Construction of saturated odd- and even-numbered hyaluronan oligosaccharide building block library

Hyaluronic acid (HA) and its oligosaccharides (o-HAs) have been receiving much attention as medical treatments. Even-numbered o-HAs with two different reducing ends (HA(20)(AN) and HA(2n)(NA), n = 1, 2, 3...) can be prepared using bovine testicular hyaluronidase (BTH) and leech hyaluronidase (LHase) respectively, while preparation of odd-numbered o-HAs (HA(2n+1)(AA) and HA(2n+1)(NN), n = 1, 2, 3...) is relatively difficult. A new enzymatic method was developed to prepare odd-numbered o-HAs in this study, taking advantage of differences in the degradation of glycosidic linkages by BTH and LHase. Through quantitative analysis of the yield of even-numbered o-HAs, a dynamic model for LHase hydrolysis was established, providing optimal preparation conditions for HA(2n)(NA) (n = 1-5). Then HA(2n)(NA) (n = 2-5) was further degraded by BTH to produce odd-numbered o-HAs. The above o-HAs were separated and purified by combining high-performance Q-Sepharose ion-exchange (Q HP) and size exclusion column chromatography steps.