An appraisal of methods for serum amylase determination

Amylase Determination Using Insoluble Substrates

Three insoluble substrate amylase methods are compared. There is good correlation between the three procedures and with a saccharogenic procedure. Correlation with the starch-iodine method of Caraway is poor. Insoluble substrate methods are very suitable for the routine determination of amylase activity, and their advantages compared with saccharogenic and starch-iodine procedures are detailed.

Hydrolases acting on glycosidic bonds: chromatographic and electrophoretic separations

We describe analyses of unusual human alpha-amylase, performed in our laboratory and review available methods for amylase study. Electrophoretic and chromatographic methods provide an effective means for the analysis of amylase isoenzymes and unusual amylase. The recent identification of a selective inhibitor and a monoclonal antibody to amylase isoenzyme contributes to rapid routine clinical assays of amylase isoenzymes. However unusual amylases such as variants, macroamylasemia and sialyl salivary-type amylasemia cannot be detected by those conventional methods. The unusual amylases can only be detected by electrophoresis and can be easily characterized by combination study with chromatographic methods. Electrophoretic and chromatographic methods are universal means to validate unusual amylases found in patient sera. Further basal studies are needed to define the roles of salivary amylase in exocrine fluids using those separation techniques.

Preparation and application of Procion Yellow starch for amylase assay

A new starch derivative for the determination of amylase activity has been synthesized by coupling Procion Yellow dye with starch. The product of this reaction is intensely yellow and is easily suspended in water, in neutral buffer solution, and also in acidic solution. Amylase from pancreatin, saliva, urine and serum readily hydrolyzes this chromogenic substrate. A method for determining amylase activity based on the use of Procion Yellow Starch substrate is described. The procedure requires 0.1 ml of sample and an incubation time of 30 min. The soluble chromogen, which is liberated by enzymatic hydrolysis, is measured at 420 nm and the amylase activity-absorbance relationship at this wavelength is linear. The normal range for this method is 50--150 Somogyi units/dl.

A new serum alpha-amylase assay of high sensitivity

The use of chemically modified starch substrates for measurement of serum alpha-amylase activity is described. Action of alpha-amylase on such substrates, in the presence of excess fungal glucoamylase, results in the production of glucose in direct proportion to the amount of alpha-amylase present. The glucose produced is measured by a specific enzymic assay. Results obtained by using this new assay correlate well with activities determined by a conventional saccharogenic assay. The new method is of much higher sensitivity, and is less susceptible to interference, than are most other alpha-amylase assay methods.

False rise of starch-iodine determined amylase values caused by heparin treatment during haemodialysis

A false rise in the levels of serum amylase as determined by a starch-iodine method was observed in patients undergoing haemodialysis and after treatment with heparin. In in vitro experiments, neither dialysis of serum nor addition of heparin produced a corresponding increase. The results showed that lipoproteins, altered by heparin-induced lipoprotein lipase, may have a considerable influence by interacting with starch and thereby partly preventing the formation of starch-iodine complexes. Amyloclastic methods that employ the starch-iodine reaction for determining amylase are therefore not to be used on patients treated with heparin.

A method for quantitating amylase and its use in the investigation of various body fluids

A plate-diffusion technique for the quantitative assay of amylase in body fluids is described which is dependent on the incorporation of a soluble amylopectin-dye complex into agar. The technique correlates well with other established amylase assays, and has a coefficient of variation of 1.45 for amylase levels within the normal range for serum. Normal levels of amylase in serum and urine are reported which agree with those recorded by previous workers, and in addition values of amylase in semen, saliva, and tears are quoted.