(R)-glycerate + D-glucose => (2R)-2-O-(alpha-D-glucopyranosyl)-glycerate + H2O
(r)-glycerate + d-glucose => (2r)-2-o-(alpha-d-glucopyranosyl)-glycerate + h2o
(R)-glycerate + D-glucose => (2R)-2-O-(alpha-D-glucopyranosyl)-glycerate + H2O
(r)-glycerate + d-glucose => (2r)-2-o-(alpha-d-glucopyranosyl)-glycerate + h2o