ki: 8.8 nm2-guanidinoethylmercaptosuccinic acid is a carboxypeptidase e inhibitor.carboxypeptidase e, also known as enkephalin convertase, can remove c-terminal residues during the processing of propeptides, such as enkephalin and proinsulin.
2-guanidinoethylmercaptosuccinic acid was identified as a biproduct analogs of lysine and arginine that showed potent inhibitory effect on enkephalin convertase with the ki value of 8.8 nm. in addition, 2-guanidinoethylmercaptosuccinic acid was found to be several hundred fold more potent towards enkephalin convertase than towards carboxypeptidase b or n and the kinetic analyses indicated the pure competitive nature of the inhibition [1].
previous study found that following the intrathecal administration of 2-guanidinoethylmercaptosuccinic acid at 12.5, 25 and 50 micrograms, an increase in the tail-flick latency was seen. in addition, 2-guanidinoethylmercaptosuccinic acid could potentiate the analgesic effects of the intrathecally applied met5-enkephalin-arg6-phe7 and met5-enkephalin-arg6-gly7-leu8. all these effects of 2-guanidinoethylmercaptosuccinic acid were significantly attenuated by the treatment of naloxone. moreover, the rats subjected to chronic pain showed a weaker analgesic response to the treatment of 2-guanidinoethylmercaptosuccinic acid. furthermore, 2-guanidinoethylmercaptosuccinic acid bound to enkephalin convertase in the spinal cord of these rats produced only a slight increase in kd [2].
1. fricker ld, plummer th jr, snyder sh. enkephalin convertase: potent, selective, and irreversible inhibitors. biochem biophys res commun. 1983 mar 29;111(3):994-1000.2. m. bommer, k. nikolarakis, e. p. noble, et al. in vivo modulation of rat hypothalamic opioid peptide content by intracerebroventricular injection of guanidinoethylmercaptosuccinic acid (gemsa): possible physiological role of enkephalin convertase. brain research 492(1-2), 305-313 (1989).
