Glycerate kinase from leaves of C3 plants

D-Glycerate-3-kinase (EC 2.7.1.31) in six C3 species, including dicots (Pisum sativum, Spinacea oleracea, Antirrhinum majus) and monocots (Secale cereale, Hordeum vulgare, Avena sativa), ranged in activity from 44 to 353 mumol X mg chl-1 X h-1. Studies with protoplast extracts of these species indicate that the enzyme is localized in the chloroplasts. Glycerate kinase was partially purified from Secale (rye, 288-fold) and Pisum (pea, 252-fold) chloroplasts by DEAE-cellulose chromatography, sucrose gradient centrifugation, and chromatofocusing. The enzymes from both species showed similar physical (Mr = 41,000, pI = 4.6-4.7) and kinetic (Km ATP = 655 to 692 microM, Km D-glycerate = 180-188 microM) properties. Activity of the enzyme was essentially insensitive to variations in assay pH from 6.4 to 9.0 and to energy charge variations from 0.4 to 1.0. Rye glycerate kinase was able to utilize UTP and GTP but less effectively than ATP. Neither ADP nor pyrophosphate served as an energy source. Mn2+, Co2+, Ca2+, and Sr2+ could function as metal cofactors, although to a lesser extent than Mg2+. Millimolar levels of sulfate were found to significantly inhibit the enzyme while similar concentrations of other anions (Cl-, NO-3, NO-2, and acetate) had little or no effect.