Alpha-Amylase (Salivary)
Definition
An enzyme encoded by the AMY1 gene and secreted by the parotid, submandibular, and sublingual glands. It cleaves starch at alpha-1,4-glycosidic bonds and is present in saliva at concentrations orders of magnitude above most other body fluids.
- Gene
- AMY1
- Secreting glands
- Parotid, submandibular, sublingual
- Bond cleaved
- Alpha-1,4-glycosidic bonds in starch
- Forensic marker role
- Presumptive saliva indicator
Common questions
Why does saliva contain so much more amylase than most other fluids?+
The three major salivary glands secrete amylase continuously as part of digestion, so its baseline concentration in saliva sits far above incidental levels found in blood or other secretions, which is why elevated amylase is used as a screening indicator rather than appearing by chance.
Does the AMY1 gene copy number matter for forensic interpretation?+
AMY1 copy number varies between individuals and affects how much amylase a person's saliva contains, but this variation affects sensitivity of detection rather than the identification itself, since even a low-copy individual's saliva still greatly exceeds non-salivary background levels.
Related terms
- Double-Swab Technique
- A collection method for dried biological stains in which a moistened swab rehydrates and lifts the stain from the surface, followed immediately...
- Isoforms of Amylase
- The human genome encodes multiple AMY loci. AMY1 products are expressed in saliva; AMY2 products are expressed in the pancreas. The two...
- Phadebas Test
- A colorimetric presumptive test for alpha-amylase activity. Phadebas tablets contain a blue-dyed insoluble starch; amylase releases soluble blue dye that is measured...
- Presumptive vs Confirmatory Testing
- Presumptive tests (Phadebas) give rapid screening results but have cross-reactants; they justify further analysis. Confirmatory or highly specific tests (RSID-Saliva, mRNA analysis)...
- RSID-Saliva
- Rapid Stain Identification of Saliva. An immunochromatographic lateral-flow assay using monoclonal antibodies specific to human salivary amylase. More specific than Phadebas, with...