Doris J. Stiefel

Preparation and some properties of human pancreatic amylase including a comparison with human parotid amylase

A method for the preparation of α-amylase (α-1,4-glucan-4-glucanohydrolase, EC 3.2.1.1) from human pancreatic juice is described. Procedures utilizing (NH4)2SO4 fractionation, ion-exchange chromatography and gel filtration resulted in an amylase preparation of high purity (2085 maltose units per mg) and good yield (59%). Electrophoresis on polyacrylamide disc gels yielded characteristic isoenzyme patterns with up to six bands on anionic gels. Comparisons with crystalline human parotid amylase indicated that the two principal human amylases are closely related enzymes but also exhibit organ specific variation. The two enzymes yielded the same amino acid composition and similar but not identical peptide maps. Each appears to consist of a single polypeptide chain. At neutral pH both amylases exhibited the same action pattern. Differences were noted in molecular weight, gel filtration profile, carbohydrate content and the accessibility of reactive sulfhydryl groups. A both high and low temperature extremes pancreatic amylase was more labile than the parotid enzyme. A less compact configuration is indicated for pancreatic amylase. A relationship is postulated between the number of sulfhydryl groups in the amylase molecule and the mode of action. Amylases possessing 1 sulfhydryl group, namely those from human pancreatic juice, human parotid saliva and rat parotid saliva, exhibited the same type of action pattern whereas porcine pancreatic amylase, with 2 sulfhydryls, was different.

Characteristics of an In Vitro Dental Pellicle

Dental pellicle was formed in vitro after two-hour incubation of extracted human molars in parotid saliva. Control teeth were incubated in distilled water. Electropherograms of proteins subsequently eluted from the teeth indicated selective salivary adsorption and desorption. In addition, extra-salivary pellicle constituents, comprising albumin and alkaline phosphatase, were identified.