In vitro degradation of endothelin-1 by endopeptidase 24.11 (enkephalinase)

A molecular model for human Big‐Endothelin‐1 (Big ET‐1)

“…3). Bonds that are cleaved by various proteases in ET-I but not Big ET-1, include Ser-5 Leu-6, His-16-Leu-17, and Asp-18-Ile-19 [29][30][31][32]. In all these cases, at least one residue of the pair is less than 50% exposed in Big ET-1, and also in all cases, there is a notable reduction in accessibilities from those in ET-1 (where all residues are > 50% exposed).…”

Enzymatic degradation of endothelin-1 by activated human polymorphonuclear neutrophils

“…Incubation of unlabelled ET-1 with purified cathepsin G allowed to identify a major cleavage site corresponding to the Hisl6-Leu x7 bond, leading to the formation of inactive [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] fragments and the C-terminal pentapeptide.…”

“…This specificity is observed in the hydrolysis of the His-Leu bond of ET-1. The cleavage of this bond, generating [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] fragments and the C-terminal pentapeptide (Table I) is sufficient to induce a biological activity loss of ET-1. Indeed, we have previously shown that [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] peptides, resulting from the hydrolysis of ET-1 by endopeptidase 24.11, were devoid of vasoconstrictor effect on isolated rat aortic rings [9].…”

“…5). They were collected and submitted to amino acid analysis, Peaks 1, 2, 3 had amino acid compositions compatible with the sequence ET-1 [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] and probably differed from each other by additional cleavages in the disulfidelinked loops (Table I) had a composition identical to that of ET-1 and might differ from the intact substrate by one or more cleavages inside the disulfide-linked loops. Peak 6 was present as a double peak due to the appearance of a metabolite not resolved from ET-1.…”

“…Mechanisms of the peptide removal include binding to specific receptors, urinary excretion and probably enzymatic inactivation. A role for endopeptidase 24.11 (enkephalinase; neutral endopeptidase; EC 3.4.24.11) (E-24.11), a membrane bound metalloenzyme, has been hypothesized from in vitro data showing degradation of ET-1 by proximal tubular membranes from human kidney [9] and by purified E-24.11 [9,10,11].…”