Affinity electrophoresis of human serum alkaline phosphatase isoenzymes in agarose gel containing lectin

Separation of alkaline phosphatase isoenzymes using affinity electrophoresis in agarose gel containing lectin is described. The bone and biliary isoenzymes precipitate during electrophoresis and are clearly separated from the liver isoenzyme. The liver, intestinal and placental alkaline phosphatases are essentially not affected by the lectin. The migration distances of the precipitating bone and biliary fractions vary with their alkaline phosphatase activity. The bone isoenzyme is more heterogeneous than the biliary isoenzyme with respect to interaction with lectin forming both insoluble and soluble complexes. Affinity electrophoresis in agarose gel containing lectin can be used for quantitation by densitometry of liver and bone isoenzymes in sera containing only these two fractions but must be combined with conventional electrophoresis, preferably in agar gel, if biliary, intestinal, or placental isoenzymes are also present.     

Characterization of serum alkaline phosphatase isoenzymes by affinity electrophoresis in agarose gel containing lectin combined with agar gel electrophoresis

The combined use of affinity electrophoresis in agarose gel containing lectin and of agar gel electrophoresis for the quantitation of liver, bone, biliary and intestinal alkaline phosphatase isoenzymes is described. Sera from patients with various diseases and from normal subjects (blood donors) have been analyzed. Data from normal subjects show that the bone isoenzyme is the predominant fraction (about 62%) in adults. The relative proportions of the alkaline phosphatase isoenzymes are similar in both sexes in adulthood (21-50 years). The higher alkaline phosphatase activity found in men than in women (ages 21-50 years) is due to higher values for both liver and bone isoenzymes. The difference between men and women tends to decrease after the age of 50 mainly due to an increase of the bone isoenzyme in women.     

Two new methods for separating and quantifying bone and liver alkaline phosphatase isoenzymes in plasma

We describe two new methods for the separation and quantification of the bone and liver isoenzymes of alkaline phosphatase (EC 3.1.3.1) in plasma. In the first, we use wheat-germ lectin to precipitate the bone isoenzyme. About 80% of this, but minimal liver isoenzyme, is precipitated. The activity of the bone isoenzyme is calculated from measuring the alkaline phosphatase activity in the precipitate, that of liver alkaline phosphatase by subtracting the activity of the bone isoenzyme from total alkaline phosphatase activity. The liver fraction will also contain biliary, intestinal, and placental alkaline phosphatase if these are present in the original plasma, but correction for such activity is readily made. In the second method, samples are separated on cellulose acetate membranes that, before electrophoresis, have been soaked in buffer containing wheat-germ lectin. The bone isoenzyme is retarded and clearly separated from the liver fraction, allowing these isoenzymes to be quantified by densitometry. Both methods are rapid, reproducible, and suitable for use in the diagnostic laboratory.     

Improved electrophoretic resolution of human serum alkaline phsophatase isoenzymes in agarose gel by Triton X-100.

Triton X-100 caused the liver isoenzymes of alkaline phosphatase in some serum samples to separate into two fractions on agarose gel electrophoresis. One of these fractions migrated at the rate of the original one, and one migrated more slowly. The latter fraction corresponded to a fast-moving component on electrophoresis in Cellogel and seems to be identical with a slowly moving isoenzyme in starch and polyacrylamide gel electrophoresis. The migration rates of the bone, placental, and intestinal isoenzymes were unaltered, but the fractions appeared sharper.     

Reference limits of bone and liver alkaline phosphatase isoenzymes in the serum of healthy subjects according to age and sex as determined by wheat germ lectin affinity electrophoresis

Wheat germ lectin affinity electrophoresis was employed for quantitating the bone and liver isoenzymes of alkaline phosphatase (EC 3.1.3.1) in serum and for determining the reference limits of each isoenzyme activity in 488 healthy individuals. Bone phosphatase activity was detected even after bone growth, accounting for 60-70% of the total activity. An increase in bone phosphatase activity occurred in older females, but there was a decrease in older males. Liver phosphatase activity gradually increased with age in both sexes, males showing higher activity than females at all ages. Wheat germ lectin affinity electrophoresis of serum alkaline phosphatase is a simple and useful method for quantitating bone and liver alkaline phosphatase activities.     

