Characterization of almond alpha-mannosidase and its application for structure analysis of sugar chain.

Almond alpha-mannosidase was purified by separation on columns of DEAE-Sephadex A50 and hydroxyapatite, and characterized. Its optimum pH was approximately 3.8. It was also shown to be stable from pH 6 to 8. Its activity was stable up to 60 degrees C. The thermostability of almond alpha-mannosidase at 73 degrees C appeared to be superior to that of jack bean a-mannosidase. We examined the substrate specificity of the former toward high-mannose-type N-glycan Man9GlcNAc2, and showed that the deduced trimming pathway was more diverse than that of the latter. We could use almond alpha-mannosidase as well as jack bean alpha-mannosidase for analysis of sugar chain structures.