Issue Archive

Regulation of spinach leaf sucrose phosphate synthetase

Wu Yong, Yu Xinjian, Su Liying, Xia Shufang

Shanghai Inst. Plant Physiol., Acad. Sin.

Abstract

Polyacrylamide gel electrophoresis confirmed that at subsaturation concentration of F6P, G6P had a stimulatoy effect on sucrose phosphate synthetase. Both mg super(2+) and Mn super(2+) activated sucrose phosphate synthetase, while EDTA antagonized this activation. We found that NADP inhibited the activity of sucrose phosphate synthetase. The saturation curve of F6P was shown in Fig. 4A. In the presence of NADP, V sub(m) (F6P) decreased and K sub(m) (F6P) increased from 2.5 to 3.8 mmol/L (Fig. 4B), but the Hill coefficient remained unchanged (n=1.3) (Fig. 4A). The saturation curve of UDPG was hyperbolic in shape (Fig. 5A). Inhibition of NADP was noncompetitive with UDPG (Fig. 5B). Concentration of UDPG for 50% maximal activity was 3.8 mmol/L.

Key words: Spinach leaves;Sucrose phosphate synthetase;G6P

Received: 　　Accepted:

Corresponding author: 　　E-mail:

Citing This Article：

Wu Yong, Yu Xinjian, Su Liying, Xia Shufang. Regulation of spinach leaf sucrose phosphate synthetase. Acta Physiol Sin 1991; 43 (2): (in Chinese with English abstract).