FIELD: medicine, oncology, molecular biology. SUBSTANCE: invention describes the improved method of chemotherapy of malignant mammalian cells showing absolute requirement in methionine but devoiding of activity of methylthioadenosine phosphorylase. Method involves detection of methylthioadenosine phosphorylase-negative cells in mammal body, administration of methionine-γ-lyase in sufficient amount to decrease the volume of methylthioadenosine phosphorylase-negative cells in mammal body and combined administration of methylthioadenosine in sufficient amount for constant availability of methionine for nonmalignant cells of mammal. Invention proposes also catalytically active polypeptide of recombinant methylthio-adenosine phosphorylase and polynucleotide encoding this polypeptide. EFFECT: broadened arsenal of agents for control of malignant cells. 21 cl, 2 tbl, 4 dwg, 5 ex
