Identification of the characteristic amino-acid sequence for human α-amylase encoded by the AMY2B gene

Abstract

Human salivary and pancreatic α-amylases (HSA and HPA) are the respective gene products of the AMY1 and AMY2A genes. AMY2B is a newly found human α-amylase gene. The presence of the AMY2B gene product (HXA) in the urine of healthy humans was examined. A mixture of α-amylases that seemed to contain HXA, judging from the substrate specificity, was purified from urine of healthy volunteers by affinity adsorption on starch and then by ion-exchange chromatography. The mixture was reduced and S-alkylated, and the product was digested with trypsin. The digest was separated by reversed-phase HPLC. LVGLLDLALEKDYVR and LVGLLDLALEK, which were found in the digest, are peptids of HXA, but not of HSA and HPA. The detection of these characteristic peptides of HXA demonstrates the presence of HXA in the urine of healthy humans.