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α-amylase Activity Measurement Method
An α-amylase solution (such as saliva) is added to a solution in which starch has been
dissolved inside a test tube. If an iodine solution is immediately added to this, before any
of the starch has been broken down, the starch will react with the iodine and produce a
blue-violet color. However, as time passes, the starch is broken down by the α-amylase,
and the color steadily changes (blue-violet violet red orange pale orange). Even-
tually, when all the starch has been broken down, the solution will become colorless. The
enzyme activity of α-amylase can be measured by using a spectrophotometer to quantify
the appearance of its color as a numeric value.
Color reaction
Starch When starch is present, it’s colored
blue-violet when it reacts with
iodine-potassium iodide.
α-amylase Iodine Reaction As the starch is broken down
solution is progresses by α-amylase, the color
added. steadily changes from blue-
violet to violet to red to
orange to pale orange and
finally becomes colorless.
α-amylase activity
measurement method
Molecular Biology and the Biochemistry of Nucleic Acids 237
