Modifies a noun

• monophosphate: It activates the enzyme guanylate cyclase, resulting in an increased level of cyclic guanosine monophosphate ( cGMP ) in the corpus cavernosum.

• triphosphate: G-proteins are so called because they bind the guanine nucleotides guanosine triphosphate ( GTP ) and guanosine diphosphate ( GDP ).