Molecular weight and amino acid composition of Macaca irus parotid alpha-amylase

abstract – Parotid alpha-amylase from Macaca irus monkey was obtained by cultivation of glandular tissue in vitro. Gel filtration of the unpurified amylase on Sephadex® and Bio-Gel® columns, using reference proteins, showed a molecular weight of the amylase below 18,000, whereas ultracentrifugation of the crystalline enzyme indicated about 54,000. These values were consistent with the corresponding human amylase, the discrepancy in molecular weight being explained by charge phenomena between the gel matrix and the amylase molecules, causing retardation on the gel filtration columns. The minimum molecular weight according to the amino acid composition was determined to 28,000. Amino acid analysis of the crystalline Macaca irus parotid alpha-amylase showed characteristics very similar to the human parotid amylase, with high amounts of aspartic acid and glycine, and small amounts of the sulfur-containing amino acids. No hexosamines were found. Purification of the parotid amylase from Cercopithecus aethiops monkey indicated different molecular parameters. These findings support the belief that the Macaca irus monkey is well suited as an experimental animal in dental research.