Sucrase catalyzes its substrate (sucrose) to produce glucose, which produces hydrogen peroXide under the action of glucose oXidase. Hydrogen peroXide reacts with chromogenic agent to produce red substance, which has a strong absorption peak at 505 nm. In a certain concentration range, It's absorbance is proportional to glucose concentration. Therefore, the actIVIty of sucrase can be calculated by measuring the OD value at 505 nm.