a number of guanosine 5"triphosphate (GTP) analogues as substrates and inhibitors.5'-Guanylylimidodiphosphate (GMP-P(NH)P), guanylyl @,y-methylene) diphosphate (GMP-P(CHz)P), and guanosine 5'-0-(3-thiotriphosphate) (GTPyS) were found to be substrates for guanylate cyclase.GTPyS supported cyclic GMP formation at 20 or 75% of the rate seen with Mn2'-GTP and M8+-GTP, respectively.GMP-P(NH)P and GMP-P(CH2)P supported cyclic GMP formation at 10-2076 of the GTP rate with either cation cofactor.These analogues were found to have multiple K , values; one K , value was similar to GTP (150 p~ with M g + , 20-70 p~ with Mn2+), but an additional high affinity catalytic site (3 p ~) was also observed.Guanosine tetraphosphate (Ki = 10 PM), adenosine triphosphate (Ki = 9 p ~) and the 23'-dialdehyde derivative of GTP (dial GTP) (Kt = 1 p ~) were not good substrates for the enzyme; however, they were potent competitive inhibitors.These GTP analogues will be useful tools for the study of GTP binding sites on guanylate cyclase and they may also help elucidate the effects of free radicals and other agents on guanylate cyclase regulation.
Referência(s)