Billy D. Vineyard

α-Amino acids by catalytic asymmetric hydrogenation

Abstract Over the past decade the field of asymmetric hydrogenation has proliferated. It is now one of the best understood catalytic reactions. Enantiomeric excesses greater than 95% can be achieved with α-acylaminoacrylic acids, amino acid precursors. Excellent enantioselectivity can also be obtained with other prochiral olefins.

Amphiphilic growth hormone releasing factor (GRF) analogs: Peptide design and biological activity in vivo

The first twenty-nine amino acids of human Growth Hormone Releasing Factor (hGRF) possess a distinct amphiphilic character. This is seen as twisted hydrophobic and hydrophilic bands in the helical net projection. Four amidated analogs were designed by optimizing amphiphilic and helical potentials of the native sequence. These designed analogs, with up to eight-amino acid changes, were tested in sheep via intravenous injection. The growth hormone-stimulating activities of the analogs were significantly higher when compared to bovine Growth Hormone Releasing Factor (bGRF44-NH2). This suggests that the amphiphilic conformation of GRF(1-29) is important to the receptor.

Chemical synthesis of bovine transforming growth factor-α: Synthesis, characterization and biological activity

Bovine transforming growth factor-alpha (bTGF-alpha) is a 50 amino acid polypeptide with three disulfide linkages. In order to evaluate the biological function of this peptide, bTGF-alpha was synthesized via an automatic synthesizer and purified to homogeneity in high yield. The integrity of this synthetic peptide was confirmed by chemical analyses and bioassays. In a bovine liver radioreceptor assay, bTGF-alpha competes with radiolabeled EGF and has activity comparable to mEGF and hTGF-alpha. Compared to hEGF, bTGF-alpha elicits a greater response in a bovine mammary cell proliferation.

Use of X-ray Crystal Structure in the Study of Asymmetric Catalysis

A considerable number of efficient asymmetric hydrogenation catalysts based on complexes of rhodium and a chiral bisphosphine have been reported. These are highly effective only on enamide precursors of α-amino acids or other closely related systems capable of chelating with the metal. Examination of x-ray crystal structures of the metal complexes has indicated that all these diverse structures may be working by a common mechanism.