STRUCTURE AND BIOSYNTHESIS OF THE XYLOSE-CONTAINING CARBOHYDRATE MOIETY OF RICE ALPHA-AMYLASE

Suspension‐cultured cells of rice secrete α‐amylase into the culture medium. It has been shown that the mature form of the α‐amylase contains xylose‐bearing N‐linked oligosaccharide: (Formula Presented.) and (Formula Presented.) We demonstrate that suspension‐cultured cells of rice secrete α‐amylase containing oligomannose‐type oligosaccharides in the presence of 1‐deoxymannojirimycin or tris(hydroxymethyl)aminomethane. On the other hand, α‐amylase purified from germinated rice seedlings contains several kinds of oligomannose‐type and N‐acetyllactosamine‐type oligosaccharides. The processing pathway of oligosaccharide moieties in rice cells is discussed on the basis of a comparison of these oligosaccharides structures. Copyright © 1990, Wiley Blackwell. All rights reserved