title: Novel peptide inhibitors of angiotensin-converting enzyme 2.
abstract: Angiotensin-converting enzyme 2 (ACE2), a recently identified human homolog of ACE, is a novel metallocarboxypeptidase with specificity, tissue distribution, and function distinct from those of ACE. ACE2 may play a unique role in the renin-angiotensin system and mediate cardiovascular and renal function. Here we report the discovery of ACE2 peptide inhibitors through selection of constrained peptide libraries displayed on phage. Six constrained peptide libraries were constructed and selected against FLAG-tagged ACE2 target. ACE2 peptide binders were identified and classified into five groups, based on their effects on ACE2 activity. Peptides from the first three classes exhibited none, weak, or moderate inhibition on ACE2. Peptides from the fourth class exhibited strong inhibition, with equilibrium inhibition constants (K(i) values) from 0.38 to 1.7 microm. Peptides from the fifth class exhibited very strong inhibition, with K(i) values < 0.14 microm. The most potent inhibitor, DX600, had a K(i) of 2.8 nm. Steady-state enzyme kinetic analysis showed that these potent ACE2 inhibitors exhibited a mixed competitive and non-competitive type of inhibition. They were not hydrolyzed by ACE2. Furthermore, they did not inhibit ACE activity, and thus were specific to ACE2. Finally, they also inhibited ACE2 activity toward its natural substrate angiotensin I, suggesting that they would be functional in vivo. As novel ACE2-specific peptide inhibitors, they should be useful in elucidation of ACE2 in vivo function, thus contributing to our better understanding of the biology of cardiovascular regulation. Our results also demonstrate that library selection by phage display technology can be a rapid and efficient way to discover potent and specific protease inhibitors.
authors.affiliation: Division of Research, Dyax Corporation, 300 Technology Square, Cambridge, MA 02139, USA. lhuang@dyax.com
authors.forename: Lili
authors.initials: L
authors.lastname: Huang
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Sexton
authors.forename: Kirsten
authors.initials: K
authors.lastname: Skogerson
authors.forename: Mary
authors.initials: M
authors.lastname: Devlin
authors.forename: Rodger
authors.initials: R
authors.lastname: Smith
authors.forename: Indra
authors.initials: I
authors.lastname: Sanyal
authors.forename: Tom
authors.initials: T
authors.lastname: Parry
authors.forename: Rachel
authors.initials: R
authors.lastname: Kent
authors.forename: Jasmin
authors.initials: J
authors.lastname: Enright
authors.forename: Qi-long
authors.initials: QL
authors.lastname: Wu
authors.forename: Greg
authors.initials: G
authors.lastname: Conley
authors.forename: Daniel
authors.initials: D
authors.lastname: DeOliveira
authors.forename: Lee
authors.initials: L
authors.lastname: Morganelli
authors.forename: Matthew
authors.initials: M
authors.lastname: Ducar
authors.forename: Charles R
authors.initials: CR
authors.lastname: Wescott
authors.forename: Robert C
authors.initials: RC
authors.lastname: Ladner
mesh_terms: D000595:Amino Acid Sequence; D000085962:Angiotensin-Converting Enzyme 2; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology*; D002268:Carboxypeptidases / Q000037:antagonists & inhibitors*; D008969:Molecular Sequence Data; D019151:Peptide Library; D010455:Peptides / Q000494:pharmacology*; D007703:Peptidyl-Dipeptidase A
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; C556151:DX600 peptide; D019151:Peptide Library; D010455:Peptides; D002268:Carboxypeptidases; D007703:Peptidyl-Dipeptidase A; C000705307:ACE2 protein, human; D000085962:Angiotensin-Converting Enzyme 2