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Nanomolar Binding Of Peptides Containing Noncanonical Amino Acids By A Synthetic Receptor, Leigh Logsdon, Christopher Schardon, Vijayakumar Ramalingam, Sharon Kwee, Adam Urbach
Nanomolar Binding Of Peptides Containing Noncanonical Amino Acids By A Synthetic Receptor, Leigh Logsdon, Christopher Schardon, Vijayakumar Ramalingam, Sharon Kwee, Adam Urbach
Adam R Urbach
This paper describes the molecular recognition of phenylalanine derivatives and their peptides by the synthetic receptor cucurbit[7]uril (Q7). The 4-tert-butyl and 4-aminomethyl derivatives of phenylalanine (tBuPhe and AMPhe) were identified from a screen to have 20–30-fold higher affinity than phenylalanine for Q7. Placement of these residues at the N-terminus of model tripeptides (X-Gly-Gly), resulted in no change in affinity for tBuPhe-Gly-Gly, but a remarkable 500-fold increase in affinity for AMPhe-Gly-Gly, which bound to Q7 with an equilibrium dissociation constant (Kd) value of 0.95 nM in neutral phosphate buffer. Structure–activity studies revealed that three functional groups work in a positively cooperative …
Sequence-Specific Inhibition Of A Nonspecific Protease, Leigh Logsdon, Adam Urbach
Sequence-Specific Inhibition Of A Nonspecific Protease, Leigh Logsdon, Adam Urbach
Adam R Urbach
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 …