3-Amylases crystalline, properties

It is worth while noting, however, that Thomas, Whelan, and Peat found that sweet potato, crystalline jS-amylase or soybean, purified /3-amyl-ase will cleave pure amylose only 70% to completion. Cruder soybean preparations contain an additional factor ( Z enzyme ) which when added to the purified amylase will allow hydrolysis of the amylose to proceed to completion. The Z enzyme has been purified and found to have all the properties of a jS-glucosidase, and, in fact, emulsin will replace it. Consequently it appears that amylose contains one or more /3-linked glucose residues in the chain, or more likely attached to the chain at the free 2, 3, 5, or 6 position of an intra-chain glucose residue. Since it would probably take only one such /8-linked residue per chain to interrupt the progress of /3-amylase, it is not imusual that methylation studies have not detected it. The structure outlined previously for amylose may be modified somewhat to include these observations. 

---