Physiological studies of exocrine pancreatic secretion in conscious rats. 3. Communication. Separation and determination of enzymes by gel-electrophoresis

1. A method is described for the electrophoretic separation and following quantitative determination of the different protein fractions of pancreatic juice. 2. A polyacrylamide (PAA) gel-electrophoresis is performed in two systems: one anionic at pH = 9.0 with 7.5% PAA and a cationic one at pH = 5.0 with 10% PAA. 3. After about two hours of separation using a current of 3 and 4 mA respectively, the gels are stained with Amido-black 10B after fixation of the proteins with acetic acid. 4. The colour in excess is removed with acetic acid. 5. The coloured bands are isolated by cutting. 6. Evaluation of the colour by NaOH and determination of the colour intensity by photometry. 7. Evaluation of the colour extinction as relative percentages of the different protein and enzyme fractions. (Extinction of total dye = 100%) 8. There are at least 13 bands in the cationic system and about 7 additional ones in the anionic system distinctly separated, 12 of them could be identified using enzymatic methods. 9. Evidence is given that the colour intensity has a linear relationship to enzyme activity. 10. The validity of the presented method is discussed and compared with other electrophoretic methods.

Diagnosis of chronic pancreatitis by measurement of lactoferrin in duodenal juice

Lactoferrin is a non-enzymatic secretory protein of human pancreas and is specifically increased in pancreatic juice of patients with chronic pancreatitis. Duodenal contents being easier to obtain than pure pancreatic juice, the possibility of using lactoferrin measurement in duodenal juice as a diagnosis test for chronic pancreatitis was explored. Forty-eight patients were studied. Duodenal juice was obtained devoid of salivary contamination by a special double lumen tube. Under these conditions lactoferrin secretion (concentration and output) is increased in patients with chronic pancreatitis. When expressed as the ratio of lactoferrin to lipase units, there was no overlap between chronic pancreatitis and other pancreatic disease or controls. The simplicity and the reproducibility of the technique on a material as readily available as duodenal juice confirms the diagnostic value of lactoferrin measurement in the assessment of patients with suspected pancreatic disease.

Regulation of lipase activities in rat brain in vitro

Regulation of acid and neutral lipase activities in rat brain was examined in vitro. Both activities were decreased by SDS, CuCl2 and ZnCl2 and by delipidation. The neutral lipase activity was also markedly reduced by N-ethylmaleimide and PbCl2. The activity of delipidated preparation was increased by addition of phosphatidyl choline at both pH 5.5 and 7.5 and by phosphatidyl serine at acidic pH value. Pretreatments of the enzyme preparation with phospholipase A and trypsin reduced the lipase activities at both pH values. It is suggested that phospholipids play an important role on lipase activity in brain.

Studies on lipase in rat brain

Lipase activity was measured in homogenates of rat cerebral hemispheres using radioactive glycerol trioleate emulsified with Triton X-100 as substrate. The labeled oleic acid was separated from the ester with a methanol-chloroform-heptane mixture. Under these assay conditions, the activity showed pH optima at about 5.5 and 7.5. The final products of these lipase activities were suggested to be free fatty acid and glycerol.

High milk lipase activity associated with breast milk jaundice

Human milk samples that inhibit bilirubin-UDP-glucuronyl transferase (UDPGT) activity in vitro have been associated with prolonged unconjugated hyperbilirubinemia in newborn infants. We measured the concentration of nonesterified fatty acids (total and individual fatty acids), total fat and protein, and lipase activities (with and without bile salt stimulation) in milk samples from two groups of women. Women whose infants had prolonged unconjugated hyperbilirubinemia and whose milk inhibited the activity of UDPGT were in the first group (N = 9). Volunteers with healthy infants acted as controls. Inhibitory milk contained significantly more nonesterified fatty acids (total, palmitic, and oleic) than did controls. Fat and protein concentrations and bile salt-stimulated lipase activities were similar in the two groups. Unstimulated lipase activity was higher in the inhibitory milks (11.9 +/- 0.8 mM x min-1 x ml-1) than in the controls (6.0 +/- 0.1 mM x min-1 x ml-1) (P less than 0.01). The specific activity (mM x min-1 x mg protein) of unstimulated lipase was also significantly higher in the inhibitory milks (P less than 0.0001). The high nonesterified fatty acid levels in inhibitory milks is accounted for by the elevated unstimulated lipase activities. How these circumstances lead to jaundice in the infants remains to be shown.

