| abstract |
A process for obtaining N-acetylneuraminic acid from N-acetylglucosamine is disclosed. The process is carried out in a reactor which contains both N-acylglucosamine-2-epimerase (E.C. 5.1.3.8) which isomerizes GlcNac into ManNac, and N-acetylneuraminic acid pyruvate lyase (E.C. 4.1.3.3) which catalyzes the reaction of the resulting ManNac with pyruvic acid to give Neu5Ac. GlcNAc and Pyr are fed into the reactor and Neu5Ac is obtained in the outflow. The process is preferably carried out continuously and in particular in an enzyme membrane reactor at pH 7.5 and 25 DEG C., especially using residence times of 0.2 to 10 h, and with an excess of GlcNac in comparison with Pyr which is subsequently added if necessary. Epimerase and lyase are preferably present in the reactor in a ratio of activities which is equivalent to the reciprocal value of the quotient of the conversion rates. |