title: Human leukocyte migration inhibitory factor (LIF). IV. 3',5'-cGMP protects LIF against inactivation by the esterase inhibitor phenylmethylsulfonyl fluoride.
abstract: Recently reported experiments suggest that human leukocyte migration inhibitory factor (LIF) has properties of an esterase and a protease with substrate specificities directed against arginine esters and amides. Also reported previously, the synthetic phosphodiester bis-p-nitrophenyl phosphate (BNPP) but not various phosphomonoesters preserve LIF activity in the presence of the serine esterase inhibitor phenylmethylsulfonyl fluoride (PMSF). In this paper I demonstrate that guanosine 3'5'-cyclic monophosphoric acid (3',5'-cGMP), a naturally occurring phosphodiester, at concentrations in excess of 10(-5)M also protects LIF against PMSF inactivation. The effect seems specific for the diester bond, its position in the nucleotide, and the guanine base. The possibility that LIF may be a multifunctional or an allosteric enzyme regulated by 3',5'-cGMP is discussed.
mesh_terms: D000242:Cyclic AMP; D006152:Cyclic GMP / Q000494:pharmacology*; D004950:Esterases / Q000037:antagonists & inhibitors; D006801:Humans; D007962:Leukocytes; D008263:Macrophage Migration-Inhibitory Factors; D010664:Phenylmethylsulfonyl Fluoride / Q000494:pharmacology*; D013450:Sulfones / Q000494:pharmacology*
chemical_list: D008263:Macrophage Migration-Inhibitory Factors; D013450:Sulfones; D010664:Phenylmethylsulfonyl Fluoride; D000242:Cyclic AMP; D004950:Esterases; D006152:Cyclic GMP