Sucrose invertase (Invertase, Inv) irreversibly catalyzes sucrose to form glucose and fructose, which plays
an important role in plant sucrose metabolism. According to the optimum pH, Inv can be divided into acid
invertase (AI) and neutral invertase (NI). Among them, AI can be divided into soluble acid invertase (SAI)
and cell wall-bound acid Invertase (CWI) according to the difference of subcellular localization. CWI is
bound to the cell wall in the form of ionic bonds, and plays an important role in sucrose unloading, sucrose
extracellular transport, plant growth and development, and resistance to various stresses in the phloem.
CWI catalyzes the degradation of sucrose to produce reducing sugar. The reducing sugar reacts with 3,5-
dinitrosalicylic acid to produce a brown-red substance with a characteristic absorption peak at 540 nm. The
CWI activity can be calculated by measuring the change in absorbance at 540 nm.
Required but Not Provided:
Spectrophotometer/microplate reader, desk centrifuge, water-bath, transferpettor, mortar/homogenizer,
micro glass cuvette/ 96-well flat-bottom plate, ice, EP tube and distilled water.
Protocol
I. Preparation:
Tissue: According to the quality (g): extract solution I (mL)=1: 5~10 (recommend to weigh about 0.1 g,
add 1 mL of extract solution I) to add the extract solution I, homogenize on an ice bath, centrifuge at
12000g and 4℃ for 10 min, discard the supernatant and leave the pellet. Add 1 mL of distilled water to the
pellet and mix thoroughly with shaking, centrifuge at 12000 g and 4℃ for 10 min, discard the supernatant
and leave the pellet; add 1 mL of extract solution II to the pellet and thoroughly mix, extract for 15 h at
