A rapid method for the detection of trypsinogen and chymotrypsinogen after electrophoretic separation of pancreas extract on polyacrylamide gel

A kinetic analysis of the inhibition of rat and bovine trypsins by naturally occurring protease inhibitors

The dissociation constants (Ki) of the interaction of 10 naturally occurring inhibitors with rat anionic and bovine trypsins were determined employing three independent methods. Both enzymes bound very tightly (Ki less than 10(-9)) to bovine pancreatic, lima bean, and the Kunitz soybean inhibitors. With the exception of ovomucoid, rat trypsin bound more tightly than bovine trypsin to inhibitors derived from navy bean, lima bean, soybean (Bowman-Birk) and potato and to ovoinhibitor, leupeptin and antipain. These findings emphasize the caution that must be exercised in the interpretation of experiments involving the inhibition of trypsins from heterologous species of animals by naturally occurring inhibitors.

Electrophoretic analysis of pancreatic proteases and zymogen-activating factors in the mouse

Mouse pancreatic proteases were analyzed by one- and two-dimensional electrophoresis. Active proteases that existed in the luminal fluid were separated into at least eight bands in 8% polyacrylamide gel. Pancreatic proteases activated by intestinal extract were separated into at least seven bands. The mobilities of these bands were exactly the same as those of proteases in the luminal fluid except for those of the most cathodal band. Two kinds of trypsin (Try-I group and Try-II) and one kind of chymotrypsin (Chy-I) were determined by specific and nonspecific protease staining. Try-I group and Try-II were derived from different trypsinogens (Try G-I group and Try G-II), whereas Chy-I was derived from a single chymotrypsinogen (Chy G). Although Try G-II was activated by both intestinal extract and by bovine trypsin, Try G-I group activated only by intestinal extract. Intestinal-activating factors were analyzed by two-dimensional electrophoresis. Mouse enterokinase (enteropeptidase EC 3.4.4.8), which can activate bovine trypsinogen, had a slow mobility. In the intestine of the mouse there are several activating factors in addition to enterokinase. Although it is unclear what intestinal-activating factors can activate Chy G, there is a factor that can convert chymotrypsinogen into chymotrypsin directly. These data suggest that intestinal-activating factors play an important role in the activating mechanisms of mouse pancreatic zymogens.

Human pancreatic secretory protein profiles in the search for tumor markers

Pancreatic cancer secretory protein profiles were shown to be different from normals by a microcomputer-assisted analysis of isoelectric focusing patterns. Two acidic protein band regions (pI 3.0 and 4.5) of the pancreatic carcinoma profiles were significantly increased, and eight protein bands (pI 3.7, 5.0, 5.5, 6.5, 6.9, 7.3, 8.0, greater than 10.0) were significantly decreased. Highly significant decreases occurred at pH 7.3 (chymotrypsinogen) and at pH 5.0 (procarboxypeptidase Al, DNase I) in nonactivated specimens. The ratio between the absorbance points at 2.08 and 2.63 cm from the anode in each protein pattern differentiated the pancreas cancer specimens from the control group. Profiles found for the control group gave pI values similar to those found in the literature. The potential value of these findings in the search for tumor markers warrants further investigation as to whether these specimens can be differentiated from those from chronic pancreatitis patients.

Effect of diet composition on the protein synthetic pattern of the rat pancreas after a feeding period of five days

Rats were fed for five days on a protein-rich and on a carbohydrate-rich diet, respectively. One half of the pancreas of these rats was incubated with [3H]leucine and the other half with [14C]leucine and extracts from these pancreas halves were prepared. Mixtures of the differently labeled extracts were subjected to electrophoresis towards the anode as well as towards the cathode on a polyacrylamide gel containing urea at pH 8.5. Several secretory enzymes could be identified on the gels. Along the gels the 3H : 14C ratio was determined in 1 mm slices. The results show that after five days of feeding a diet there is some adaptation to diet composition. Generally rather small changes in synthetic rate occur. Only one component, the cathodic chymotrypsinogen shows an important difference in synthetic rate under the two circumstances.

Rapid zymogen activation and isolation of serine proteases from an individual mouse pancreas by affinity chromatography: genetical heterogeneity of chymotrypsins of Mus musculus

A rapid method to prepare homogeneous fractions of the various chymotrypsins and trypsins from a single mouse pancreas (130-150 mg wet weight) is described. The method was applied to investigate intra-species variation on a molecular level using chymotrypsins as biochemical indicators. The conditions for optimal extraction of the zymogens in the homogenized pancreas have been studied. DNA had to be removed from the homogenate to obtain maximum chymotrypsin yields (approximately 1% of the wet weight of the pancreas). The activation was initiated by immobilized bovine trypsin that was removed by filtration. Then chymotrypsinogens in the homogenate were activated by mouse trypsin. After completed activation homogeneous chymotrypsins (one anionic and one cationic form) could be isolated in an one step analytical affinity chromatographic separation, using soybean trypsin inhibitor bound in Sepharose as a protease specific adsorbent. The end products were characterized by isoelectric focussing, amino acid composition, enzymatic parameters, molar extinction coefficient, and the number of polypeptide chains. Hereby, the existence of two chymotrypsinogen loci in the mouse genome could be demonstrated. Differences in structure and function between the corresponding enzymes from the two strains were found. This allelomorphism was verified in the crossing of the off-spring.