Is it possible a single glycosyltransefrase can have inversion as well as retention properties with a single acceptor substrate? Are there any published references?
Until recently, the accepted answer would have been "No, these enzymes are specific for either inversion or retention of the donor's anomeric configuration." However, one recently published paper suggests that at least one complex glycosyltransferase may be capable of both. You might be interested in reading :
Giant mimivirus R707 encodes a glycogenin paralog polymerizing glucose through alpha and beta glycosidic linkages
Anna J Rommel, Andreas J Hülsmeier, Simon Jurt, Thierry Hennet