Association of high-molecular-mass and electrophoretically atypical alkaline phosphatases

Polyacrylamide gel electrophoresis of alkaline phosphatase may yield abnormally migrating fractions; these include high-molecular-mass alkaline phosphatase, which remains at the gel origin, and immunoglobulin-alkaline phosphatase complexes, which have a mobility approximately 1/3 that of liver isoenzyme. We performed a retrospective study of 19 patients whose sera exhibited atypical alkaline phosphatase fractions, defined as bands whose mobility was slower than bone, liver, or intestinal alkaline phosphatase; 17 had a mobility approximately 1/3 that of liver isoenzyme and 16 also exhibited gel origin enzyme activity or high-molecular-mass bands. The strong association of the atypical and high-molecular-mass alkaline phosphatases suggests that they may be structurally related, both consisting of either immunoglobulin-enzyme complexes or membrane-alkaline phosphatase complexes. This hypothesis is supported by (1) one serum available for investigation containing alkaline phosphatase-immunoglobulin complexes in both abnormally migrating fractions, but on detergent treatment showing no evidence of membrane-bound enzyme; (2) detergent treatment of serum from patients with only high-molecular-mass alkaline phosphatase creating bands with a mobility of approximately 1/3 that of the liver isoenzyme.     

Alkaline phosphatase isoenzymes resolved by electrophoresis on lectin-containing agarose gel

With this electrophoretic method the liver, biliary, and bone isoenzymes of alkaline phosphatase are clearly separated on agarose gels. Wheat-germ lectin, incorporated in the gel matrix, binds the bone isoenzyme selectively, forming a precipitate near the origin. Neither liver nor biliary isoenzyme is affected. Activity staining with an indigogenic dye substrate reveals the liver isoenzyme migrating nearest the anode, followed by the biliary and bone isoenzymes. Results are generally similar to those of electrophoresis on cellulose acetate. However, the lectin-agarose gels better resolve the liver and bone isoenzymes, and heat treatment of samples is not required before electrophoresis.     

Incubation with neuraminidase and affinity electrophoresis with wheat-germ lectin compared for separating and quantifying alkaline phosphatase isoenzymes in plasma

Of 98 patients' specimens examined for alkaline phosphatase (EC 3.1.3.1) isoenzymes by electrophoresis on cellulose acetate membrane after incubation with neuraminidase, 50 showed only a single liver or bone isoenzyme staining band; in 15 of these, the tissue origin of the fraction could not be accurately identified from its electrophoretic location. In the remaining 48 specimens, both liver and bone fractions were identifiable, but in only 25 of these was the electrophoretic resolution sufficient to yield separate peaks on densitometry. In contrast, both liver and bone alkaline phosphatase isoenzymes were identified in 95 of the 98 specimens by affinity electrophoresis involving wheat-germ lectin, the detection of both fractions being in agreement with the results of sequential heat inactivation. The tissue origin of the enzyme bands was readily ascertainable from their consistent electrophoretic location in this medium, and in 89 of the specimens the isoenzyme fractions could be resolved into separate peaks on densitometry. We conclude that resolution of liver and bone alkaline phosphatase by incubation with neuraminidase followed by cellulose acetate electrophoresis is greatly inferior to that obtained by wheat-germ lectin affinity electrophoresis.     

Atypical alkaline phosphatase isoenzyme in serum from a patient with Hodgkin's disease

An alkaline phosphatase isoenzyme that did not move from the origin in agarose gel electrophoresis was detected in serum from a 51-year-old woman with Hodgkin's disease. Inhibitor and heat-inactivation studies of the patient's serum alkaline phosphatase showed properties resembling those of both liver and bone isoenzymes. No immunoglobulin or high-molecular-mass complexes with the alkaline phosphatase isoenzyme were detected. The relative molecular mass (Mr) of the atypical alkaline phosphatase isoenzyme was 182 000, that of the liver alkaline phosphatase isoenzyme control 170 000. Treatment of both of these isoenzymes with neuraminidase gave a product with an Mr of 140 000. We propose that a post-translational modification increased the carbohydrate content of the liver alkaline phosphatase isoenzyme, thus changing the charge characteristics of the enzyme and decreasing its electrophoretic mobility. We believe this to be the first report of a post-translational modification in a heat-sensitive isoenzyme of alkaline phosphatase.     

The properties and clinical significance of some electrophoretically slow forms of alkaline phosphatase.

Sera from 8 patients with a marked slow-moving alkaline phosphatase band on electrophoresis were investigated. Inhibitor studies and treatment with neuraminidase showed that all the patients had slow bands with alkaline phosphatase properties resembling those of the liver or bone isoenzyme. In no case did the slow band resemble the intestinal isoenzyme. Immunoelectrophoretic and molecular weight studies indicated that the slow band consisted of an IgG-alkaline phosphatase complex of molecular weight 540 000. Serum from a patient with the slow band was able to bind liver or bone, but not intestinal, alkaline phosphatase from other patients to form the slow band. Serum from patients with the slow band probably contains an abnormal IgG molecule which can bind alkaline phosphatase in the ratio 2:1. No clinical condition was common to all 8 patients although most of them had either intestinal or lung disease.     

