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PubMed1978

Immunochemical characterization and cellular localization of pepsinogens in cat and dog.

The antigenic relationships and cellular localization of cat and dog pepsinogens were investigated by electrophoretic analysis, immunodiffusion, immunoelectrophoresis, immunoabsorption, and by immunofluorescence, respectively. Rabbit antiserum to human and hog group I (Pg I) and group II pepsinogens (Pg II) had been previously prepared. Electrophoretic analysis revealed at least eight distinct proteases in extracts of gastric and proximal duodenal mucosa, resistant to alkalinization but destroyed by sequential accidification and neutralization. Rabbit antiserum to Pg I (anti-Pg I) and Pg II (anti-Pg II) produced a single precipitin arc against each extract forming a line of nonidentity. Immunoelectrophoresis of extracts produced a single precipitin arc against anti-Pg I or anti-Pg II. The specificity of the antibodies for the group I or group II pepsinogens was confirmed by immunoabsorption. By immunofluorescnece, both Pg I and Pg II were present in mucous neck and chief cells in fundic mucosa, in the pyloric gland cells in antral mucosa, and Brunner's glands in the proximal duodenum. The results indicate that canine and feline pepsinogens are electrophoretically heterogenous, that canine and feline Pg I share antigenic determinants with each other but not with Pg II, that a similar positive relationship exists for Pg II, and that both Pg I and Pg II are localized to the peptic cell mass, consisting of four types of cells.

Animals↗

PubMed1975

Probable genetic linkage between a locus for human urinary pepsinogen and the HL-A loci.

The genetic basis of familial variation in the relative intensities of human urinary pepsinogen isozymes is not completely clear from family studies. An investigation of the linkage relationships of pepsinogen isozyme 5, considering only segregation for the presence or absence of Pg 5, yields a peak lod score of 4.1 at theta = .1 for linkage with HL-A1 or HL-A2. Added to data from segregation interpreted according to a scheme proposed for the inheritance of intensity differences in Pg 5, the peak lod score becomes 3.0 at theta = .2. Data derived from the segregation of pepsinogen isozyme 4, possibly determined by an allele to that controlling the presence or absence of Pg 5, further reduces the total lod score at theta = .2 to 2.9. The results indicate probable linkage between a locus for urinary pepsinogen and the HL-A loci, but are insufficient to permit any conclusion concerning possible heterogeneity in the linkage relationships of Pg 4 and Pg 5 to HL-A.

Black People↗

PubMed1975

Plasma concentrations of pepsinogen and corticosteroid in relation to gastric lesions in swine.

Plasma pepsinogen and plasma corticosteroid concentrations were found to be unrelated to the presence or severity of gastric lesions in swine. Mean plasma pepsinogen and corticosteroid concentrations were significantly different between collection periods, with significantly higher values occurring during cold weather. Seemingly, plasma pepsinogen and corticosteroid values are neither indicative of susceptibility to, nor of the presence of, gastric erosions or ulcers in swine. However, plasma pepsinogen concentration may be a potential indicator of stress.

Adrenal Cortex Hormones↗

PubMed1979

Purification and characterization of rat pepsinogens whose contents increase with developmental progress.

Two pepsinogens, the contents of which increase with developmental progress, were purified from the gastric mucosa of the adult rat by ammonium sulfate fractionation and chromatography on DEAE-cellulose and DEAE-Sepharose CL-6B columns. The purified zymogens, designated as pepsinogens I and II, were each shown to be homogeneous by polyacrylamide gel disc electrophoresis. Pepsinogen II had a greater electrophoretic mobility toward the anode at pH 8.0 than pepsinogen I. The molecular weights of both zymogens were estimated to be 38,000 by SDS-polyacrylamide gel electrophoresis. The activated enzymes, pepsins I and II, each had the same molecular weight of 32,000. The pH optima for both enzymes were found to be 2.0. The enzymes showed high stabilities at pH 8.0, while they lost their activities within 60 min at pH 10.0. The enzymes were inhibited by pepstatin and diazoacetyl-DL-norleucine methyl ester (DAN). The activities of the enzymes in hydrolyzing N-acetyl-L-phenylalanyl-3,5-diiodo-L-tyrosine (APDT) were about 1/8 of that of porcine pepsin. These results suggest that pepsins I and II are very similar.

Animals↗

PubMed1977

Crystallization and preliminary crystal data of porcine pepsinogen.

