Abstract: The enzyme .gamma.-glutamylcysteine transferase is disclosed. .gamma.-Glutamylcysteine transferase catalyzes the transfer of .gamma.-glutamylcysteine or .gamma.-glutamycysteine S-derivates and is produced by extracting plant material from the families of Apocynaceae, Asciepladaceae, Berberidaceae, Chenopodiaceae, Caryophyllacea, Dioscoreaceae, Fumariaceae, Graminaceae, Iridaceae, Leguminosae, Menispermaceae, Papveraceae, Ranunculaceae, Rosaceae, Rubiaceae, Solanaceae or Violaceae, or tissue of algea (Phycophyta) or fungi (Mycophyta).

Abstract: Disclosed are peptides which have the following amino acid sequence:(.gamma.-Glu-Cys).sub.n -.beta.-Alan being an integer from 2 to 11;.gamma.-Glu represents .gamma.-glutamic acid;Cys represents cysteine; and.beta.-Ala represents .beta.-alanine.A process for the preparation of these peptides is disclosed as well as processes for their use for the maintenance of hemeostasis in physiological systems, the diagnosis of tumors, and the removal of heavy metals from a chemical or physiological system which has been contaminated with heavy metal.

Abstract: A high-cysteine polypeptide having an amino acid sequence of the formula:-(.gamma.-Glu-Cys).sub.n -Glyin which,n is an integer from 4 to 7,.gamma.-Glu represents .gamma.-glutamic acid,Cys represents cysteine, andGly represents glycine,for use in pharmaceutical preparations for treating acute and chronic heavy metal poisoning. Alternatively, the polypeptides may be employed in the treatment of metal deficiency phenomena or for maintaining the homeostasis in physiological systems with respect to such metals as iron or zinc. Processes for producing the polypeptides of the invention are also disclosed.