Steric Relationships of Aldopentoses and Aldohexoses

[摘要] The relationships between the aldopentoses and aldohexoses, based on possible synthetic paths in the laboratory, embodied in the nomenclature, and shown in the straight chain formulas used in elementary presentations of sugar chemistry, do not allow easy visualization of the actual spatial relationships of the ring forms, although the (pyranose) ring forms are probably the ones mainly important in serologic reactions. For example, the close similarity in specific inhibitory power of l-arabinose and d-galactose for various plant agglutinins (lectins) (1, 2), or the similarity of action of l-mannose and d-gulose, would hardly be predicted from the straight chain formulas. From these formulas one might conclude that the pentose most resembling d-glucose in its serologic behavior would be d-arabinose; actually it is d-xylose. The hexoses corresponding to d-arabinose are the “unnatural” sugars, d-altrose and l-galactose. Modern textbooks of biochemistry make considerable use of the ring formulas, but apparently none of them point out these and other consequences of the actual structures, and there would seem to be room for a brief discussion of the subject.

[学科分类] 生物科学（综合）