ACID-PHOSPHATASE OF POTATO-TUBERS (SOLANUM-TUBEROSUM-L) - PURIFICATION, PROPERTIES, SUGAR AND AMINO-ACID-COMPOSITION

  • 1 January 1982
    • journal article
    • research article
    • Vol. 29  (3-4) , 321-330
Abstract
Acid phosphatase (AcPase) from potato tubers was purified by tannic acid fractionation, DEAE-cellulose chromatography, filtration on Bio-Gel P-150 and affinity chromatography on Con [concanavalin] A-Sepharose. The enzyme was purified 260-fold and was electrophoretically homogeneous; its MW was .apprx. 69,000. The carbohydrate component accounts for 16.6% of the total enzyme weight and includes mannose (5.6%), rhamnose (3.4%), glucose (2.5%), galactose (1.5%) and glucosamine (3.6%). In the amino acid composition aspartic acid, glutamic acid, serine and glycine account for 37.7% of total amino acid residues. Optimum pH is at 5.0-5.3. The enzyme activity was reduced by half after 30 min incubation at 60.degree. C, and was fully abolished after 2 h incubation at 70.degree. C. The enzyme is a nonspecific phosphomonoesterase; aromatic phosphomonoesters and PPi can serve as substrates. Apparent Km values were 1.25 and 40 mM for p-nitrophenylphosphate and PPi, respectively. The enzyme is inhibited by MoO42-, Zn2+, Hg2+ and urea. Inhibition caused by urea was reversible at urea concentration below 9 M.