phosphoramidon and retrothiorphan

Human skin fibroblasts produce in culture an elastase-type metalloendopeptidase which can hydrolyze synthetic elastase-substrate as Suc ala3 pNA and degrade also elastic fibers when injected in the dermis or deposited on cryostat-skin sections [3-8]. Here we describe further characterization of this enzyme activity using metallo-enzyme inhibitors as well as specific inhibitors of known Zn-endopeptidases such as angiotensin converting enzyme and enkephalinase. Among the metal complexing agents tested only EDTA and o-phenanthrolin could inhibit the elastase-type activity of fibroblasts, other known metal complexing substances capable of reacting with Zn (2,2' dipyridyl, diethyl dithiocarbamate and other metal chelators) were ineffective as was also lisinopril, an ACE-inhibitor [13]. Phosphoramidon and retrothiorphan, specific enkephalinase inhibitors [12] did strongly inhibit the elastase type activity of human skin fibroblasts (IC50 10(-8) M). Ethanol at conc-s used to dissolve organic, water insoluble inhibitors (50-100 microliters/ml) strongly inhibited the enzyme. It appears that the metal prosthetic group of fibroblast elastase (presumably, Zn) is not directly accessible to several of the low M. Wt complexing agents. The efficiency of enkephalinase inhibitors suggest a possible relationship between this enzyme and fibroblast-elastase.

Topics: Adult; Female; Fibroblasts; Glycopeptides; Humans; Neprilysin; Pancreatic Elastase; Protease Inhibitors; Skin; Thiorphan