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

Abstract

A molecular model has been developed for human Big Endothelin-l, which is the immediate precursor to the potent vasoconstrictor polypeptide endothelin-1 and the target of the highly specific endothelin converting enzyme. This model is produced by a threading algorithm protocol and is consistent with all the currently available structural and biochemical data for this molecule.

Identification of amino acid residues in the C-terminal tail of big endothelin-1 involved in processing to endothelin-1

“…Interestingly, we previously demonstrated that, when (Lys 9 < Glu)PPET-1 and (Lys 9 <Ala)PPET-1 cDNAs were transiently expressed in COS-7 cells, the conversion of mutant big ET-1 analogs to ET-1 was similar to that of wild type, suggesting that these mutations did not interfere with the processing by ECE . These findings, however, were different from those obtained with Lys 9 -modified big ET-1 analogs (Corder 1996). One possible explanation of this difference might be that functional groups incorporated into Lys 9 are quite bulky and disrupt the bond between Ser 38 and Lys 9 , whereas Ala or Glu substitution did not affect the compact structure of big ET-1.…”

“…The structure is further compacted by a turn generated by hydrogen bonding between Ser 35 and Ser 38 bringing the side chain of Ser 38 in close contact with Lys 9 . As a previous study (Corder 1996) reported that the conversion rate of big ET-1 analogs, in which Lys 9 residue was chemically modified, was substantially reduced, it was argued that this residue forms a hydrogen bond with Ser 38 and stabilizes the big ET-1 structure (Peto et al 1996). In the present study, the replacement of Ser 35 with Asn, which is the corresponding residue in big ET-2 and big ET-3, affected the cleavage and resulted in lower ET-1 production.…”

“…Our results are in good agreement with these studies. Using the full-length mutant big ET-1 analogs expressed in a mammalian expression system, we showed that Recently, a molecular model for big ET-1 was reported in which the structure of the endothelin core was almost identical to the crystal structure of ET-1 (Peto et al 1996). In their big ET-1 structure (Fig.…”

“…For example, (Pro 25 <Ala)PPET-1 and  5. The ribbon diagram of the molecular model of big ET-1 (modified from Peto et al 1996). The proposed hydrogen bonds in the structure are indicated by the dashed lines.…”

Novel activity of endothelin-converting enzyme: hydrolysis of bradykinin

“…This was not due to ECE activity, since it was not inhibitable by 100 µM phosphoramidon. Non-transfected CHO cells hydrolysed 100 µM Phe-Arg to the same extent as transfected cells, Table 1 Comparison of ECE specificity, using BK, [Phe 22 ]big ET-1- (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)…”