The soybean vegetative storage proteins VSP alpha and VSP beta are acid phosphatases active on polyphosphates.

摘要: The soybean vegetative storage protein genes (vspA, and vspB) are regulated in a complex manner developmentally response to external stimuli such as wounding water deficit. proteins accumulate almost one-half the amount of soluble leaf when plants continually depodded have been identified because their abundance pattern expression plant tissues. We shown that purified VSP homodimers (VSP alpha beta) heterodimers alpha/beta) possess acid phosphatase activity (alpha = 0.3-0.4 units/mg; beta 2-4 alpha/beta 7-10 units/mg). Specific activities were determined by monitoring o-carboxyphenyl phosphate (0.7 mM) cleavage at pH 5.5 alpha) or 5.0 0.15 M sodium acetate buffer 25 degrees C. These enzymes active over broad range, maintaining greater than 40% maximal from 4.0 6.5 having 5.0-5.5. They inactivated fluoride, molybdate, heating 70 C for 10 min. phosphatases can liberate Pi several different substrates, including napthyl phosphate, carboxyphenyl sugar-phosphates, glyceraldehyde 3-phosphate, dihydroxyacetone phosphoenolpyruvate, ATP, ADP, PPi, short chain polyphosphates. cleaved polyphosphates most efficiently. Apparent Km Vmax values 42 microM 2.0 mumol/min/mg, 150 4.2 420 4.1 tetrapolyphosphate, pyrophosphate, respectively.