Carbohydrates conjugated with 2-chloro-4-nitrophenyl (CNP) serve as chromogenic substrates in assays for enzymes that release CNP from the conjugated carbohydrate.{27183,27182} For example, CNP-B-D-maltoheptaoside and CNP-a-maltotrioside are chromogenic substrates for a-amylase.{27181,27186} 2-Chloro-4-nitrophenyl-a-D-glucopyranoside is a conjugate of CNP and a-D-glucose. The related conjugate between CNP and B-D-glucose, 2-chloro-4-nitrophenyl B-D-glucopyranoside, is used as a chromogenic substrate for glycosyltransferases.{27185,27184} This product is a chromogenic substrate for enzymes that target the linkage between CNP and a-D-glucose.