Brian L. Bray

Second virial coefficient determination of a therapeutic peptide by self‐interaction chromatography

Self‐interaction of macromolecules has been shown to play an important role in a number of physical processes, including crystallization, solubility, viscosity, and aggregation. Peptide self‐interaction is not as well studied as for larger proteins, but should play an equally important role. The osmotic second virial coefficient, B, can be used to quantify peptide and protein self‐interaction. B values are typically measured using static light scattering (SLS). Peptides, however, do not scatter enough light to allow such measurements. This study describes the first use of self‐interaction chromatography (SIC) for the measurement of peptide B values because SIC does not have the molecular size limitations of SLS. In the present work, SIC was used to measure B for enfuvirtide, a 36‐amino acid therapeutic peptide, as a function of salt concentration, salt type, and pH. B was found to correlate strongly with solubility and apparent molecular weight. In general, the solubility of enfuvirtide increases with pH from 6 to 10 and decreases as the salt concentration increases from 0 to 0.5M for three different salts. The effect of peptide concentration on B was also investigated and shown to have a significant effect, but only at high concentrations (>80 mg/mL).

Pharmacokinetics and tolerability of the new second-generation nonnucleoside reverse- transcriptase inhibitor KM-023 in healthy subjects.

Background KM-023 is a new second-generation nonnucleoside reverse-transcriptase inhibitor that is under development for the treatment of human immunodeficiency virus (HIV) type 1 infection. Objective This study determined KM-023 tolerability and pharmacokinetic characteristics in healthy subjects. Materials and methods A randomized, double-blinded, placebo-controlled, dose-escalation study was conducted in 80 healthy South Korean male volunteers. The subjects were allocated to single- or multiple-dose (once daily for 7 days) groups that received 75, 150, 300, or 600 mg drug or placebo in a 4:1 ratio. Safety and pharmacokinetic assessments were performed during the study. Plasma and urine concentrations were quantified using liquid chromatography–tandem mass spectrometry. Results The average maximum concentration (Cmax) and area under the concentration–time curve from time 0 to infinity (AUC∞) values of KM-023 for the 75–600 mg doses in the single-dose study ranged from 440.2 ng/mL to 1,245.4 ng/mL and 11,142.4 ng · h/mL to 33,705.6 ng · h/mL, respectively. Values of the mean Cmax at a steady state and AUC within the dosing interval ranged from 385.1 ng/mL to 1,096.7 ng/mL and 3,698.9 ng · h/mL to 10,232.6 ng · h/mL, respectively, following 75–600 mg doses in the multiple-dose study. Dose proportionality was not observed for KM-023. KM-023 showed a 0.6-fold accumulation after multiple doses in the 600 mg dose group. The mean half-life values ranged between 20.7 and 31.2 hours. KM-023 was generally well tolerated without serious adverse events. Conclusion KM-023 demonstrated dose- and time-dependent nonlinear pharmacokinetic characteristics after single or multiple doses over a dose range (75–600 mg) in healthy subjects. KM-023 showed favorable tolerability in this study. This Phase I clinical trial information can be used to design further clinical studies appropriately to evaluate KM-023 in patients with HIV-1 infection.

Convergent synthesis of a helical, prehairpin HR1 trimer from HIV gp41

A helical, prehairpin trimer covering the majority of the HR1 region of human immunodeficiency virus gp41 was achieved by chemically coupling three identical 51 amino acid peptides. A 1,3,5‐tris(aminomethyl)‐2,4,6‐triethylbenzene pinwheel ‘cap’ was used to trimerize the peptides by taking advantage of the unique property of triacyl fluoride and orthogonal protection and deprotection. The resulting protein is fully helical, highly thermostable and soluble. Copyright