Abstract: A method for producing a chondroitin sugar chain comprises reacting a glucuronic acid donor, an N-acetyl galactosamine donor, a sugar receptor and a bacterial cell enzyme which synthesizes chondroitin in the presence of a surfactant. The surfactant is selected from polyoxyethylene octadecyl amine, n-decanoyl-N-methylglucamide, sodium cholate, n-octyl-?-D-thioglucopyranoside, n-nonyl-?-D-thiomaltopyranoside, sucrose monocholate, sucrose monocaprate, and sucrose monolaurate. The chondroitin sugar chain has all the following properties: a weight average molecular weight: 50,000 or more when measured by gel filtration chromatography; it is completely degraded to disaccharides with chondroitinase ABC; and when the sugar chain is decomposed with chondroitinase ABC and the decomposed products are subjected to a disaccharide analysis, substantially all of them correspond to an unsaturated disaccharide unit of chondroitin.

Abstract: A method for producing a chondroitin sugar chain comprises at least the following step: a step of allowing “a glucuronic acid donor”, “an N-acetyl galactosamine donor”, “a sugar receptor” and “a bacterial cell enzyme which synthesizes chondroitin” to coexist in a reaction system in the presence of a surfactant. Here, the surfactant is preferably selected from n-nonyl-?-D-thiomaltopyranoside, sucrose monocaproate and sucrose monolaurate. The chondroitin sugar chain has all the following properties 1) to 3): 1) a weight average molecular weight: 50,000 or more when it is measured by gel filtration chromatography, 2) it is completely degraded to disaccharides with chondroitinase ABC, 3) when the sugar chain is decomposed with chondroitinase ABC and the decomposed products are subjected to a disaccharide analysis, substantially all of them correspond to an unsaturated disaccharide unit of chondroitin.

Abstract: A method for producing a chondroitin (CH) with a desired sugar chain length; a method for producing a fraction containing a CH with a substantially single sugar chain length; etc. There is provided a method for producing a CH with desired sugar chain length, comprising alternately performing the steps (a) allowing a receptor substrate having a glucuronic acid residue at its non-reducing end (when this step is performed after the step (b), sugar chain obtained by the step (b)), an N-acetylgalactosamine donor and an N-acetylgalactosamine transferase to coexist in a reaction system and (b) allowing a receptor substrate having an N-acetylgalactosamine residue at its non-reducing end (when this step is performed after the step (a), sugar chain obtained by the step (a)), a glucuronic acid donor and a glucuronic acid transferase to coexist in a reaction system.