The vanilloid receptor TRPV1 has been identified as a molecular target for the treatment of pain associated with inflammatory diseases and cancer. Hence, TRPV1 antagonists have been considered for therapeutic evaluation in such diseases. During Phase I clinical trials with AMG 517, a highly selective TRPV1 antagonist, we found that TRPV1 blockade elicited marked, but reversible, and generally plasma concentration-dependent hyperthermia. Similar to what was observed in rats, dogs, and monkeys, hyperthermia was attenuated after repeated dosing of AMG 517 (at the highest dose tested) in humans during a second Phase I trial. However, AMG 517 administered after molar extraction (a surgical cause of acute pain) elicited long-lasting hyperthermia with maximal body temperature surpassing 40 degrees C, suggesting that TRPV1 blockade elicits undesirable hyperthermia in susceptible individuals. Mechanisms of AMG 517-induced hyperthermia were then studied in rats. AMG 517 caused hyperthermia by inducing tail skin vasoconstriction and increasing thermogenesis, which suggests that TRPV1 regulates vasomotor tone and metabolic heat production. In conclusion, these results demonstrate that: (a) TRPV1-selective antagonists like AMG 517 cannot be developed for systemic use as stand alone agents for treatment of pain and other diseases, (b) individual susceptibility influences magnitude of hyperthermia observed after TRPV1 blockade, and (c) TRPV1 plays a pivotal role as a molecular regulator for body temperature in humans.

The binding modes of urokinase-type plasminogen activator (uPA) with five inhibitors (1-(7-sulfonamidoisoquinolinyl) guanidine derivatives) were predicted based on molecular dynamic simulations. MM/PBSA free-energy calculations and MM/GBSA free-energy decomposition analyses were performed on the studied complexes. The calculated binding free energies are reasonably consistent with the experimental results. The free-energy decomposition analyses elucidate the different contributions of the energy of some favorable residues in the interactions between protein and ligand of each complex. The results indicate that the inhibitors mainly interact with the S1 pocket of uPA, wherein the hydrogen bonds and the interactions between guanidines and the corresponding residues play an important role. Moreover, hydrogen bond analyses show the water-mediated hydrogen-bond network near the S1 pocket between uPA, and the ligand probably leads to excellent selectivity of these inhibitors on uPA.

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Structure breaking amino acids, P, S, and G, are incorporated into low immunogenic unstructured zwitterionic peptide fusion proteins. We find unique sequence motifs that exhibit charge balanced conformations and low immunogenicity.