Microheterogeneity of Kasahara isozyme

The microheterogeneity of Kasahara isozyme was investigated by affinity electrophoresis with Con A as the affinity ligand in combination with polyacrylamide gradient gel electrophoresis. On two-dimensional Con A-containing agarose gel electrophoresis, the Kasahara isozyme was separated into three molecular species. Kasahara isozyme electrophoresed as two distinct bands with enzyme activity on polyacrylamide gradient gel, but liver, intestinal or placental alkaline phosphatase showed only one distinct spot or band on both electrophoreses. One of the three molecular species of Kasahara isozyme separated by Con A-containing agarose gel electrophoresis was extracted from the gel and applied to the polyacrylamide gradient gel electrophoresis again, resulting in the same electrophoretic pattern as that of the original Kasahara isozyme. These findings indicated that the Kasahara isozyme consists of at least four molecular species. The same analysis was conducted with alkaline phosphatase of the HuH-6 cl-5 cell line, which has been reported to release an alkaline phosphatase closely resembling the Kasahara isozyme, and the results were compared with those obtained with the Kasahara isozyme.     

Two macromolecular complexes between alkaline phosphatase and immunoglobulin A in a patient's serum

We report the presence of two separate macromolecular complexes between an immunoglobulin and alkaline phosphatase (EC 3.1.3.1) in the serum of a patient with cholestatic liver disease. The complexes were seen as slow-moving bands on electrophoresis on polyacrylamide gel (70 g/L). Estimates of relative molecular mass for the two bands were 785 000 and 490 000 by gel chromatography on Sephacryl S300, and 640 000 and 420 000 by gradient gel-electrophoresis. Inhibitor and heat-inactivation studies showed that the two bands had similar properties, resembling the liver isoenzyme but more heat stable. Immunological studies suggested that both bands consisted of a complex of liver alkaline phosphatase with kappa type immunoglobulin A.     

Quantitative recovery of alkaline phosphatase and gamma-glutamyl transferase isoenzymes after polyacrylamide gel electrophoresis

Loss of activity of the isoenzymes of gamma-glutamyl transferase and alkaline phosphatase has been shown to occur during electrophoresis on polyacrylamide gel. After studying the possible factors concerned in this loss, reasonable recovery from the gel can be obtained only for the isoenzyme staying at the origin. Maximum recovery is 60% for origin gamma-glutamyl transferase and 92% for origin alkaline phosphatase.     

A novel alkaline phosphatase, a minor component of normal liver phosphatases.

A novel alkaline phosphatase differing from the so-called liver-specific isoenzyme was found in four out of twenty-four normal adult livers. Although the mobility of this enzyme was the same as that of so-called liver-specific alkaline phosphatase on the polyacrylamide gel electrophoretogram, its mobility was not altered following neuraminidase treatment, while that of the liver-specific enzyme was affected by the same treatment. Both enzymes also differed in other enzymatic and immunologic properties. The enzyme, however, resembled the so-called intestinal alkaline phosphatase in many enzymatic and immunologic properties. Thus, the inhibition patterns by amino acids, EDTA and inorganic phosphate, the pH optima, KM values for phenyl phosphate and reactivity with anti-intestinal alkaline phosphatase antibody were quite similar for both enzymes. Differences in the properties of this enzyme and intestinal alkaline phosphatase were in sensitivity to denaturation by treatment with heat and urea and to inhibition by Levamisole. The possible origin of the enzyme in normal liver and its relationship to the Kasahara isoenzyme and fetal intestine-type in hepatoma is discussed.     

Studies of the biochemical and immunological properties of human neutrophil alkaline phosphatase with comparison to the established alkaline phosphatase isoenzymes

A range of affinity column chromatographic procedures and various inhibitors have been used to compare human neutrophil alkaline phosphatase with the three established isoenzymes. The column chromatography studies have clearly distinguished neutrophil alkaline phosphatase from the intestinal isoenzyme. Inhibition studies withl-phenylalanine,l-homoarginine and levamisole have revealed a distinct pattern of inhibition for liver, kidney and neutrophil alkaline phosphatase which is quite different from the pattern shown by placental and intestinal alkaline phosphatase. Immunospecificity experiments with a monoclonal antibody raised to human liver alkaline phosphatase have shown that it cross reacts with alkaline phosphatase from kidney, bone and neutrophil. In all studies, neutrophil alkaline phosphatase has virtually identical properties to that of liver, kidney and bone alkaline phosphatase. This is strong evidence that neutrophil alkaline phosphatase is a product of the same structural gene which codes for the liver/bone/kidney group of human alkaline phosphatases.     

