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At least 19 recordsLinked to original sources
PubMed1989

Lipolytic enzymes of the digestive organs of the crown-of-thorns starfish (Acanthaster planci): comparison of the stomach and pyloric caeca.

1. Stomach and pyloric caeca homogenates from the crown-of-thorns starfish hydrolysed p-nitrophenyl esters, alpha-naphthyl esters, cholesteryl oleate and tributyrin. The pyloric caeca contained the highest activities. 2. The p-nitrophenyl acetate hydrolytic activity eluted at 0.23 M NaCl on ion exchange chromatography while the p-nitrophenyl palmitate hydrolytic activity eluted between 0.2 and 1.0 M NaCl. 3. Polyacrylamide gel zymograms for alpha-naphthyl acetate hydrolytic activity revealed one major band and several minor bands of activity for both tissues. 4. Isoelectric focusing zymograms revealed one major band with a pI = 4.2 for both tissues, with an additional band at pI = 3.5 for pyloric caeca. 5. The pyloric caeca contained twice as much lipid as the stomach. Lipid extracts contained mixtures of steroids and steroid-esters; a cholesterol-like sterol was tentatively identified.

Animals↗
PubMed1995

Catalytic site studies on tuna (Thunnus albacares) pyloric caeca aminopeptidase.

Tuna pyloric caeca aminopeptidase (tAP) is a glycosylated zinc-metalloenzyme containing apparently two identical subunits. The enzyme is reversibly inhibited in a time-dependent manner by amastatin. Slow development of tAP inhibition by this inhibitor could be demonstrated. Dissociation of the complex of tAP with amastatin is also slow. Two molar equivalents of the inhibitor are bound by the enzyme suggesting the presence of one catalytic site in each subunit. Chemical modification of tAP with 1-cyclohexyl-3-(2-morpholinoethyl) carbonyl-metho-p-toluene sulfonate and N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinone revealed the presence of essential acidic amino acid residues probably located at the active site. Compatible with the presence of arginine and tyrosine residues at the catalytic site of most metalloproteinases, tAP is reversibly inhibited by phenylglyoxal and inactivated by tetranitromethane in a time-dependent fashion. The rate of inhibition by these modifiers could be significantly decreased if the enzyme was previously treated with amastatin suggesting that the modified amino acid residues are located at the catalytic site. Diethylpyrocarbonate did not affect the activity of both native and zinc-depleted tAP suggesting that histidine is not involved in the zinc-ligand formation.

Aminopeptidases↗
PubMed1982

Effects of oestradiol-17 beta on the synthesis of RNA, proteins and lipids in the pyloric caeca of the female starfish Asterias rubens.

1. The effects of oestradiol-17 beta on processes of synthesis in the pyloric caeca of female Asterias rubens were studied. 2. In vitro treatment with 2.5 X 10(-7) M oestradiol-17 beta resulted in significantly higher RNA levels. 3. In vivo treatment with oestradiol-17 beta resulted in higher lipid levels in the pyloric caeca, but RNA levels, protein levels and the incorporation of 6-[14C]orotic acid, L-leucine-[14C] and sodium 1-[14C] acetate into RNA, proteins and lipids, respectively were not affected, neither were the indices of the gonads and pyloric caeca.

Animals↗
PubMed1986

The glutathione S-transferase activity in the pyloric caeca of rainbow trout, Salmo gairdneri.

Pyloric caeca of trout contain 1.9 mmol GSH/kg tissue. Cytosolic glutathione S-transferase activity with 1-chloro-2,4-dinitrobenzene as substrate is 0.06 mmol/min/g protein. Cholate (3.3 mM) inhibits cytosolic transferase activity by 55% at pH 6.6 and by 4% at pH 7.4. The transferases do not bind 8-anilino-1-naphthalene sulphonate at pH 7.4. The cytosolic transferases are inactivated progressively by 1-chloro-2,4-dinitrobenzene, 50% of their activity being lost in 5.0 min. A minority of the activity does not bind to a glutathione-affinity matrix. At pH 6.6 its apparent Michaelis constants for GSH and 1-chloro-2,4-dinitrobenzene are 0.88 and 9.1 mM respectively. The rest of the activity is eluted from the affinity matrix as a single peak. Its apparent Michaelis constants for GSH and 1-chloro-2,4-dinitrobenzene are 0.33 and 2.9 mM respectively. Its subunit Mr is 22.4 kDa.

