title: Synthesis and kinetic studies of an amidine-containing phosphonofluoridate: a novel potent inhibitor of trypsin-like enzymes.
abstract: The amidine-containing alpha-aminoalkyl phosphonofluoridate 3 (Cbz-(4-AmPhGly)P(OPh)(F)) is a very potent inhibitor of trypsin-like enzymes. It was prepared by hydrolyzing the corresponding phosphonate diphenyl ester 4 followed by reaction of fluoride with the phosphonochloridate prepared from the intermediate phosphonic acid monoester 5. Compound 3 is the most potent amidine-containing organophosphorus inhibitor yet reported for trypsin-like enzymes. It inhibits trypsin and thrombin with second-order rate constants (Kobs/[I]) of 2.6 x 10(5) M-1 s-1 and 1.0 x 10(5) M-1 s-1, respectively, showing a 130-fold and a 1250-fold rate enhancement over the corresponding diphenyl ester (4). It also inactivates trypsin 2 orders of magnitude more potently than simple phosphonofluoridates such as DFP,1 Sarin and Soman. The phosphonofluoridate 3 does not inhibit other serine proteases such as porcine pancreatic elastase (PPE) and the esterase acetylcholinesterase (AChE). The phosphonofluoridate 3 is hydrolyzed rapidly in buffer solution and has a t1/2 of 4.5 s at pH 7.5.
authors.affiliation: School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta 30332-0400, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Ni
authors.forename: J C
authors.initials: JC
authors.lastname: Powers
mesh_terms: D000578:Amidines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D004795:Enzyme Stability; D007700:Kinetics; D009943:Organophosphorus Compounds / Q000138:chemical synthesis* / Q000494:pharmacology*; D015842:Serine Proteinase Inhibitors / Q000138:chemical synthesis* / Q000378:metabolism / Q000494:pharmacology*; D014361:Trypsin Inhibitors / Q000138:chemical synthesis* / Q000494:pharmacology
chemical_list: D000578:Amidines; D009943:Organophosphorus Compounds; D015842:Serine Proteinase Inhibitors; D014361:Trypsin Inhibitors; C116517:phenyl N-benzyloxycarbonylamino-(4-amidinophenyl)methyl phosphonofluoridate