Which enzyme preparation contains only alpha amylase and is often preferred for glycogen digestion?

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

Answer: (B)

Glycogen digestion in histology is done to remove glycogen from tissue sections so that PAS staining highlights other carbohydrates without interference. Alpha-amylase is the enzyme that efficiently cleaves internal alpha-1,4 glycosidic bonds in glycogen, breaking it down into smaller dextrins and maltose and thereby removing most of the glycogen signal. When you have a preparation that contains only alpha amylase, you get this targeted, effective digestion without additional activities that could alter other components.

Beta amylase works from the nonreducing ends and tends to produce maltose gradually, which may not fully remove glycogen in the same way and can leave residual byproducts. A mixture labeled malt diastase often contains more than just alpha amylase, introducing variability and potentially less predictable digestion. Protease digests proteins, not carbohydrates, so it would not accomplish glycogen removal.

Thus, the best choice is the enzyme preparation that contains only alpha amylase, providing specific, efficient glycogen digestion for accurate PAS-D outcomes.