Biomedical subjects
Publications and source records attributed to Jennifer A Kowalski.
The cytotoxic, cyclic heptadepsipeptide, natural product callipeltin B was synthesized on a solid-phase support in 15% overall yield. Comparison of the 1H NMR spectra of three synthetic isomers with those of callipeltin B confirmed the configurational reassignment of its threonine residues as d-allothreonine and the assignment of the configuration of its beta-methoxytyrosine residue as (2R,3R).
A new procedure that employs a one-pot, oxidative Hofmann rearrangement to incorporate a urea linkage into peptide backbones is detailed herein. This methodology was used to replace the scissile peptide bonds of [Leu5]enkephalin and a hexapeptide HIV-1 protease substrate. The [Leu5]enkephalin analogue was found to inhibit cleavage of hippurylhistidylleucine (HHL) by porcine kidney angiotensin-converting enzyme (PK-ACE) with a 0.88 mM IC50 value, comparable to the Michaelis constant of [Leu5]enkephalin with the same enzyme. The HIV-1 protease substrate analogue was shown to inhibit HIV-1 protease with an IC50=34 microM.
The NMR solution structure of the isolated Apo Pin1 WW domain (6-39) reveals that it adopts a twisted three-stranded antiparallel beta-sheet conformation, very similar to the structure exhibited by the crystal of this domain in the context of the two domain Pin1 protein. While the B factors in the apo x-ray crystal structure indicate that loop 1 and loop 2 are conformationally well defined, the solution NMR data suggest that loop 1 is quite flexible, at least in the absence of the ligand. The NMR chemical shift and nuclear Overhauser effect pattern exhibited by the 6-39 Pin1 WW domain has proven to be diagnostic for demonstrating that single site variants of this domain adopt a normally folded structure. Knowledge of this type is critical before embarking on time-consuming kinetic and thermodynamic studies required for a detailed understanding of beta-sheet folding.
Described herein is the development of a robust synthetic route applicable to parallel synthesis of diverse 2-carboxamide-3-amino-substituted quinoxalines. In addition to the scope and limitations of the methods developed, a purification strategy employing solid-phase extraction (SPE) and application of the methods to a small parallel array of compounds are discussed.