Single crystals of porcine pepsinogen, suitable for x-ray diffraction studies, have been grown with lithium sulfate as the precipitant. These pepsinogen crystals were dissolved, activated, and assayed for proteolytic activity. The specific enzymic activity of the dissolved crystalline protein was nearly twice that of the commerical pepsinogen from which the crystals were grown. Incubation at pH 8 before assay demonstrated that the crystals are free of pepsin. This crystal form of pepsinogen belongs to the monoclinic space group C2 with 4 molecules in the unit cell. The unit cell dimensions are a = 104.8 +/- 0.5 A, b = 43.1 +/- 0.1 A, c = 88.4 +/- 0.3 A, and beta = 91.3 degrees.

Animals↗

PubMed1976

Immunochemical study and cellular localization of human pepsinogens during ontogenesis and in gastric cancers.

Gastric pepsinogens were studied by immunoenzymologic and immunohistochemical methods in non-cancerous adult gastric mucosa, in fetal stomach, and in gastric carcinomas. In noncancerous adult mucosa, immunoenzymologic methods showed that pepsinogen II (previously called Pg I-II) was found mostly in fundic or mediogastric extracts, whereas Pg IV was predominant in antropyloric extracts. Pg II was localized by immunofluorescence techniques in the chief cells of deep glands found near the muscularis. Pg II was localized by immunofluorescence techniques in the chief cells of deep glands found near the muscularis. Pg III was present in the superficial zone of deep glands and Pg IV in the surface epithelium and in the superficial glands of the mucosa. In fetal stomach, only Pg IV (which we called the "fetal pepsinogen") was identified by standard immunoelectrophoresis. It was localized by immunofluorescence in the superficial epithelium. However, bidimensional immunoelectrophoresis and immunofluorescence did reveal low levels of Pg II and Pg III by the 8th or 9th week of ontogenesis. Pg II and Pg III were localized in the rudimentary glands near the superficial epithelium. Important differences were noted when gastric carcinomas were compared with normal mucosa. Pg II or Pg III were often absent in the tumor extracts, but Pg IV was regularly and, at times, exclusively identified regardless of the location of the tumor. By immunofluorescence Pg IV was often the only pepsinogen that was characterized in dedifferentiated cancerous cells; this was also true of the calciform cells of some metaplastic gastric mucosa. Pg III was observed rarely, and Pg II never, in cancerous cells. The biochemical modifications of the cancerous tissue closely resemble those of fetal tissue.

Epithelium↗

PubMed1979

Characterization of human pepsin II obtained from purified gastric pepsinogen II.

Human pepsinogen II (PgII) was purified from human gastric mucosa by immunoadsorbents using anti-PgII antiserum. Contaminating pepsinogen I (PgI) was adsorbed by a subsequent anti-PgI immunoadsorbent. PgII was further purified on DEAE-Sphadex A50. By agar gel enzyme electrophoresis (AEE) at pH 8.2 PgII was separated into five proteolytic bands, demonstrated upon acidification and incubation with hemoglobin. PgII was converted to pepsin II (PII) by acidification at pH 2.0 and was immediately separated from its inhibitory peptide and from other substances by DEAE chromatography. Purified PII showed two bands in AEE at pH 5.6 and was immunochemically identical with PgII. The "gastricsin" and "pepsin" purified from acid gastric juice by classical procedures proved to be identical with PII and pepsin I (PI), respectively. PII showed a broad pH range with one maximum at pH 2.9. PII in contrast to PI did not hydrolize N-acetylphenylalanyl-3,5-diiodotyrosine and proved to be more alkali-stable than PI. A modified nomenclature is proposed for the human pepsinogen system.

Electrophoresis, Agar Gel↗

PubMed1979

Effect of intragastric acid on pepsinogen secretion in the rat.

When the osmolarity of intragastric instillates was constant (200 mosmole/l) the changes in their hydrogen ion concentrations (maximally from 0.01 to 100 mM) did not significantly affect pepsinogen secretion in anaesthetised rats. Solutions of 100 mM HCl, 100 mM NaCl and 150 mM sucrose all produced a similar stimulation of pepsinogen secretion. The results do not support the view that the gastric mucosa contains receptors sensitive to hydrogen ions regulating pepsinogen secretion under physiological conditions.

Animals↗

PubMed1978

Thermodynamics of the denaturation of pepsinogen by urea.

The denaturation of swine pepsinogen has been studied as a function of urea concentration, pH, and temperature. The unfolding of the protein by urea has been found to be fully reversible under different conditions of pH, temperature, and denaturant concentration. Kinetic experiments have shown that the transition shows two-state behavior at 25 degrees C in the pH range 6-8 covered in this study. Analysis of the equilibrium data obtained at 25 degrees C according to Tanford (Tanford, C. (1970), Adv. Protein Chem. 24, 1) and Pace (Pace, N.C. (1975), Crit. Rev. Biochem. 3, 1) leads to the conclusion that the free energy of stabilization of native pepsinogen, relative to the denatured state, under physiological conditions, is only 6-12 kcal mol-1. The temperature dependence of the equilibrium constant for the unfolding of pepsinogen by urea in the range 20-50 degrees C at pH 8.0 can be described by assigning the following values of thermodynamic parameters for the denaturation at 25 degrees C: deltaH=31.5 kcal mol-1; deltaS=105 cal deg-1 mol-1; and deltaCp=5215 cal deg-1 mol-1.

