Notes: 4-Nitrophenyl α-D-glucopyranoside is a colorimetric substrate for α-glucosidases.{62743} Upon enzymatic cleavage, p-nitrophenol is released, which can be quantified by colorimetric detection at 405 nm as a measure of α-glucosidase activity. 4-Nitrophenyl α-D-glucopyranoside has also been used as a colorimetric substrate for glucansucrases.{62744}