Animals↗
PubMed1994

Purification and characterization of an aminopeptidase from tuna (Thunnus albacares) pyloric caeca.

An aminopeptidase was purified from a water soluble fraction of tuna pyloric caeca by heat treatment, Zn2+ fractionation, ion exchange on a DEAE cellulose column, gel filtration on Fractogel TSK-55, and immobilized metal ion affinity chromatography (IMAC) on IDA(Cu2+/Zn2+)-Sepharose 6B. The molecular mass of the enzyme was estimated to be 150,000 on Sephacryl S-300 HR, and was found to be near 72,000 by SDS-PAGE. The aminopeptidase, which is a glycoprotein rich in acidic amino acids, is optimally active at pH 8.8 and 65 degrees C. The enzyme activity was not affected by Mg2+, Zn2+, Ca2+, Mn2+, Co2+, PMSF, iPr2FP, 4-hydroxymercuribenzoic acid, iodoacetamide, puromycin, and cysteine but it was strongly inhibited by metal chelators (EDTA and o-phenanthroline), amastatin, Hg2+, Cd2+, and Cu2+. The enzyme was also inhibited by some L-amino acids. Kinetic parameters of the enzyme were determined with some aminoacyl-p-nitroanilides and aminoacyl-beta-naphthylamides. L-Alanine-p-nitroanilide and L-alanine-beta-naphthylamide were hydrolysed most rapidly while the highest hydrolytic coefficient (kcat/Km) value was obtained with L-methionine-p-nitroanilide. The apoaminopeptidase was prepared and reconstitution of an active enzyme was carried out using metal chelating interaction chromatography on an IDA-Sepharose 6B column charged with a metal ion. Full activity was restored with Zn2+, Co2+, Cu2+ and Al3+. Zn(2+)-Enzyme was the most thermostable form of the aminopeptidase. Reversal inhibition by Cu2+ and Cd2+ was also examined. When the aminopeptidase was partially deglycosylated by a treatment with N-glycosidase F some of its physical properties differed from that of the native enzyme: its electrophoretic mobility was reduced and its stability to denaturation by SDS and by ionic strength were lower than those of the untreated enzyme. All together, our results indicate that the tuna pyloric caeca aminopeptidase is distinct from the peptide hydrolases characterized in the literature.

Amino Acids↗
PubMed1982

Changes in the activities of selected enzymes of intermediary metabolism in the pyloric caeca and ovaries of asterias rubens during the annual reproductive cycle.

1. Activities of several enzymes of glycolysis, glycerolphosphate cycle, TCA-cycle, beta-oxidation and pentose phosphate cycle were determined in pyloric caeca and ovaries of Asterias rubens during the reproductive cycle. 2. In the ovaries activities of CS and LDH were significantly decreased during ovarian stages 3 and 4, and those of GDH and GAPDH during stage 3 and 4, respectively. 3. In the pyloric caeca activities of GAPDH and LDH were lower in stage 4 and that of GDH in stage 3, whereas those of G6PDH and HOAD were increased in stage 3. 4. Changes observed in enzyme activities are discussed in relation to the reproductive cycle and to the multiple function of the pyloric caeca.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1986

Aristotle revisited: the function of pyloric caeca in fish.

The function of the pyloric caeca of fish has been uncertain since their detailed description in 345 B.C. by Aristotle. He suggested three hypotheses about their function: "to store up the food," "putrify it up," and "concoct it" (i.e., storage, fermentation, and digestion). Our results for trout, cod, largemouth bass, and striped bass support the third but not the first or second of Aristotle's theories. In all four species, the caeca prove to be a major site of sugar, amino acid, and dipeptide uptake, contributing more uptake than the entire remaining alimentary tract in trout and cod. Caecal brush-border membranes contain hydrolytic enzymes. X-ray plates taken at various times after trout had ingested radioopaque marker, and observations of trout fed blue dye plus glass beads of graded sizes, show that caeca fill and empty of food with the same time course as proximal intestine. Thus, whereas the caeca of mammals and birds serve as fermentation chambers, fish caeca are an adaptation to increase gut surface area.

