ISOLATION OF NITRIC-OXIDE SYNTHASE IN THE RAT UTERUS

Nitric oxide synthase (NOS) was isolated from the uterus of adult fema le rats by diethylaminoethyl (DEAE) column and further purified by 2', 5'-ADP agarose. The chromatographic properties revealed two isoenzymes , NOS, and NOS2. The molecular weights of both isoenzymes was approxim ately 155 Kd by sodium dodecyl sulfate-polyacrylamide gel electrophore sis (SDS PAGE) which was similar to NOS1 and NOS2 from rat brain. The enzymes required nicotinamide adenine dinucleotide phosphate (NADPH), Ca+2 and calmodulin as cofactors. However, in the absence of calmoduli n and/or calcium NOS, was reduced by approximately 96%, while NOS2 was reduced by approximately 70%. This maximal enzyme activity was simila r for brain. These results demonstrate that two isoforms of NOS are pr esent in the rat uterus.