Intrinsic activity of precursor forms of HIV-1 proteinase.

The wild-type -Phe*Pro- bond located at the N-terminus of the mature aspartic proteinase of HIV-1 was replaced by -Ile-Pro- or -Val-Pro-. By this means, processing at this cleavage junction was prevented and so, extended or precursor forms of HIV-proteinase were generated. These constructs were expressed in Escherichia coli, purified therefrom, and their specificity, activity at different pH values and susceptibility to the potent inhibitor, Ro31-8959, was assessed.

The Sequencing, Synthesis, and Biological Actions of an ANP-Like Peptide Isolated from the Brain of the Killifish Fundulus heteroclitus.

We have extracted, purified, and sequenced an ANP-like peptide from the killifish. The peptide was extracted from whole brains with acidic acetone, and the aqueous phase remaining after evaporation of the acetone was subjected directly to HPLC. A pure peak was obtained after three successive HPLC steps.

Isolation, characterization, and amino acid sequence of a polypeptide neurotoxin occurring in the sea anemone Stichodactyla helianthus.

An aqueous exudate collected from frozen and thawed bodies of a Caribbean sea anemone, Stichodactyla (formerly Stoichactis) helianthus, contained a polypeptide neurotoxin (Sh I) selectively toxic to crustaceans. The polypeptide was purified by G-50 Sephadex, phosphocellulose, and sulfopropyl-Sephadex chromatography and shown to have a molecular size of 5200 daltons and a pI of 8.3.

A systematic series of synthetic chromophoric substrates for aspartic proteinases.

The hydrolysis of the chromogenic peptide Pro-Thr-Glu-Phe-Phe(4-NO2)-Arg-Leu at the Phe-Phe(4-NO2) bond by nine aspartic proteinases of animal origin and seven enzymes from micro-organisms is described [Phe(4-NO2) is p-nitro-L-phenylalanine]. A further series of six peptides was synthesized in which the residue in the P3 position was systematically varied from hydrophobic to hydrophilic. The Phe-Phe(4-NO2) bond was established as the only peptide bond cleaved, and kinetic constants were obtained for the hydrolysis of these peptide substrates by a representative selection of aspartic proteinases of animal and microbial origin.