Soluble Starch Synthase (SSS, EC 2.4.1.21) usually present in the free matrix in the plastid matrix, which
catalyzes the elongation of the starch chain, mainly responsible for the synthesis of amylopectin.
SSS catalyzes the reaction of ADPG with starch primer (glucan), transfers glucose molecules to starch
primers, and simultaneously produces ADP. Add pyruvate kinase, hexokinase and 6-phosphate glucose
dehydrogenase to the reaction system. These enzymes in turn catalyze NADP+ reduction to NADPH, the
amount of NADPH produced is proportional to the amount of ADP produced in the previous step reaction,
and the SSS activity can be calculated by measuring the increase of NADPH at 340 nm.
Required but not provided:
Spectrophotometer/microplate reader, water bath, desk centrifuge, transferpettor, micro quartz cuvette/96
well UV plate, mortar/homogenizer, ice and distilled water.
Protocol:
I. Sample Preparation.
Add 1 mL Extract solution to 0.1 g tissue, homogenate on ice. 10000 g centrifuge at 4℃ for 10 min. Take
the supernatant on ice for test.
II. Determination
