[Serum isoamylases determination. Analytical and critical study of a new method using an inhibitor protein]

A new method for the serum isoamylase assay is studied. Its principle is the use of an inhibitor protein from wheat, mainly active on the salivary type isoamylases. Amylase remaining in the presence of the inhibitor (R) and total amylase (T) are measured and the R/T ratios calculated. The kinetic of the inhibition is studied with various samples of pancreatic juice and saliva, of which the isoenzymatic pattern has been evidenced by electrofocusing. The results show that 80% of the salivary type isoamylases (S) and 20% of those from pancreatic type (P) are inhibited in the operational conditions described. The inhibition is stopped, but not modified, by addition of amylase activity substrate. The analytic study of the kit showed convenient results. The chemical inhibition methodology is compared with a modified Davies' electrophoretic technic on cellulose acetate membrane. The results are shown on a diagram: R/T ratio on the ordinate and total amylasemia on the abscissa. In the middle of the diagram appears an area which corresponds to normal values obtained with 69 healthy subjects from 20 to 30 years old.