Limit dextrinase was prepared from malted barley with a high degree of
purity and a yield of 17% of the total limit dextrinase. Enzyme activ
ity was not affected by dithiothreitol, indicating that limit dextrina
se is not a sulfhydryl enzyme. However, enzyme levels were enhanced si
gnificantly in the presence of proteins such as bovine serum albumen (
BSA); the pH optimum of the enzyme was also affected by BSA. The enzym
e was inhibited strongly by low levels (100 mu g/ml) of beta-cyclodext
rin. Low levels of enzyme activity were present in barley, but enzyme
levels increased rapidly during germination in a manner similar to tha
t of cu-amylase. A significant proportion of malt limit dextrinase was
present in malt extracts in a soluble but inactive form. Conditions w
ere established for the complete extraction of active limit dextrinase
from malt and from barley germinated for varying periods of time (one
to eight days).