Salivary Alpha-Amylase
Definition
An enzyme (EC 3.2.1.1) secreted by the parotid, submandibular, and sublingual glands. Digests starch and is present in saliva at concentrations of 0.1 to 0.5 mg/mL. The principal immunological target for saliva identification.
- Enzyme class
- EC 3.2.1.1
- Source glands
- Parotid, submandibular, sublingual
- Typical saliva concentration
- 0.1 to 0.5 mg/mL
- Forensic role
- Primary immunological target for saliva ID
Common questions
Why is amylase concentration useful for identifying saliva rather than just detecting its presence?+
Saliva carries alpha-amylase at levels well above most other body fluids, so a quantitative or semi-quantitative test that shows a high concentration supports a saliva source specifically, rather than only confirming that some biological fluid is present.
Does a positive amylase test alone confirm saliva to a courtroom standard?+
Amylase is present at lower levels in some other fluids and secretions, so a positive result is treated as presumptive evidence that supports, but does not by itself conclusively prove, a saliva source; confirmatory or corroborating tests are typically sought.
What sample types is salivary alpha-amylase commonly tested on in casework?+
It is commonly tested on swabs from bite marks, cigarette butts, envelope flaps, stamps, drinking vessels, and clothing where a saliva stain is suspected, since these surfaces frequently carry trace saliva deposits.
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