title: Sequence-specific inhibition of a nonspecific protease.
abstract: A nonspecific exopeptidase, aminopeptidase N (APN), is inhibited sequence-specifically by a synthetic host, cucurbit[7]uril (Q7), which binds with high affinity and specificity to N-terminal phenylalanine (Phe) and 4-(aminomethyl)phenylalanine (AMPhe) and prevents their removal from the peptide. Liquid chromatography experiments demonstrated that in the presence of excess Q7, APN quantitatively converts the pentapeptides Thr-Gly-Ala-X-Met into the dipeptides X-Met (X = Phe, AMPhe). The resulting Q7-bound products are completely stable to proteolytic digestion for at least 24 h. Structure-activity studies revealed a direct correlation between the extent of protection of an N-terminal amino acid and its affinity for Q7. Therefore, Q7 provides predictable sequence-specificity to an otherwise nonspecific protease and enables the production of a single peptide product. Conversely, APN uncovers a high-affinity epitope that is subsequently bound by Q7, and thus this approach should also facilitate the molecular recognition of peptides.
authors.affiliation: Department of Chemistry, Trinity University, 1 Trinity Place, San Antonio, Texas 78212, USA.
authors.forename: Leigh A
authors.initials: LA
authors.lastname: Logsdon
authors.forename: Adam R
authors.initials: AR
authors.lastname: Urbach
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001952:Bridged-Ring Compounds / Q000378:metabolism*; D018826:CD13 Antigens / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism*; D007093:Imidazoles / Q000378:metabolism*; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D010649:Phenylalanine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity; D013552:Swine; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils
chemical_list: D001952:Bridged-Ring Compounds; D018826:CD13 Antigens; D007093:Imidazoles; D010455:Peptides; D010649:Phenylalanine; C456276:cucurbit(7)uril; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils; C090347:4-aminomethylphenylalanine