Animals↗
PubMedDate not supplied

[Preparation and properties of trypsin from the pyloric caeca of Pacific Ocean salmon].

Trypsin from pyloric caeca of Pacific salmon was purified by affinity chromatography of the water extract on hexamethylenediamine-glycidylmethacrylate-cellulose. A protein band with a molecular weight of 22.5 kDa was found on SDS-electrophoresis in PAG. The protein band was homogeneous according to isoelectrofocusing in PAG (pI 4.0). The amino acid composition of the enzyme is typical of trypsin anionic forms; the major difference from the cationic forms is the lower content of lysine. The differences in properties caused by change of the enzyme molecule charge are similar to those observed in cationic trypsin when the lysine epsilon-amino groups of the latter are modified (change of pI, shift of the pH-optimum towards basic values, increase of stability to autolysis). Some natural trypsin inhibitors of the different origin suppressed the enzyme activity of trypsin from Pacific salmon in typical stoichiometric ratios. An unusual interaction of the enzyme with the specific inhibitor N-L-tosyl-L-lysine chloromethyl ketone was observed.

Amino Acids↗
PubMed1994

NADPH-, NADH- and cumene hydroperoxide-dependent metabolism of benzo[a]pyrene by pyloric caeca microsomes of the sea star Asterias rubens L. (Echinodermata: Asteroidea).

1. Benzo[a]pyrene (BaP) metabolism was studied in microsomes of the pyloric caeca (main digestive tissue and site of P450) of the echinoderm sea star (starfish) Asterias rubens. 2. NADPH-dependent metabolism of BaP produced phenols (36% of total metabolism), quinones (19%), dihydrodiols (25%) and putative protein adducts (20%). 3. NADH-dependent rates of BaP metabolism were approximately twice those found for NADPH-dependent metabolism, and metabolite formation was shifted towards dihydrodiols and quinones. 4. Cumene hydroperoxide (CHP)-dependent rates of BaP metabolism were also higher than NADPH-dependent rates by a factor of six for quinone and putative protein adduct production, and by a factor of four for phenol and dihydrodiol production. 5. Microsomal rates of BaP metabolism in BaP-exposed sea stars appeared to be elevated more in the case of NADPH-dependent than for CHP-dependent metabolism (respectively, increases of 130 and 41%), indicating the induction of forms of P450 preferentially catalysing NADPH-dependent metabolism. 6. 1,1,1-Trichloropropene-2,3-oxide (TCPO) inhibited dihydrodiol formation from both NADPH- and CHP-dependent BaP metabolism, indicating the involvement of epoxide hydratase in BaP metabolism. 7. Incubations of pyloric caeca microsomes with BaP and a superoxide anion radical-generating system (xanthine/xanthine oxidase) produced putative protein adducts but no free metabolites.

Animals↗
PubMed1992

Sex steroid levels in the testes, ovaries, and pyloric caeca during gametogenesis in the sea star Asterias vulgaris.

The concentrations of progesterone, testosterone, and estradiol were determined via radioimmunoassay in testes, ovaries, and pyloric caeca of the sea star Asterias vulgaris during one complete and two partial gametogenic cycles. These compounds were found in all tissues examined and were present in quantities similar to those reported previously in other echinoderms and in vertebrates. Testes and ovaries exhibited annual growth cycles during which testicular and ovarian mass increased up to 100-fold as gametes were produced and stored until spawning. Pyloric caecal mass varied during the annual reproductive season; however, no seasonal trends were apparent. In the testes, sex steroid levels were highest at the onset of spermatogenesis. Transient increases in the levels of estradiol coincided with spermatogonial mitotic proliferation. Transient increases in the levels of testosterone and progesterone in the testes coincided with spermatogenic column formation and with spermiogenesis, respectively. In the ovaries, estradiol and testosterone levels were highest at the onset of oogenesis while progesterone levels did not change significantly throughout the annual gametogenic cycle. Male and female pyloric caeca exhibited similar seasonal variations in levels of sex steroids as compared with the gonads. It is hypothesized that transient increases in the levels of sex steroids during gametogenesis may serve as endogenous modulators of reproduction.

