Histologists often prefer an enzyme preparation that contains only alpha amylase for glycogen digestion. Which preparation is this?

• A. Malt diastase
• B. Alpha amylase
• C. Beta amylase
• D. Cellulase

Answer: (B)

Glycogen digestion in histology relies on an enzyme that can efficiently break down the branched polymer by targeting the internal α-1,4 glycosidic bonds. Alpha amylase is an endoenzyme that does just that, cleaving these bonds throughout the molecule to produce small dextrins and sugars quickly and predictably. Because the glycogen structure includes branches at α-1,6 linkages, using a preparation that contains only alpha amylase avoids additional enzymatic activities and byproducts that could complicate digestion or staining. A pure alpha amylase preparation provides consistent and complete digestion of the linear portions of glycogen, which is why it’s preferred.

Malt diastase, while commonly associated with amylase activity from malt, is not purely alpha amylase and can include other activities, making the digestion less predictable. Beta amylase acts from non-reducing ends and stops at branch points, yielding more maltose and incomplete digestion of glycogen. Cellulase digests cellulose, not glycogen, so it would not accomplish the goal.