Carbohydrates: characteristic chemical monosaccharides

Recent work by Calvin and co-workers and by Horecker et al. have demonstrated the importance of sedoheptulose in the photosynthetic cycle of the carbohydrates as being a transitory intermediate in the regeneration of D-erythropentulose, the monosaccharide involved in the fixation of carbon dioxide . This sugar also plays a part in animal carbohydrate metabolism. Its most characteristic chemical property is its ready conversion into sedoheptulosan.(2,7-anhydro-j8-D-altroheptulopyranose (LVII). 

Fig. 1 also may be used to note some general characteristics of C spectra of carbohydrate polymers ( -11) Chemical shifts of anomeric carbons (C-l), in the region of 100-110 p.p.m., are typically well separated from other signals. As compared with C-l of the related monosaccharides (12-15)j the anomeric carbon is strongly deshielded (commonly by 7-10 p.p.m.) through glycoside formation (9)> i.e., by the change from 0-H to an 0-C bond. 

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