[Lipase and phospholipase C from Staphylococcus aureus of different origin. I. Determination and occurrence (author's transl)]

Lipase and phospholipase C from Staphylococcus aureus of different origin were demonstrated qualitatively by agar diffusion on tributyrin- and lecithin agar. On test media with either 0,3% Na-azide or 0,3% KCN lipase-activity was not inhibited, phospholipase C, on the other hand, completely blocked (Table 1, Fig. 2). In this manner a tentative differentiation was possible between lipase and phospholipase C. For the quantitative determination of lipase the hydrolysis of p-nitrophenyl palmitate proved to be most useful (Fig. 1). S. aureus-cultures of human origin produced more often and more actively lipase and phospholipase C than those from cattle (Table 2).

[Isolation and characteristics of Penicillium roqueforti lipases]

Lipase were isolated from Penicillium roqueforti 141, purified and their properties were studied. Proteins were precipitated with (NH4)2SO4 from the cultural broth of this organism, and then subjected to gel filtration through Sephadex G-100 and chromatography on DEAE-cellulose; the procedure yielded a purified preparation consisting of three lipolytically active proteins. Disc electrophoresis in polyacrylamide gel confirmed the homogeneity of the lipases. The molecular weights of the enzymes were 7930, 9100 and 11 420 respectively, according to the data of gel filtration through Sephadex G-150. The lipases differed in their substrate specificity. Lipase III was most active in hydrolysis of plant oils containing mainly unsaturated fatty acids. Lipase II most effectively hydrolyzed synthetic triglycerides containing saturated fatty acids, in particular, tricaproin, tricaprilin and trimyristin. Tributyrin was more actively hydrolyzed with lipase I as compared to lipases II and III.

Characterization of triacylglycerol lipase activity in human amniotic fluid

A radiochemical assay was used to measure the triacylglycerol lipase activity found in normal human amniotic fluid at term. Enzyme activity was characterized in a partially purified extract of amniotic fluid and was found to be optimal at pH 8.0 +/- 0.2 in the presence of 5mM sodium taurocholate, with the use of emulsified tri-[3H]oleoyl glycerol as the substrate. The assay described made it possible to determine the lipase activity in as little as 25 microliters of a 12,000 x g supernatent of whole amniotic fluid as the source of enzyme. The lipase appeared to be distinct from another triacylglycerol lipase measurable in fetal membranes. In turn, it was shown that the amniotic fluid enzyme exhibited several catalytic properties which resembled those of pancreatic lipase. i.e., its substrate specificity, the bimodal effect of bile salt, and the influence of authentic pancreatic colipase on the catalytic process. The results suggest that the assay of triacylglycerol lipase activity may be clinically useful in the detection of enzyme abnormalities in human amniotic fluid.

[Localization of the extracellular lipase in Candida paralipolytica yeasts]

The localization of lipase in the cells of Candida paralipolytica was studied for the first time by the techniques of electron cytochemistry and immunocytochemistry. Lipase is formed at the outer surface of the cytoplasmic membrane and often is confined to its invaginations. The reaction products were detected in individual parts of the periplasmic space, in the cell wall, and in its exofibrillar components. Apparently, lipase is formed on the ribosomal-membrane complex. The above pattern is observed only in the cells with a high lipase activity, but not in the control. The two techniques gave similar results. A series of electronograms are presented.

Partitioning of staphylococcal delta haemolysin

The behaviour of the biologically active components present in crude delta haemolysin was followed during various fractionation procedures utilised in the purification of delta haemolysin. Most chromatographic techniques yielded multiple peaks of delta haemolysin. None of the procedures completely separated delta haemolysin from the other components of crude culture filtrates. Efforts to purify delta haemolysin should be renewed.

