This research program focuses on the structure and function of the angiotensin II (AngII) and gonadotropin releasing hormone (GnRH) receptors. Recent studies include: (1) In addition to the previously reported four segments of the murine GnRH receptor (residues 19-77, 138-194, 232-298 and 265-359) each fused with maltose-binding protein (MBP), an N-terminal segment (residues 1-77) were also fused with MBP and over- expressed in E. coli strain DH5 . Immunization of rabbits with this MBP-fusion proteins for the production of antibodies is in progress. (2) Diarylketone is relatively stable and reacts irreversibly and preferentially with C-H bonds upon photolysis. We therefore chemically synthesized p-benzoyl-L- phenylalanine (Bpa) and incorporated Bpa into tyrosine or phenylalanine of AngII and GnRH. In addition to previously described [Sar1, Bpa8 ]AngII, and [Bpa1]AngII, [Bpa3, D-Ala6]- GnRH was synthesized by the solid phase method. Functional characterization of [Bpa3, D-Ala6]-GnRH is now in progress. (3) Human chorionic gonadotropin (hCG) preparations contain activity against the human immunodeficiency virus type 1 (HIV- 1). However, there has been controversy about whether some biological activities of hCG and hCG -subunit preparations are due to the -subunit itself, or to other proteins present in the preparations. We have achieved the purification, characterization, and identification of lysozyme, ribonuclease (RNase) A and RNase U as anti-HIV activity present in the - core fraction of hCG prepared from the urine of pregnant women. In addition to HIV-1 inhibition by means of p24 production in ACH2 lymphocytes and U1 monocytes, the urinary lysozyme is capable of lysing Micrococcus lysodeikticus. RNase U digests a variety of RNA substrates, including RNA from HIV- 1 infected cells. We also find that lysozyme from chicken egg white, human milk, and human neutrophils and RNase A from bovine pancreas possess activity against HIV-1. Our data permit explanation why the transmission of HIV from mother to fetus is rare, and tears and saliva from AIDS patients are not infectious. These findings may offer new strategies for the treatment of HIV-1 infection. - Angiotensin II, GnRH, receptors, photoaffinity, peptide synthesis, hCG, anti-HIV proteins, lysozyme, ribonucleases