A novel acid phosphatase from cactus (Opuntia megacantha Salm-Dyck) cladodes: Purification and biochemical characterization of the enzyme

Acid phosphatase (ACP) plays an important role in regulating phosphate nutrition in plants. Herein, for the first time, a novel ACP fromOpuntiamegacantha Salm-Dyck cladodeswas purified to homogeneity and biochemically characterized. Specific activity of 8.78U/mgwas obtained with 11.29-fold purification and 15% yield. ACPwas purified as monomer with molecular weight of 44 kDa as determined by SDS-PAGE under denaturing and nondenaturing conditions. Optimum pH and temperature for ACP activity was 5.5 and 60 degrees C, respectively. Thermodynamic parameters (E-a, Delta H, Delta G and Delta S) were also determined. ACP activitywas stimulated by Ca2+, strongly inhibited by Cu2+ and Fe3+, and moderately inhibited by Mg2+ and Zn2+. Br-, CN-, F-, I- and N-3(-) weakly inhibited ACP activity, where more than 70% of enzyme activity was remained at 5 mM. In addition, effect of beta-ME, Cys, DTT, EDTA, H2O2, PMSF, SDS and TX-100 on ACP activity was investigated. k(m), V-max, k(cat) and k(cat)/k(m) of ACP for p-NPP were found to be 0.09 mM, 2.75 U/mL, 9.60 s(-1) and 106.67 s(-1) mM(-1), respectively. The biochemical properties of ACP from Opuntia megacantha Salm-Dyck cladodes provide novel features with other plant ACPs and basic knowledge of ACP in Opuntia species. (C) 2020 Elsevier B.V. All rights reserved.