Immunochemical assay of rat postheparin plasma triacylglycerol lipases

Immunochemical methods for selective measurement of lipoprotein lipase and hepatic lipase activities in rat postheparin plasma are described and validated. Lipoprotein lipase was measured using a substrate containing 10% serum and 0.1 M NaCl after inactivation of hepatic lipase with a specific antiserum. Hepatic lipase was measured at 1.0 M NaCl with a serum-free substrate. The heparin dose-response curve indicated maximum relase of both activities at a heparin dose of 500 IU/kg. The lipase activities in rat postheparin plasma were 3 to 4-fold higher than those in human postheparin plasma. The LPL activity in female rats was significantly higher than in males whereas there was no sex difference for hapatic lipase.

Lactoferrin and albumin in human pancreatic juice: a valuable test for diagnosis of pancreatic diseases

Lactoferrin and albumin concentrations in pure pancreatic juice were studied by radial immunodiffusion in 81 patients. Lactoferrin concentration (% of total protein) was specifically increased in patients suffering from chronic calcifying pancreatitis (mean +/- SE: 0.169 +/- 0.024) and no overlap was observed with patients suffering from other pancreatic diseases (0.008 +/- 0.001), organic nonpancreatic diseases (0.011 +/- 0.001) and without organic disease (0.01 +/- 0.001). Lactoferrin concentration was not found to be correlated with chronic alcohol consumption or pancreatic insufficiency. Albumin concentration (% of total protein) was increased in patients suffering from chronic calcifying pancreatitis (5.55 +/- 0.49) and other pancreatic diseases (5.45 +/- 1.02). These values were significantly higher (P less than 0.001) than the corresponding values in patients with organic nonpancreatic diseases (1.66 +/- 0.16) and patients without organic diseases (1.46 +/- 0.22). Measuring lactoferrin and albumin in pancreatic juice may aid in the diagnosis of pancreatic disease and in the differentiation of chronic calcifying pancreatitis, even in the earliest stage, from other pancreatic diseases such as pancreatic carcinoma or acute pancreatitis.

Changes in the activities of some digestive enzymes of Channa punctatus, exposed chronically to mercuric chloride

The effect of a chronic exposure to sublethal concentration of mercuric chloride (0.3 mg/l) on the activities of some enzymes in the digestive system of the teleost fish Channa punctatus was examined after 15 and 30 days of treatment. Glucose-6-phosphatase was significantly inhibited in the intestine and pyloric caeca. No marked alterations were observed in the activities of maltase and lactase except for elevation in maltase activity and inhibition in lactase activity in the intestine and pyloric caeca after 15 days of treatment. Three peptidases (aminotripeptidase, glycylglycine dipeptidase and glycyl-1-leucine dipeptidase) showed decreased activities in all parts of the digestive system. A decrease was also observed in the activity of lipase except for the stomach where inhibition after 15 days was insignificant. The results indicate that the activities of all the enzymes examined are inhibited in intestine and pyloric caeca and digestion of proteins and lipids may be more affected by mercury than the digestion of some carbohydrates.

A selective deficiency of hepatic triacylglycerol lipase in guinea pigs

The properties of postheparin plasma triacylglycerol-hydrolyzing enzymes were investigated in guinea pig and rat. In rat, lipoprotein lipase and hepatic triacylglycerol lipase were separated on a heparin-Sepharose affinity chromatography. In postheparin plasma of guinea pig, however, hepatic triacylglycerol lipase was almost completely absent, while lipoprotein lipase was present. Hepatic triacylglycerol lipase was also deficient in the liver tissue extract of guinea pig. Plasma lipoprotein compositions of high-fat fed and control guinea pigs were analyzed. One of the outstanding changes found in high-fat fed animals was the presence of chylomicronemia. One guinea pig showed gross hyperlipemia with triacylglycerol concentrations of 2715 mg/100 ml. Plasma triacylglycerol concentrations of each lipoprotein fraction of very low density, intermediate density, low density and high density lipoproteins from high-fat fed animals were almost the same as those of the corresponding lipoprotein fractions from controls. Discussion was focused on the development of chylomicronemia in relation to the defects of triacylglycerol-hydrolyzing enzyme systems in this animal.