title: Synthesis of peptidyl ene diones: selective inactivators of the cysteine proteinases.
abstract: A series of synthetic peptides in which the C-terminal carboxyl grouping (-CO(2)H) of each has been chemically converted into a variety of ene dione derivatives (-CO-CH=CH-CO-X; X = -H, -Me, -OBut, -OEt, -OMe, -CO-OMe), have been prepared and tested as inactivators against typical members of the serine and cysteine protease families. For example, the sequences Cbz-Pro-Phe-CH=CH-CO-OEt (I) which fulfils the known primary and secondary specificity requirements of the serine protease chymotrypsin, and Cbz-Phe-Ala-CH=CH-CO-OEt (II) which represents a general recognition sequence for cysteine proteases such as cathepsins B, L and S, have been tested as putative irreversible inactivators of their respective target proteases. It was found that, whereas II, for example, functioned as a time-dependent, irreversible inactivator of each of the cysteine proteases, I behaved only as a modest competitive reversible inhibitor of chymotrypsin. Within the simple ester sequences Cbz-Phe-Ala-CH=CH-CO-R, the rank order of inhibitor effectiveness decreases in the order R = -OMe > -OEt >> -OBut. It was also found that the presence of both an unsaturated double bond and an ester (or alpha-keto ester) moiety were indispensable for obtaining irreversible inactivators. Of the irreversible inactivators synthesized, Cbz-Phe-Ala-CH=CH-CO-CO-OEt (which contains a highly electrophilic alpha-keto ester grouping) was found to be the most effective exhibiting, for example, second-order rate constants of approximately 1.7 x 10(6)M(-1)min(-1) and approximately 4.9 x 10(4)M(-1)min(-1) against recombinant human cathepsin S and human spleenic cathepsin B, respectively. This initial study thus holds out the promise that this class of inactivator may well be specific for the cysteine protease subclass.
authors: School of Chemistry, Queen's University of Belfast, David Keir Building, Belfast BT9 5AG, UK.
authors: Paul
authors: P
authors: Darkins
authors: Brendan F
authors: BF
authors: Gilmore
authors: Susan J
authors: SJ
authors: Hawthorne
authors: Adrienne
authors: A
authors: Healy
authors: Hazel
authors: H
authors: Moncrieff
authors: Noreen
authors: N
authors: McCarthy
authors: M Anthony
authors: MA
authors: McKervey
authors: Dieter
authors: D
authors: Brömme
authors: Maurice
authors: M
authors: Pagano
authors: Brian
authors: B
authors: Walker
mesh_terms: D002087:Butyrates / Q000737:chemistry; D002384:Catalysis; D002403:Cathepsins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D003545:Cysteine / Q000737:chemistry; D015853:Cysteine Proteinase Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D004952:Esters / Q000737:chemistry; D007700:Kinetics; D008745:Methylation; D015394:Molecular Structure; D009574:Nitro Compounds / Q000737:chemistry; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: C508635:6-(nitrooxy)hexyl-(2z)-4-(acetyloxy)-3-(4-(methylsulfonyl)phenyl)-2-phenylbut-2-enoate; D002087:Butyrates; D015853:Cysteine Proteinase Inhibitors; D004952:Esters; D009574:Nitro Compounds; D010455:Peptides; D002403:Cathepsins; D003545:Cysteine