Purification and partial characterization of alpha-mannosidase from Trypanosoma rangeli

An alpha-mannosidase from Trypanosoma rangeli was partially purified by a protocol involving solubilization using lysis buffer followed by chromatography on diethylaminoethyl (DEAE)-cellulose and Sephadex 100 columns. The enzyme has a molecular weight of 45 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and of 90 kDa as determined by gel filtration. The purified T. rangeli alpha-mannosidase has a pH optimum ranging between 5 and 6 and a temperature optimum of 37 degrees C. It has activation energy of 8.15 x 10(2) J mol(-1) K(-1). The enzyme has a Michaelis constant (Km) of 99 microM for the 4-methylumbelliferyl-alpha-D-mannopyranoside substrate (MU-alpha-mann). It is strongly inhibited by swainsonine [inhibition constant (Ki) 0.048 microM] and is moderately inhibited by mannose and alpha-D-methylmannopyranoside. The enzyme activity is decreased in the presence of 1 mM Ca2+, Co2+, Cu2+, Fe2+, Fe3+, Hg2+, Mg2+, and Mn2+.