Animals↗

PubMed1979

Duodenal-ulcer disease associated with elevated serum pepsinogen I: an inherited autosomal dominant disorder.

To delineate genetic factors involved in the pathogenesis of duodenal ulcer, serum pepsinogen I levels were determined by radioimmunoassay in two large kindreds with multiple members affected with duodenal ulcer. An elevated serum immunoreactive pepsinogen I concentration (greater than 100 ng per milliliter) segregated as an autosomal dominant trait in these families. Furthermore, 10 of 11 patients with clinical ulcer disease in these families had hyperpepsinogenemia. An elevated serum pepsinogen I concentration appears to be a subclinical marker of the ulcer diathesis in families with this autosomal dominant form of peptic-ulcer disease.

Duodenal Ulcer↗

PubMed1975

Solubility fo fibrin clots in monochloroacetic acid. A reflection of serum pepsinogen levels.

Fibrin clots formed from normal plasma dissolve readily in 1% monochloroacetic acid at 37 C. However, if the clots are washed thoroughly before the acid is added, they are no longer soluble. The agent present in the serum which causes dissolution of the fibrin clot was isolated and identified as pepsinogen. Because of the low pH of monochloroacetic acid the pepsinogen is activated and the clots are digested, simulating the dispersion of a fibrin clot which occurs in the absence of fibrin-stabilizing factor (factor XIII). Because of its higher pH, urea will not activate pepsinogen and is therefore a better agent to screen factor XIII deficiencies.

Acetates↗

PubMed1979

Observations on ostertagiasis in young cattle over two grazing seasons with special reference to plasma pepsinogen levels.

The epidemiology of ostertagiasis in south west Scotland was studied in groups of cattle grazed through two successive grazing seasons separated by a period of winter housing. Towards the end of the first grazing season (September) the numbers of infective larvae (L3) on the pasture had increased to high levels (up to 24,000 L3 per kg) which resulted in high faecal egg counts, worm burdens, plasma pepsinogen levels and the occurrence of clinical ostertagiasis in the calves. By late spring (May) at the onset of the second grazing season, there was an almost complete mortality of the overwintered L3 on the pasture followed by the appearance of moderately high numbers of a new population of L3 in September (up to 9000 L3 per kg). The latter increase in the numbers of L3 was reflected by negligible faecal egg counts, low worm burdens and a moderate elevation of plasma pepsinogens in the second year animals. It therefore seems that although young cattle acquire a good immunity to Ostertagia ostertagi after one season at grass the small infections established in the early part of the second season are capable of contaminating the pasture to levels which could be dangerous for susceptible stock. An allergic reaction in the abomasal mucosa could be the basis of the elevated pepsinogens present in the second year animals.

Animals↗

PubMed1976

The pepsinogens of cat gastric mucosa and the pepsins derived from them.

Fundic mucosal extracts of the cat were examined by chromatography using DEAE-cellulose at pH 5.3. The peaks of proteolytic activity located by this method were shown to be heterogeneous on electrophoresis. By electrophoresis of individual homogenous chromatographic fractions 9 separate zones of proteolytic activity were detected. One zone did not migrate from the origin and is possibly a non-pepsinogen gastric protease. Simultaneous electrophoresis of pepsinogens and pepsins indicated that each pepsinogen gave rise to one pepsin. One zymogen gives rise to a pepsin active with the synthetic substrate acetyl-L-phenylalanyl-L-diiodotyrosine (APDT).

Animals↗

PubMed1978

Radioimmunological quantitation of human group-II pepsinogens.

A solid-phase sandwich radioimmunoassay was developed to quantitate human group-II pepsinogens in plasma. The test detected pepsinogen II in a concentration range of 0.25--64.0 ng/ml using sample volumes of 125 microliter. Purified group I pepsinogens showed no response up to concentrations of 100 microgram/ml. In apparently healthy donors, we observed mean plasma concentrations of 20.3 ng/ml (males) and of 15.5 ng/ml (females).

Antibodies↗

PubMed1979

Serum group I pepsinogens during prolonged infusion of pentagastrin and secretin in man.

