ABSTRACT
The alpha-glucosidase inhibitor acarbose is modified during incubation with cell-free extract from the producing Actinoplanes strain. The formation of this product depends on the presence of ATP. Chromatographic and chemical properties of the purified transformation product indicate the presence of a phosphate ester. The structure is deduced by NMR analysis and shown to be acarbose-7-phosphate.
Subject(s)
Actinomycetales/metabolism , Trisaccharides/biosynthesis , Trisaccharides/chemistry , Trisaccharides/metabolism , Acarbose , Cell Extracts , Enzyme Inhibitors/metabolism , Magnetic Resonance Spectroscopy , Molecular Structure , Phosphates/metabolism , Trisaccharides/isolation & purificationABSTRACT
A phosphotransferase which modifies the alpha-glucosidase inhibitor acarbose by phosphorylation at its 7-position was isolated from the acarbose producer Actinoplanes sp. and purified to homogeneity. The sequence of the first 20 amino acids of the enzyme was determined. The enzyme is an ATP-dependent kinase and shows high specificity for acarbose and some related compounds containing the pseudodisaccharide moiety (acarviosin). The product formed by the enzyme, acarbose-7-phosphate, shows a significant lower inhibitory activity towards disaccharidases than acarbose itself. The acarbose producing organism contains a maltase which is inhibited by acarbose, but to a much lesser extent by acarbose-7-phosphate. The possible role of acarbose 7-phospho-transferase as part of a self-defense mechanism against acarbose in the producing organism is discussed.
Subject(s)
Actinomycetales/enzymology , Phosphotransferases (Alcohol Group Acceptor)/biosynthesis , Phosphotransferases (Alcohol Group Acceptor)/physiology , Phosphotransferases/chemistry , Phosphotransferases/physiology , Actinomycetales/chemistry , Adenosine Triphosphate/metabolism , Amino Acid Sequence , Chromatography, Ion Exchange , Cytoplasm/enzymology , Kinetics , Molecular Sequence Data , Phosphorylation , Phosphotransferases (Alcohol Group Acceptor)/isolation & purification , Substrate SpecificityABSTRACT
Cell free extract of the acarbose producer Actinoplanes sp. catalyzes ATP-dependent phosphorylation of maltose. This was shown by two different assays. The product was purified and its structure determined to be alpha-maltose-1-phosphate by chemical analysis and NMR spectroscopy.
