Differentiation of parotid and pancreatic amylase in human serum

Accurate quantitation of salivary and pancreatic amylase activities in human plasma by microchip electrophoretic separation of the substrates and hydrolysates coupled with immunoinhibition

A high-performance determination system for alpha-amylase isoenzyme activities in human plasma involving microchip electrophoresis with a plastic chip was developed. The combination of microchip electrophoresis for substrate and hydrolysate separation and an immunoinhibition method for the differentiation of isoenzyme activities using antihuman salivary amylase (S-AMY) mAb allowed the highly selective determination of amylase isoenzyme (S-AMY and pancreatic amylase (P-AMY)) activities even in a complex matrix such as a crude plasma sample. We used 8-aminopyrene-1,3,6-trisulfonic acid (APTS)-labeled maltohexaose (G6) as a substrate. Amylase in a human plasma sample hydrolyzed APTS-G6 into APTS-maltotriose (G3) and G3, which was measured as the fluorescence intensity of APTS-G3 on microchip electrophoresis. A double logarithm plot revealed a linear relationship between amylase activity and fluorescence intensity in the range of 5-500 U/L of amylase activity (r2=0.9995, p<0.01), and the LOD was 4.38 U/L. Amylase activities in 13 subjects determined by the present method were compared with the results obtained by conventional methods with nitrophenylated oligosaccharides as substrates, respectively. Good correlations were observed for each method on simple linear regression analysis (both p<0.01). The reproducibilities of within-days for total amylase and P-AMY were 2.98-6.27 and 3.83-6.39%, respectively, and these between-days were 2.88-5.66 and 3.64-5.63%, respectively. This system enables us to determine amylase isoenzyme activities in human plasma with high sensitivity and accuracy, and thus will be applicable to clinical diagnosis.

Hyperamylasemia and S-type isozyme dominance in liver cirrhosis

To investigate the mechanisms of serum amylase abnormalities in liver disease, we determined serum amylase levels, S-type isozyme proportion, clinical symptoms, and laboratory data in 38 cases of histologically confirmed liver cirrhosis and 19 controls. Of the 12 patients who were hyperamylasemic (12/38, 32%), 5 showed S-type isozyme dominance (5/12, 42%), whereas in the 26 normoamylasemic cirrhosis patients, only 5 were S-type isozyme dominant (5/26, 19%). Isozyme percentages were significantly higher (P less than 0.01) in the dominant-S-type cases than in the controls, and S-type dominance was found more frequently in the hyperamylasemic than in the normoamylasemic cirrhosis cases. Only ascites and esophageal varices were observed more frequently as clinical symptoms in the dominant-S-type cases. Our results suggest that amylase is not produced in the human liver, but that the decreased clearance rate of amylase, especially the S-type isozyme, may be a cause of hyperamylasemia and S-type isozyme dominance in cirrhosis.

Serum amylase isoenzyme alterations in acute abdominal conditions

To determine the accuracy of the serum amylase in identifying a pancreatic source, amylase isoenzymes were determined prospectively in 65 patients initially evaluated with a complaint of abdominal pain and associated hyperamylasemia. Isoenzyme patterns were demonstrated by an electrophoretic technique, and the results were correlated with clinical diagnoses. Patients were divided into two diagnostic groups. Group I consisted of 42 patients with clinical findings suggesting pancreatitis. P-type isoenzymes were normal or elevated in 31 of these patients (74%), and s-type isoenzymes were normal or elevated in 11 (26%). Group 2 consisted of 23 patients with abdominal pain attributed to causes other than pancreatitis. Four patients (17%) had elevation of p-type isoenzymes, and 19 patients (83%) had predominantly s-type patterns. We conclude that amylase isoenzymes cannot determine unequivocally the cause of hyperamylasemia, but they can enhance the diagnostic specificity of the serum amylase. Elevated serum amylase with a predominant p-type pattern suggests pancreatic disease; elevation of s-type isoenzymes suggests but is not conclusive for, diagnoses other than pancreatitis. Hyperamylasemia with a normal isoenzyme pattern occurred in a few patients in both groups, and it was nondiagnostic.

Biochemistry of human alpha amylase isoenzymes

The purpose of this article is to review recent literature on the isoenzymes of alpha amylase. Although some studies are cited from the literature of fields other than clinical biochemistry, the aim is to bring together findings that may be of interest to clinical laboratory physicians and scientists. It is hoped that this will be useful in suggesting further studies of amylase. To this end, the review is more selective than exhaustive. The review will discuss the history and chemistry alpha amylases, the measurement of amylase and amylase isoenzymes, posttranslational modifications of human amylases, and the genetics of human pancreatic and salivary amylases. Finally, we will discuss other tissue sources of amylase with emphasis on "genital" amylases and their relationship to the amylase found in serous ovarian tumors.

Differential assay of human pancreatic and salivary alpha-amylases in serum using a new fluorogenic substrate

The difference in the mode action of human pancreatic and salivary alpha-amylases on O-6-deoxy-6-[(2-pyridyl)amino]-alpha-D-glucopyranosyl-(1----4)-O-alpha-D - glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D- glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-D-glucitol FG6R), a fluorogenic derivative of maltohexaitol, was found. The products of the enzymatic hydrolysis were analyzed by high-performance liquid chromatography (HPLC) in 8 min. FG6R was hydrolyzed by these enzymes to O-6-deoxy-6-[(2-pyridyl)amino]-alpha-D-glucopyranosyl- (1----4)-O-alpha-D-glucopyranosyl-(1----4)-D-glucose (FG3) and maltotriitol, or O-6-deoxy-6-[(2-pyridyl)amino]-alpha-D- glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D- glucopyranosyl-(1----4)-D-glucose (FG4) and maltitol. Pancreatic alpha-amylase produced more FG4 than salivary alpha-amylase. Taking advantage of the differences in action of the two amylases, a differential alpha-amylase assay in serum was performed. The method is simple and rapid and can be used for routine clinical assays of alpha-amylases.

Isolation and characterization of isoenzymes of human salivary and pancreatic alpha-amylase

Human salivary and pancreatic alpha-amylase (1,4-glucan 4-glucanohydrolase, EC 3.2.1.1) were separated by electrofocusing. In the first case we obtained six isoenzymes with isoelectric points of pH 5.70, 5.72, 6.23, 6.32, 6.73 and 6.88. Human pancreatic alpha-amylase has been separated into eight isoenzymes with isoelectric points of pH 5.72, 5.77, 5.88, 6.05, 6.23, 6.69, 6.72 and 6.95. Some of the isoenzymes were shown to be sialoproteins; others representing about 80% of the total activity did not contain neuraminic acid. The molecular weight of the non-sialoproteinic isoenzymes was found to be about 47 000 in all cases.