Further study of human salivary alpha-amylase polymorphism

Genetic variants of salivary alpha-amylase were studied using isoelectric focusing in a pH gradient of 6-8 and silver staining methods. Five phenotypes which were tentatively named Amy1 N, Amy1 SN, Amy1 V1N, Amy1 V2SN and Amy1 V3N were detected. The phenotype frequencies in 371 unrelated Japanese were: Amy1 N = 94.33, Amy1 SN = 2.43, Amy1 V1N = 0.54, Amy1 V2SN = 0.27 and Amy1 V3N = 2.43%, respectively. Although variant bands of Amy1 V1N were detected by immunoblotting method using anti-human salivary amylase, those bands were not stained by starch-iodine method for the detection of amylase activity. This suggested that a mutation was occurred in the region of amylase molecule which showed the activity. Amy1 V2SN comprised the production of three Amy1 genes and indicated the duplication of Amy1 gene. The individuals showing Amy1 V3N phenotype accorded with those showing amylase variant by PAGE.