Proteolytic inactivation of human leukocyte elastase

Human leukocyte elastase can be proteolytically inactivated by bovine pancreatic trypsin. Neither porcine pancreatic elastase nor bovine pancreatic chymotrypsin causes inactivation of leukocyte elastase, nor are trypsin, pancreatic elastase, or chymotrypsin themselves susceptible to proteolysis. The trypsin-catalyzed inactivation of leukocyte elastase can be slowed by inhibition of trypsin with benzamidine or by occupation of elastase's active site with elastatinal.     

Formation of trypsin inhibitors during alkaline treatment of proteins

Casein is submitted to a severe alkaline treatment (NaOH 0,2 or 0,5 N, 1 hr., 80 degrees C). The hydrolysis by pancreatic enzymes (trypsin or chymotrypsin) is reduced in vitro and, in the case of the more severe treatment, stopped. After an extended (24 hrs.) trypsin and pronase hydrolysis, it is shown, by affinity chromatography, that peptides, which are not hydrolysable, can bind to trypsin and inactivate this enzyme in vitro.     

Endocrine and exocrine pancreatic function after camostate-induced growth of the organ

It is well known that oral administration of camostate induces hyperplasia and hypertrophy of the rat pancreas. It is not clear, however, whether pancreatic hormone and enzyme secretion are affected by camostate treatment.In rats, daily administration of 200 mg camostate/kg b. wt for 14 days significantly increased pancreatic weight and pancreatic content of DNA, protein, amylase, lipase, trypsin and chymotrypsin, as well as the amount of insulin, glucagon and somatostatin. In the intact animal, blood glucose levels and serum concentrations of insulin and glucagon in response to an oral glucose load were not impaired after camostate treatment. In the isolated perfused pancreas, however, insulin and glucagon secretions were reduced, whereas somatostatin release was not affected. The volume of pancreatic juice produced by the unstimulated isolated perfused organ, as well as protein and enzyme secretion, were increased after camostate treatment. Likewise, the isolated perfused pancreas from camostate-treated rats secreted a larger volume of pancreatic juice and more protein in response to cholecystokinin (CCK), while enzyme secretion was affected in a non-parallel manner: amylase release was markedly reduced, lipase release was unchanged, and release of trypsin and chymotrypsin was increased.     

Exocrine pancreatic enzymes in cycloheximide treated rats

Summary Cycloheximide, even in a dose of 0.25 mg/kg administered s.c. to rats stimulated by pancreozymin and secretin, inhibited lipase activity in pancreatic juice. Lipase activity in serum of control animals was inhibited by cycloheximide. The secretion of trypsin and chymotrypsin was also decreased.     

Specific inhibition of human leukocyte elastase by substituted alpha-pyrones

Several a-pyrones have been synthesized and investigated for their in vitro inhibitory activity using a-chymotrypsin (a-CT), porcine pancreatic elastase (PPE) and human leukocyte elastase (HLE). 4-Hydroxy-6-undecyl-2H-pyran-2-one 4, 4-Hydroxy-6-[(1-butyl)heptyl]-2H-pyran-2-one 5 and 4-Methoxy-6-[(1-butyl) heptyl]-2H-pyran-2-one 6 were found to be specific inhibitors of HLE. These compounds constitute a promising new class of HLE inhibitors.     

Anti-elastase of human pancreas: preparation and biological interest

The present paper deals with the use of a new technique in type II human pancreatic elastase studies based on the use of a reversible immune-adsorbent which provides a unique specificity. According to the type of ligand linked on activated Sepharose, the elastase or its antibody in Rabbit could be obtained, in very pure form, in a one step process. The anti-human pancreatic elastase II, which specifically inhibits the enzyme, may be used in therapy whenever the elastase-inhibitor system becomes unbalanced.     

Enhancing effect of heparin on aprotinin activity

Summary Preincubation of heparin with aprotinin enhanced the inhibitory effect of aprotinin on the esterolytic activity of trypsin, but did not change its effect on the proteolytic activity of trypsin or on the esterolytic and proteolytic activities of chymotrypsin.     

Specific inhibition of human leukocyte elastase by substituted alpha-pyrones

Summary Severala-pyrones have been synthesized and investigated for their in vitro inhibitory activity usinga-chymotrypsin (a-CT), porcine pancreatic elastase, (PPE) and human leukocyte elastase (HLE). 4-Hydroxy-6-undecyl-2H-pyran-2-one4, 4-Hydroxy-6-[(1-butyl)heptyl]-2H-pyran-2-one5 and 4-Methoxy-6-[(1-butyl)heptyl]-2H-pyran-2-one6 were found to be specific inhibitors of HLE. These compounds constitute a promising new class of HLE inhibitors.Acknowledgments. We are grateful to the Petroleum Research Fund of the American Chemical Society (Grant No. 13058-B4), the American Lung Association and the Office of Sponsored Research of Wichita State University for generous financial support of this work. This work was also supported by NHLBIGrant 5PO1HL20994 and the Council for Tobacco Research, USA-Inc. Grant 901B.     

Modification of effects of biologically active peptides,caused by enzyme treatment,on the excitability of identifiable giant neurones of an African giant snail (Achatina fulica Férussac)

Summary Physalaemin, which excites an identifiable molluscan giant neurone (the TAN, tonically autoactive neurone), lost the effect after the trypsin treatment. Unexpectedly, this peptide shows an inhibitory effect on the same neurone after chymotrypsin treatment. Deamino-dicarba-(d-d-)oxytocin and d-d-Arg-vasotocin, which excite another identifiable neurone (the PON, periodically oscillating neurone) continue to show the effect after chymotrypsin treatment (6 h). But d-d-Arg-vasotocin losts the effect on the PON after trypsin treatment.The authors thank Dr Sadaaki Iwanaga of Osaka University and Dr Atsuo Inoue of Daiichi Pharmaceutical Co. for their helpful advice, and Miss Hiroko Tamura for her technical assistance.     

