ACARBOSE 7-PHOSPHOTRANSFERASE FROM ACTINOPLANES SP - PURIFICATION, PROPERTIES, AND POSSIBLE PHYSIOLOGICAL-FUNCTION

A phosphotransferase which modifies the alpha-glucosidase inhibitor ac arbose by phosphorylation at its 7-position was isolated from the acar bose producer Actinoplanes sp. and purified to homogeneity. The sequen ce of the first 20 amino acids of the enzyme was determined. The enzym e is an ATP-dependent kinase and shows high specificity for acarbose a nd some related compounds containing the pseudodisaccharide moiety (ac arviosin). The product formed by the enzyme, acarbose-7-phosphate, sho ws a significant lower inhibitory activity towards disaccharidases tha n acarbose itself. The acarbose producing organism contains a maltase which is inhibited by acarbose, but to a much lesser extent by acarbos e-7-phosphate. The possible role of acarbose 7-phosphotransferase as p art dr a self-defense mechanism against acarbose in the producing orga nism is discussed.