Copurification of chicken liver soluble thiamine monophosphatase and low molecular weight acid phosphatase

Thiamine monophosphatase (ThMPase) is an enzyme of thiamine metabolism in animals whose molecular nature has still to be elucidated. In this study we have achieved a 714-fold purification of a soluble enzyme possessing ThMPase activity from a chicken liver extract. In addition to ThMPase, acid phosphatase activity was traced during purification. Both activities proved to have coincident elution profiles at all chromatographic steps implying the same enzyme involved. The molecular weight of the enzyme was 18 kDa as estimated by gel filtration. Along with ThMP and p-nitrophenyl phosphate, the purified enzyme was capable of hydrolyzing flavin mononucleotide as well as phosphotyrosine. Subcellular distribution of ThMPase activity was also explored indicating its cytosolic localization. The results of the present work imply the involvement of low molecular weight acid phosphatase in thiamine metabolism in the chicken liver.