Six 20- to 25-year-old healthy men were studied with an intravenous pentagastrin infusion in a dose of 6 micrograms/kg-h for 4.5 h. Four of these were also studied on separate days with an intravenous secretin infusion in a dose of 2 CU/kg-h for 4.5 h. Gastric juice was collected continuously for one 30-min period before and in 30-min periods throughout the infusion periods, and the gastric H+ and pepsin outputs were determined during the pentagastrin infusion only. Blood was drawn before, every 30 min throughout the infusion, and the next morning for determination of serum group I pepsinogens (PG I), serum gastrin, and plasma secretin. Pentagastrin evoked a sustained rise in gastric H+ and pepsin secretions, a more delayed and sustained increase in serum PG I in the four subjects with a normal pentagastrin-stimulated maximal gastric secretion, and a fall in serum PG I in the remaining two subjects with a low gastric secretion. Secretin also elicited a sustained elevation in serum PG I in all four examined, including one who showed a fall in serum PG I during pentagastrin infusion. It is proposed that pentagastrin may exert its stimulatory effect of pepsinogen synthesis subsequent to degranulation of the chief cells, whereas secretin may stimulate the pepsinogen synthesis more directly. Thus, the fall in serum PG I during pentagastrin infusion in the two subjects with low gastric secretion may possibly be due to a defective cellular storage of PG I in atrophic gastritis. Plasma secretin was not affected by gastric suction or by prolonged infusion of pentagastrin, whereas serum gastrin fell during secretion infusion accompanied by gastric suction.

Adult↗

PubMed1975

Synthesis and secretion of protein and pepsinogen by rabbit gastric mucosa in organ culture.

When maintained in organ culture, rabbit gastric mucosal biopsies incorporated [14tc]leucine into tissue protein and secreted labeled protein into culture medium steadily for 24 hr. Incorporation of radioactivity was abolished by cycloheximide. When examined by sodium dodecyl sulfate gel electrophoresis, dextran gel filtration, and ion exchange chromatography, 65 to 90% of macromolecular radioactivity secreted into culture medium migrated coincidentally with enzymatically assayed pepsinogen. Pepsin activity in cultured biopsies did not decrease during 24 hr of organ culture. Nevertheless, pepsin activity increased linearly in culture medium during this period. Acetylcholine markedly stimulated secretion of labeled protein and pepsinogen by cultured biopsies. In the presence of a subthreshold concentration (10(-10) M) of acetylcholine, pentagastrin, secretin, and the octapeptide of cholecystokinin, all stimulated protein secretion. Over-all incorporation of [14C]leucine into protein by cultured biopsies was stimulated by 10(-9) M pentagastrin. These results directly demonstrate: (1) synthesis and secretion of protein and pepsinogen by isolated gastric mucosa, (2) stimulation of gastric secretion of protein by acetylcholine and polypeptide hormones, and (3) stimulation of gastric synthesis of protein by pentagastrin.

Acetylcholine↗

PubMedDate not supplied

[Application of the automatic Edman procedure to establishing the primary structure of swine pepsinogen and its fragments].

The automatic Edman procedure was applied to elucidate N-terminal sequences of swine pepsinogen, pepsin, and the fragments of its degradation by BrCN, i. e. B-1 and B-5. A "Beckman" model 890 instrument was used in experiments. 50 amino acid residues were split off the pepsinogen molecule and identified and 55 amino acid residues-off the pepsin molecule by means of gas chromatography. A continuous N-terminal sequence of pepsinogen was 119 amino acids, in which the overlapping of the known peptide sequences with enzymic hydrolysers was taken into account. In B-1, B-4, B-5 fragments 22, 31 and 38, residues, respectively were analyzed with the sequencer.

Amino Acid Sequence↗

PubMed1977

On the apparent inhibition of intramolecular activation of pepsinogen by pepsin substrates.

Marciniszyn et al. (Marciniszyn, J., Huang, J. S. Hartsuch, J. A., Tang, J. (1976) J. Biol. Chem. 251, 7095-7102) have recently suggested an intermediate in the intramolecular activation of pepsinogen. As evidence, they showed apparent competitive inhibition of activation by globin, indication a pepsinogen-globin complex. Previous work had shown pepsinogen activation to occur very rapidly in the presence of high concentrations of hemoglobin, a very similar pepsin substrate (McPhie, P. (1974) Biochem. Biophys. Res. Commun. 56, 789-792). This contradiction has been resolved by a re-evaluation of the techniques used in the two investigations. The experimental conditions of Marciniszyn et al. Were inadequately defined to ensure denaturation of pepsin, a prerequisite of their method. A small decrease in pH, caused by the presence of extraneous protein, prevents this denaturation and leads to consistent underestimates of the rate of zymogen activation.

Animals↗