Exo-acting 3-amylases

The (3-amylases catalyze starch hydrolysis by a mechanism that gives inversion of configuration at the anomeric center. All known (3-amylases have an exo-mechanism and act on the non-reducing ends of starch polymer chains or starch polymer-derived chains. There are two general classes of (3-amylases, those that are classically known as (3-amylases and produce (3-maltose, and those that are known as glucoamylases and produce (3-D-glucose. 

The major enzymes that have been used for studying structures of starch polymers and fragments from them are the endo-acting a-amylases, the exo-acting glucoamylase and (3-amylases, and the debranching enzymes, isoamylases and pullulanases. These enzymes have varied and diverse specificities that have been extensively studied (see previous sections). 

---