title: A high-affinity competitive inhibitor of type A botulinum neurotoxin protease activity.
abstract: The peptide N-acetyl-CRATKML-amide is an effective inhibitor of type A botulinum neurotoxin (BoNT A) protease activity [Schmidt et al., FEBS Lett. 435 (1998) 61-64]. To improve inhibitor binding, the peptide was modified by replacing cysteine with other sulfhydryl-containing compounds. Ten peptides were synthesized. One peptide adapted the structure of captopril to the binding requirements of BoNT A, but it was a weak inhibitor, suggesting that angiotensin-converting enzyme is not a good model for BoNT A inhibitor development. However, replacing cysteine with 2-mercapto-3-phenylpropionyl yielded a peptide with K(i) of 330 nM, the best inhibitor of BoNT A protease activity reported to date. Additional modifications of the inhibitor revealed structural elements important for binding and supported our earlier findings that, with the exception of P1' arginine, subsites on BoNT A are not highly specific for particular amino acid side chains.
authors.affiliation: Toxinology and Aerobiology Division, United States Army Medical Research Institute of Infectious Diseases, 1425 Porter St., Fort Detrick, MD 21702-5011, USA. james.schmidt@det.amedd.army.mil
authors.forename: James J
authors.initials: JJ
authors.lastname: Schmidt
authors.forename: Robert G
authors.initials: RG
authors.lastname: Stafford
mesh_terms: D001667:Binding, Competitive; D019274:Botulinum Toxins, Type A / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D020134:Catalytic Domain; D002851:Chromatography, High Pressure Liquid; D007700:Kinetics; D008956:Models, Chemical; D010452:Peptide Biosynthesis; D010455:Peptides / Q000737:chemistry; D011480:Protease Inhibitors / Q000494:pharmacology*; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity
chemical_list: D010455:Peptides; D011480:Protease Inhibitors; D019274:Botulinum Toxins, Type A