Invertase (Ivr) catalyzes the irreversible decomposition of sucrose into fructose and glucose, which is one
of the key enzymes in sucrose metabolism of higher plants. According to the optimal pH, Ivr can be
divided into two types: acid invertase (AI) and neutral invertase (Ni).
AI (EC 3.2.1.26) mainly exists in cell vacuole or free space, and the optimal pH is 4.5-5.0 (acid). It can
regulate the utilization of sucrose in vacuole and the accumulation of sugar in fruit by degrading sucrose in
vacuole.
AI catalyzes the degradation of sucrose to produce reducing sugar, and further reacts with 3,5-
dinitrosalicylic acid to form brownish red amino compound, which has a characteristic light absorption at
540 nm. the increase rate of light absorption at 540 nm in a certain range is in direct proportion to AI
activity.
Reagents and Equipment Required but Not Provided
Spectrophotometer, desktop centrifuge, water-bath, adjustable pipette, 1 mL glass cuvette,
mortar/homogenizer, ice and distilled water.
