An anti-HIV peptide, T22, forms a highly active complex with Zn(II).

T22 ([Tyr5,12, Lys7]-polyphemusin II) has been shown to have strong anti-human immunodeficiency virus (HIV) activity, comparable to that of 3'-azide-2', 3'-dideoxythymidine (AZT). T22 takes an antiparallel beta-sheet structure maintained by two disulfide bridges and contains two antiparallel repeats of Cys-Tyr-Arg-Lys-Cys. As reported herein, fully reduced T22 was found by HPLC and ion spray mass spectrometric analyses to form a complex in a molar ratio of 1:1 with Zn(II) ion at neutral pH in aqueous solution. Complexation of Zn(II) ion to this peptide appears to result in tetracoordinate bonding to sulfur atoms of four Cys residues. We also found that the anti-HIV activity of the T22-Zn(II) complex was fourfold stronger than that of T22.