Endothelial nitric oxide synthase ( eNOS ) is one of three enzymes capable of producing nitric oxide ( NO) . This molecule fully key functions in the cardiovascular system . ENOS gene consists of 26 exons and the fragment of chromosome 7 is about the size of 22 kb. Gene promoter does not contain a basic sequence recognized by a complex of RNA polymerase II preinicjacyjny , tzw.TATA box .