Fragmentation of myosin A-1 light chain of fast muscle by trypsin]

Limited proteolysis of myosin by such proteolytic enzymes as trypsin, chymotrypsin or papain produces typical fragmentation of its heavy chain. Presently evidence is given that trypsin treatment cleaves the alkali light chain A-1 (20,700 dalton) to a shorter (ca 20,000 dalton) chain. The two "essential" thiols (SH-1 and 2) of moysin were alkylated with 17-C-N-ethylmaleimide and a non-negligible amount of radioactivity was also found in the two alkali light chains. Using the specific radioactivity of alkali light chain A-1 it was possible to identify it among heavy chain fragmentation products. The molecular weight of the newly formed A-1 indicates that limited tryptic cleavage of this A-1 confers on it a closer similarity with alkali light chain A-2.     

Resistance of purified cholera toxin to enzymatic treatment with pancreatic elastase and papain

Summary Treatment of Cholera toxin with pancreatic elastase and papain in vitro shoed a high resistance of the toxin molecule to these enzymes, under non-denaturing conditions or in the presence of 2M urea. These experiments support the hypothesis of a particularly stable molecular structure of the toxin, as an explanation of its activity in the intestinal lumen where the pancreatic proteases are active.     

Effect of pancreatic duct ligation on exocrine pancreatic function and structure in the rabbit

4 weeks after pancreatic duct ligation in the rabbit, fecal and luminal chymotrypsin were detected in concentrations similar to the control group. Pancreatic changes in the ligated group were marked dilatation of the main pancreatic duct, proliferation and distention of ductules and fibrosis. Despite pancreatic duct ligation and fibrosis, proteolytic enzymes continued to secrete into the duodenal lumen. These results suggest that pancreatic duct ligation in the rabbit is not associated with total pancreatic insufficiency.     

Magnesium enhances human pancreatic elastase digestion of 125I-labeled elastin

The effect of some divalent cations, especially Mg++, on elastinolysis by porcine or human pancreatic elastase has been determined using 125Iodine-labeled elastin as substrate. Elastin degradation was significantly increased in the presence of 10(-3) M Mg++. If elastin was pre-incubated with 0.5 (w/v) Triton, there was a further increase in elastinolysis to 2.6 times the original rate.     

Spontaneous phospholipase A activity of rat pancreatic homogenates]

Rat pancreas presents a spontaneous phospholipase A activity which appears before trypsin activation at optimal pH 6.5. The responsible enzyme is independent of pancreatic prophospholipase A, as can be seen through experiments done in the presence of trypsin inhibitors. On the other hand, this enzyme is distinct from excretory phospholipase which is more active and whose optimal pH is 8.8. Thermostability and insensibility of spontaneously active phospholipase A to DFP differentiate it from lipase, carboxyl-esterhydrolase and lysophospholipase, respectively.     

Bombesin promotes pancreatic growth in suckling rats

The pancreatic growth promoting effect of long term administration of bombesin was investigated in suckling rats. The authors showed that bombesin given in 10 micrograms/kg b.wt doses s.c. every 8 h for 10 days from the day of parturition stimulated pancreatic growth: it increased pancreatic weight, protein and DNA content, trypsin and amylase activity and trypsin/DNA ratio. Conclusion: Bombesin is an effective stimulator of pancreatic growth in suckling rats.     

Effect of pancreatic duct ligation on exocrine pancreatic function and structure in the rabbit

Summary 4 weeks after pancreatic duct ligation in the rabbit, fecal and luminal chymotrypsin were detected in concentrations similar to the control group. Pancreatic changes in the ligated group were marked dilatation of the main pancreatic duct, proliferation and distention of ductules and fibrosis. Despite pancreatic duct ligation and fibrosis, proteolytic enzymes continued to secrete into the duodenal lumen. These results suggest that pancreatic duct ligation in the rabbit is not associated with total pancreatic insufficiency.This study was supported by the Kansas University Endowment Association (Grant No. 73-2550), General Research Support (Grant No. 2553 and 1522-14) and a grant from Kaw Valley Heart Association.     

New low-molecular inhibitors of pancreatic elastase with possible in vivo application: alkylamides of N-acylated tripeptides

Out of a series of alkylamides of N-acylated tripeptides, Glt-(Ala)2-Pro-NH-Et and Glt-(Ala)3-NH-Pr were found to be potent inhibitors of porcine and human pancreatic elastase, and because they are free of toxic groups they might be considered for in vivo application.     

Bombesin promotes pancreatic growth in suckling rats

Summary The pancreatic growth promoting effect of long term administration of bombesin was investigated in suckling rats. The authors showed that bombesin given in 10 g/kg b.wt doses s.c. every 8 h for 10 days from the day of parturition stimulated pancreatic growth: it increased pancreatic weight, protein and DNA content, trypsin and amylase activity and trypsin/DNA ratio. Conclusion: Bombesin is an effective stimulator of pancreatic growth in suckling rats.     

Magnesium enhances human pancreatic elastase digestion of125I-labeled elastin

Summary The effect of some divalent cations, especially Mg⁺⁺, on elastinolysis by porcine or human pancreatic elastase has been determined using¹²⁵Iodine-labeled elastin as substrate. Elastin degradation was significantly increased in the presence of 10^–3 M Mg⁺⁺. If elastin was pre-incubated with 0.5 (w/v) Triton, there was a further increase in elastinolysis to 2.6 times the original rate.