This project focuses on structural design, chemical synthesis and modification of polypeptide important to reproductive and developmental biology. A. Human corticortropin releasing factor. Ten peptides corresponding to the sequence 9-41 to 17-41 of hCRF were synthesized and purified in order to test the role of Arg16 on the face of the postulated Alpha helical form of the hormone in the expression of agonist or antagonist activity. Results indicate a 2-3 order increase in binding to rat pituitary membrane receptor on addition of Arg16 with a general increase in binding on elongation. However, the shorter fragments 11- and 12-41 binds more strongly than the longer 9- and 10-41 peptides. Agonist activity is expressed in fragments of length 4-41 with antagonist activity peaking at 11- and 12-41, and re-expression of agonist activity in the still shorter fragments 14- and 15-41. These results indicate the importance of Arg16 as a critical residues for expression of activity in hormone. B. Dimeric gonadotropin releasing hormone agonists. Three dimeric des-Gly10-[D-Lys6]-GnRH-NHEt cross-linked at the Epsilon-amino group of D-Lys6 with -Glyn-COCH2-CO-Glyn- (Ia, n=0; Ib, n=1; Ic, n=2) were synthesized, purified and evaluated for their biological activities. Results indicate that cross-linking of an agonist into dimers enhances both in vivo and in vitro biological activities. The dimer Ib exhibits the highest anti-fertility effect ever reported. C. Human transferrin receptor peptides. Two peptides of 14 and 18 amino acid residues corresponding to an Alpha helical and helix turn region of the cytoplasmic portion of the human transferrin receptor were synthesized for use as immunogens. The antibodies are to be used in a study of the function of these domains in receptor dynamics and regulation. D. A peptide of 22 amino acid residues in a protein expressed during gastrulation of Xenopus laevis has been synthesized.
