水稻幼苗根细胞质膜和液泡膜微囊Ca^(2+)-ATP酶的特性

Characteristics of Ca^(2+)-ATPase of Plasma Membrane and Tonoplast Membrane Vesicles from Roots of Rice Seedlings

水稻幼苗根质膜和液泡膜Ca2+-ATP酶对ATP的Km值分别为7.1和4.5μmol.L-1;反应的最适pH分别为8.0和7.0。两者活性均受Na3VO4和曙红B(EB)抑制;CPZ抑制质膜Ca2+-ATP酶活性,但促进液泡膜Ca2+-ATP酶活性。30mmol.L-1CaCl2浸种和CaCl2浸种结合低温锻炼预处理,均可提高此酶的活性和冷稳定性。

Plasma and tonoplast membrane-enriched vesicles were prepared from rice seedling root by DextranT70 gradient centrifugation. Ca2+-ATPase of both vesicles were identified. The Km values for ATP of Ca2+-ATPase of plasma membrane and tonoplast membrane vesicles are 7.1 and 4.5 μmol.L-1 respectively, and theoptimum pH values of the two vesicles were 8.0 and 7.0, respectively. The enzyme activities of both vesicleswere inhibited by Na3VO4 and erythrosin B (EB).The activity from plasma membrane was inhibited by chlor-promazine (CPZ), but the activity from tonoplast membrane was promoted by CPZ. However, the enzymeacitivties and its cold stability of both vesicles were improved by rice seed-submerged in CaCl2 treatment orseedling-cold-hardened treatment following seed-submerged in CaCl2 treatment.