Geometry of proline-containing alpha-helices in proteins

Crystal structure analysis of proline-containing α-helices in proteins has been carried out. High resolution crystal structures were selected from the Protein Data Bank. Apart from the standard internal parameters, some parameters which are specifically related to the bend in the helix due to proline have been developed and analyzed. Finally the position and nature of these helices and their interactions with the rest of the protein have been analyzed.     

Characterization of growth hormone releasing factor analog expression in Saccharomyces cerevisiae

An analog of growth hormone releasing factor (GRF), [Leu²⁷]GRF(1-40)-OH, has been expressed and secreted in Saccharomyces cerevisiae under the control of the α-factor gene promoter and prepro sequence. A single pair of consecutive basic residues served as a processing site between the a-factor sequences and the GRF sequences. [Leu²⁷]GRF(1-40)-OH from fermentor broth containing 20-30 mg/L of immuno-reactive peptides was shown to be correctly processed and to possess biological activity as measured in vitro and in vivo. Additional peptides purified from broth appear to result from proteolytic degradation of the original translation product. Analysis of the amino acid compositions and sequences of these peptides suggests that processing enzymes may be responsible for some of the degradation.