Animals↗
PubMed1981

Studies on proteinases from the digestive organs of sardine. I. Purification and characterization of three alkaline proteinases from the pyloric caeca.

Three alkaline proteinases designated I, II and III are found in the pyloric caeca of sardine and isolated by (NH4)2SO4 fractionation, DEAE-cellulose chromatography and gel filtration on Sephadex G-100. The final preparations were judged homogeneous by multiple criteria. The molecular weights of the enzymes I, II and III were determined by the sedimentation equilibrium method to be 22 900, 28 700 and 27 000, respectively. The isoelectric points were 5.45, 5.30 and 4.85, and the sedimentation coefficients (S0 20, w) were 2.91, 3.06 and 2.94, respectively. Enzymes II and III had similar amino acid compositions which were different from that of enzyme I, especially in the content of lysine, valine and tyrosine. All the enzymes belonged to a group of serine proteases. Enzymes II and III were found to be an anionic alpha-chymotrypsin-like enzymme and an anionic trypsin-like enzyme, respectively. Although these fish enzymes had properties in common with those of bovine pancreatic cationic trypsin and chymotrypsin, they are distinctly different in their optimum pH, pH stability, net charge and immunological properties.

Amino Acids↗
PubMed1977

Morphological and cytochemical studies on the secretory granules of the pyloric caeca of the starfish, Asterias amurensis.

A fraction rich in secretory granules was prepared from the pyloric caeca of Asterias amurensis by sucrose density gradient centrifugation. The freshly prepared fraction exhibited no casein-hydrolyzing activity, but showed nine times as much specific activity as that of tissue homogenates after incubation at 37 degrees C for thirty minutes. Electron microscopy showed that the secretory granules were membrane-bound granules measuring 0.5-2.0 mu in diameter and contained dense and/or light amorphous substances.

Animals↗
PubMedDate not supplied

Purification and characterization of two chymotrypsin-like proteases from the pyloric caeca of rainbow trout (Oncorhynchus mykiss).

1. Two chymotrypsins, called chymotrypsin I and II, were purified from the pyloric caeca of rainbow trout, by (NH4)2SO4 fractionation, hydrophobic interaction chromatography (phenyl-Sepharose) and ion-exchange chromatography (DEAE-Sepharose). 2. The approximate molecular weights of chymotrypsin I and II were 28,200 (+/- 1200) and 28,800 (+/- 900), respectively, as determined by SDS-PAGE and their isoelectric points were about 5. 3. The pH optima of the enzymes were centered around nine, when assayed for succinyl-L-Ala-L-Ala-L-Pro-L-Phe-p-nitroanilide (Suc-AAPF-NA) as substrate and both enzymes were unstable at pH values below 5. 4. The amidase activity of both enzymes increased with temperature up to about 55 degrees C. Chymotrypsin I was found to be more heat stable than chymotrypsin II, an effect most likely explained by stronger calcium binding of the former. 5. The trout chymotrypsins were significantly more active than bovine alpha-chymotrypsin when assayed against Suc-AAPF-NA at 25 degrees C and casein at low temperatures (10-20 degrees C), indicating an adaptation of the activities of the trout chymotrypsins to the habitation temperatures of the fish.

Amino Acid Sequence↗
PubMed1991

Optimization and scale up of the adsorption fractionation of cod pyloric caeca deoxyribonuclease using axial and radial flow columns.

The key step in the purification of a deoxyribonuclease (DNase) from extracts of cod (Gadus morhua L.) pyloric caeca, is the selective retention of the enzyme by anion exchange chromatography. The cod DNase purification on Q-Sepharose Fast Flow (Pharmacia) was optimized, using a 60 ml fixed-bed column. In combination with titration curve analysis, we have screened the effect of buffer pHs, feed conductivity and protein loading, on the product recovery and purity. We have developed elution conditions which allow effective separation of the cod DNase from bounded impurities, such as proteinases and nucleic acids. Low levels of these impurities were regarded as essential for the desired product quality. The optimum resolution and maximum purification (ca. 20-fold increase in specific activity) of DNase, was, however, achieved at low protein loading (2.6 mg ml-1 gel), corresponding to less than 4% of the dynamic bed capacity. Scale-up to a 2.5 l pilot scale column (axial flow) and a 0.25 l radial flow column showed that the separation and yield obtained at laboratory scale was retained, and was independent of column geometry and bed height. The implications for a production scale scenario of 100 g of fractionated protein, are also discussed, as well as process hygiene. The optimization described herein adds further knowledge to the treatment of fish waste and the downstream processing of valuable biochemicals from marine raw material.