Micro-scale two-dimensional electrophoresis of alkaline phosphatase from serum

Isoenzymes of alkaline phosphatase (EC 3.1.3.1) were separated by micro-scale two-dimensional electrophoresis, with isoelectric focusing in capillary gels in the first dimension and polyacrylamide gradient-gel electrophoresis in the second. The isoenzymes detected were identified by several treatments--e.g., incubation with sialidase, papain, Triton X-100, and wheat-germ agglutinin--and by comparison with alkaline phosphatase from liver microsomes. Liver and bone isoforms in normal sera showed overlapping isoelectric points but differed in molecular mass, estimated as 172 and 185 kDa, respectively. Sera of patients with liver disease showed several additional groups of alkaline phosphatase isoforms, two of which were found to consist of multi-molecular complexes. Others probably correspond to incompletely glycated enzyme proteins. A further isoform with a mass of about 250 kDa does not seem to correspond to any known isoform of alkaline phosphatase in serum. With this technique, we demonstrated intra- and interindividual variations of the placental alkaline phosphatase isoenzyme in pregnancy sera.     

碱性磷酸酶同工酶分析在肝、骨性疾病中的鉴别应用

目的对电泳后的碱性磷酸酶(ALP)同工酶进行定量分析测定,用于鉴别诊断肝、骨疾病.方法总ALP活性用日立747测定,将收集的ALP总活性升高的血清用神经氨酸酶处理后,在HELENA电泳仪上做琼脂糖电泳.结果电泳后可将ALP同工酶分成几个独立的区带,其中以肝型及骨型ALP为主,可用于鉴别肝脏疾病、骨疾病及癌症骨转移疾病.结论神经氨酸酶处理的血清经电泳后,能够更加准确的为ALP总活性升高的患者确诊.     

Quantitative fractionation of alkaline phosphatase isoenzymes according to their thermostability.

Continuous monitoring of heat denaturation of a mixture of alkaline phosphatase isoenzymes at 60 degrees C and pH 7.5 permits the simultaneous direct identification and quantitation of three isoenzymes: the placental isoenzyme, the L-phenylalanine-sensitive intestinal isoenzyme, and the liver isoenzyme (hepatocytic). The isoenzyme that is principally of bone origin cannot be identified as such without the help of other diagnostic aids and the patient's medical history. All human tissues contain alkaline phosphatase, many organs more than one of the isoenzymes. Liver alkaline phosphatase, which constitutes 40-50% of normal serum alkaline phosphatase activity, was measured in the serum of persons with various liver diseases. Its activity exceeded normal in all types of liver disease; in 80% of cases this increase was accompanied by increased gamma-glutamyl-transferase activity, but the quantitative correlationship (r = 0.54) was not as good as expected if both enzymes come from the same source and are indices of liver dieases. Liver alkaline phosphatase activity increases in the blood early in liver disease, before most liver tests show abnormalities. The other major isoenzyme of normal serum probably represents a mixture of isoenzymes from bone and reticulo-endothelial and vascular tissues, which all contain the same "very heat-labile" alkaline phosphatase. Cord blood and children's sera contain mostly this very heat-labile isoenzyme.     

Serum alkaline phosphatase isoenzyme patterns in disease

Serum alkaline phosphatase isoenzyme patterns have been obtained using starch gel electrophoresis. The intestinal isoenzyme was detected in about one-third of over 300 serum samples examined. The incidence was high in cirrhosis and chronic renal failure but low in gastrointestinal disease. In serum from some patients the intestinal isoenzyme was the only isoenzyme present. Isoenzymes of unusual electrophoretic mobility were found in the serum of eight patients.     

Isoelectric focusing of neuraminidase-treated alkaline phosphatase isoenzymes on agarose gel

We attempted to separate bone and liver alkaline phosphatase (EC 3.1.3.1) isoenzymes in human serum by isoelectric focusing on agarose gel. We found that in a pH 3-10 gradient the liver and bone isoenzymes focused into so many bands over a narrow pH range such that the information could not be quantified. However, when the bone isoenzyme in serum was first desialylated at 37 degrees C for a minimum of 6 h, catalyzed by neuraminidase (EC 3.2.1.18) at pH 5.8-6.0, we could detect four distinct bands with pls of 6.7, 6.8, 6.9, and 7.0. Under the same conditions, the liver isoenzyme in human serum focused into one band at pH 7.0. The multiple banding we observed for the desialylated bone isoenzyme has not been previously reported. The method is suited as a qualitative technique for detecting the bone alkaline phosphatase isoenzyme in serum.