  in carbohydrate chemistry, an anomer is a special type of epimer. it is one of two stereoisomers of a cyclic saccharide that differs only in its configuration at the hemiacetal or hemiketal carbon, also called the anomeric carbon. put simply, the anomeric carbon is the carbonyl carbon (a carbon double-bonded to an oxygen), for example a ketone or aldehyde functional group, in a carbohydrate molecule. anomerization is the process of conversion of one anomer to the other. anomerization is the anomeric analogue of epimerization. ==nomenclature==  two anomers are designated alpha (Î±) or beta (Î²), according to the configurational relationship between the anomeric centre and the anomeric reference atom, hence they are relative stereodescriptors. iupac gold book Î± (alpha), Î² (beta) the anomeric centre in hemiacetals is the anomeric carbon c-1, which is attached to the hemiacetal oxygen (in the ring) and in hemiketals it is carbon c-2, attached to the hemiketal oxygen. in aldohexoses and smaller carbohydrates the anomeric reference atom is the stereocenter that is farthest from anomeric carbon in the ring (the configurational atom, defining the sugar as d or l). in Î±-d-glucopyranose the reference atom is c-5. if in the cyclic fischer projection (see ) the exocyclic oxygen atom at the anomeric centre is cis (on the same side) to the exocyclic oxygen attached to the anomeric reference atom (in the oh group) the anomer is Î±. if the two oxygens are trans (on different sides) the anomer is Î². nomenclature of carbohydrates (recommendations 1996)&nbsp; pdf for cyclic compounds, however, use of the fischer projection is complicated and not common. if the absolute configurations of the anomeric carbon and the reference atom are compared, then both are the same (r,r or s,s) in the Î± anomer and different (r,s or s,r) in the Î² anomer.http://www.ncbi.nlm.nih.gov/books/nbk1955/#_ch2_s4_ originally, the alpha and beta terminology was based on the relative positioning of
Carbohydrate_chemistry Carbohydrates Stereochemistry