A couple of posts ago Steve from the excellent Breadcetera ** site asked if the structures in the link…
SB “If I’m not mistaken, the structures for the 1,4-glycosidic and 1,6-glycosidic linkages shown here are incorrect. There appear to be extraneous carbon atoms on either side of the oxygen atom of the linkage”.
The use of the projection used in the Cheng link, and below, to describe the structure of polysaccharides makes the interesting, and as a I think about more after Breadcetera’s prompting, rather glib, assumption that folks won’t think that the corner between C1 and the glycosidic O and then the corner between the O atom and the next C4 are not actually C atoms, as the corners in the ring structure infer just that; those corners ARE meant to represent C atoms.
Look at my freehand version of a section of starch acetate to see.
The representations here at http://www.chemistryexplained.com [ http://www.chemistryexplained.com/Co-Di/Disaccharides.html ] might clarify this issue. The best one to look at with respect to starch is the maltose molecule in Figure 2. In the chemistry explained version all of the H and O atoms are also indicated
So this changes the above shorthand representation to this.
Hope this clarifies – Cheers, Andrew
**Breadcetera has also been named as one of the 50 Best Blogs for a Complete Culinary Education. Where they note that “Steve is an organic chemist turned bread baker, so you know he gets it right“.