Adsorption↗
PubMed1979

An electron microscopic study of lipid absorption in the pyloric caeca of rainbow trout (Salmo gairdnerii) fed wax ester--rich zooplankton.

Rainbow trout were killed 4 and 18 h after being fed wax ester-rich marine zooplankton and the absorptive epithelium of the pyloric caeca examined by electron microscopy. Numerous osmiophilic drops were seen in the lamina propria underlying the epithelium of fish killed at both times, but these drops were only abundant within columnar epithelial cells of fish killed 4 h after feeding. Pinocytotic profiles were not common at the luminal plasma membranes, nor were osmiophilic droplets seen in the terminal web area between the luminal plasma membrane and the extensive smooth endoplasmic reticulum. Numerous osmiophilic droplets, 30--100 nm in diameter, were present in the cisternae of the smooth endoplasmic reticulum with up to five separate droplets per individual cisterna. Columnar epithelial cells also contained up to 100 large osmiophilic drops ("conglomerates") which tended to be concentrated in the supranuclear (Golgi) regions. The conglomerates were 250--1200 nm in diameter and were themselves made up of smaller droplets 30--400 nm in diameter. Conglomerates were present both within intracellular membranes and free in the cytoplasm. Osmiophilic droplets in the intercellular spaces and lamina propria were similar in size to individual droplets within conglomerates. We conclude that triacylglycerols are elaborated in the smooth endoplasmic reticulum, transferred to and processed in the Golgi region and finally discharged serosally as chylomicron-like particles of not greater than 400 nm diameter.

Animals↗
PubMed1992

Some peptide-like colocalizations in endocrine cells of the pyloric caeca and the intestine of Oncorhynchus mykiss (Teleostei).

The coexistence of immunoreactivities to cholecystokinin, glucagon, glucagon-like peptide 1, salmon pancreatic polypeptide, neuropeptide tyrosine, and peptide tyrosine tyrosine was studied immunocytochemically, revealing for the first time in fish intestine the existence in the same cell of immunoreactivities to cholecystokinin-glucagon/glucagon-like peptide 1, cholecystokinin-salmon pancreatic polypeptide, glucagon/glucagon-like peptide 1-salmon pancreatic polypeptide, glucagon/glucagon-like peptide 1-neuropeptide tyrosine, salmon pancreatic polypeptide tyrosine tyrosine, and glucagon/glucagon-like peptide 1-peptide tyrosine tyrosine. Colocalization of cholecystokinin-salmon pancreatic polypeptide was observed only in the pyloric caeca of the rainbow trout Oncorhynchus mykiss, while the other colocalizations also occurred in proximal and middle intestinal segments. In all cases, endocrine cells immunoreactive to only one of the paired antisera were detected except for anti-glucagon and anti-glucagon-like peptide 1, which always immunostained the same cells.

Animals↗
PubMed1994

Soybean trypsin inhibitors in diets for Atlantic salmon (Salmo salar, L): effects on nutrient digestibilities and trypsin in pyloric caeca homogenate and intestinal content.

Atlantic salmon (Salmo salar, L), 180 g, were fed diets containing a crude trypsin inhibitor from soybean at five levels. The five levels resulted in trypsin inhibitor activities (TIA) corresponding to an inclusion of 0 to about 100% commercial soybean meal. Digestibility of protein and fat, weight gain and trypsin activity in intestinal content were significantly reduced with increasing dietary TIA. The response curves for nutrient digestibility and growth indicated that the Atlantic salmon were able to compensate for a certain TIA, equivalent to about 5 mg bovine trypsin inhibited per g feed. This compensation seemed to be due to increased trypsin secretion as suggested by the values for total content of trypsin in the pyloric caeca homogenate. At the highest level of TIA, the pancreatic capacity of trypsin synthesis seemed to be exhausted.

Animal Nutritional Physiological Phenomena↗