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At least 19 recordsLinked to original sources
PubMed1976

Degradation of blood group antigens in human colon ecosystems. I. In vitro production of ABH blood group-degrading enzymes by enteric bacteria.

Human feces contain enzymes produced by enteric bacteria that degrade the A, B, and H blood group antigens of gut mucin glycoproteins. We have studied their production in fecal cultures to determine if such cultures can be a source for enzyme purification and to explore how blood group antigen-degrading enzymes are adapted in individual human colon ecosystems. They were present in fecal cultures from each of 27 healthy subjects, including ABH nonsecretors. Heat-sensitive obligate anaerobes are their major source. From 39 to 85% of the total enzyme activity produced by growing cultures was extracellular. Commercial hog gastric mucin and salivary glycoproteins, including Lea saliva which lacks A, B, and H antigens, enhance production of A-, B-, and H-degrading activity in anaerobic fecal cultures irrespective of the glycoprotein's blood group specificity. There is evidence that the host's ABO blood type and secretor status affects the specificity of blood group-degrading enzymes produced by his fecal bacteria in vitro. Thus, fecal inocula from B secretors incubated with hog gastric mucin (A and H specificity) or with Lea saliva produced greater levels of B-degrading than A- or H-degrading activity, and inocula from A secretors in similar media produced greater levels of A-degrading than B- or H-degrading activity. Blood group-degrading enzymes produced in fecal cultures are glycosidases and not proteases. The B-degrading enzyme cleaves the B antigenic determinant alpha-D-galactose from the oligosaccharide side chains of mucin glycoproteins with B specificity. Anaerobic fecal cultures containing blood group substances are a feasible source for purifying blood group antigen-degrading enzymes. Prior adaptation to blood group antigens in the gut mucins of type A and type B secretors affects the specificity of the enzymes produced in vitro.

ABO Blood-Group System↗
PubMed1976

Autoregulatory system of insulin degradation in liver. II. Relationship between blood insulin levels and GSH-dependent insulin degrading activity in liver and blood.

An autoregulatory system of insulin degradation in the liver in which the rate of insulin metabolism changes in response to fluctuation in its blood levels, was investigated. In the plasma of rats and man in the absence of reduced glutathione (GSH), insulin degradation was not observed, but when a sufficient amount of reduced glutathione was added, the plasma did degrade insulin. This GSH-dependent insulin degrading activity in plasma was quite similar to that in liver in its nature. In rats, this GSH-dependent insulin degrading activity in the liver and plasma was fluctuated in response to fluctuation in the blood insulin levels, and the GSH-dependent insulin degrading activity in plasma was well correlated with that in the liver. Similarly, in man the GSH-dependent insulin degrading activity in plasma was changed in response to fluctuation in the blood insulin levels. In plasma under the physiologic conditions, there is an insufficient amount of reduced glutathione to elicit the insulin degrading activity, but in the liver there is a sufficient amount of reduced glutathione to manifest this activity. This evidence further supports the concept that an autoregulatory system of insulin degradation in the liver exists in man.

Animals↗
PubMed2026

Biotic and abiotic degradation of PHAs: mechanisms, environments, and potential applications of degradation products.

This review seeks to compile Polyhydroxyalkanoates (PHAs) degradation studies published over the past 20 years. It highlights the effect of physical properties, such as crystallinity and molecular weight, on the decomposition rate of these molecules. Both biotic processes, mediated by bacteria, fungi, and enzymes, as well as abiotic processes, such as hydrolysis and thermal degradation, are analyzed. A repertoire of diverse microorganisms, including their metabolic pathways and enzymes for PHA breakdown, is presented. Furthermore, this review presents the decomposition of PHAs in various environments, such as soil and seawater, highlighting their potential as a sustainable alternative. Finally, the resulting degradation products are described, emphasizing their potential applications in medicine and industry. Although degradation of PHAs has been extensively studied through these years, several knowledge gaps remain undisclosed, including the degradation of diverse polyester monomers. PHAs comprise numerous monomer compositions with variable properties, which present opportunities for different applications but pose a challenge in their degradation. The reader of this review can extract useful information for both the production of PHAs and their potential applications.

Biodegradation↗
PubMed1976

Degradation of cartilage proteoglycan by human leukocyte granule neutral proteases--a model of joint injury. II. Degradation of isolated bovine nasal cartilage proteoglycan.

Extracts of human peripheral blood polymorphonuclear leukocyte granules, and two purified proteases derived from such extracts, an elastase and a chymotrypsin-like enzyme, degrade isolated bovine nasal cartilage proteoglycan at neutral pH. Viscosity studies indicate that the leukocyte granule extracts lack hyaluronidase activity and that their degradative effect on proteoglycan at physiological pH is due entirely to proteolytic action. Sepharose 4B gel chromatography and SDS-polyacrylamide gel electrophoresis of proteoglycan fractions treated with leukocyte granule enzymes at pH 7.0 indicate that they degrade one of the proteoglycan link proteins, release a fragment from the hyaluronic acid-binding portion of the proteoglycan subunit core protein, and break down the remainder of the proteoglycan subunit molecule into peptide fragments with varying numbers of chondroitin sulfate chains. Immunodiffusion studies indicate that the antigenic determinants of the proteoglycan subunit core protein and the link proteins survive treatment with granule proteases. Similar degradation of human articular cartilage proteoglycan by granule neutral proteases can be presumed to occur, in view of the similarity of structure of human articular and bovine nasal cartilage proteoglycans. The release of granule enzymes in the course of neutrophil-mediated inflammation can thus result in the degradation of cartilage matrix proteoglycan, leading to cartilage destruction and joint injury.

Animals↗
PubMed2025

Effects of a novel Paraburkholderia phage IPK on the phenanthrene degradation efficiency of the PAH-degrading strain Paraburkholderia caledonica Bk.

Phages are a major cause of bacterial mortality, affecting bacterial diversity and ecosystem functioning. However, the impact of phage-host interactions in contaminated environments and their role in pollutant biodegradation have largely been overlooked. We isolated and characterized a novel phage that infects the PAH-degrading bacterium Paraburkholderia caledonica Bk from a polycyclic aromatic hydrocarbon (PAH)-contaminated soil and investigated the effect of different multiplicity of infection (MOI) ratios on the degradation efficiency of phenanthrene. The phage IPK is a temperate phage with a wide pH and temperature tolerance and a burst size of 80  PFU ml⁻1. The phage was classified as a member of the Caudoviricetes and is related to Pseudomonas and Burkholderia phages. However, its low intergenomic similarity indicates that it is a new species. Three auxiliary metabolic genes (AMGs) related to amino acid metabolism and to bacterial growth regulation were identified in the phage genome. The highest multiplicity of infection (MOI 10) showed a rapid recovery of the host density and greater phenanthrene degradation than MOIs ranging from 0.01 to 1. This work highlights the important role of phage-host interactions in modulating the efficiency of pollutant degradation, which could be a key for improving the establishment of inoculants in bioremediation processes.

Phenanthrenes↗
PubMed2025

The mhqPOD gene cluster in lignin-degrading Paenibacillus sp. B2 encodes a pathway for the degradation of lignin-derived 5,5'-di(dehydrovanillic acid) (DDVA).

Lignin-degrading bacteria Paenibacillus sp. B2, Agrobacterium sp. B1, and Ochrobactrum sp. each contain mhqO genes encoding ring cleavage dioxygenase enzymes whose biochemical function is unknown. Each of these strains was found to degrade the biphenyl-containing lignin fragment 5,5'-di(dehydrovanillic acid) (DDVA) on solid media. An operon of five mhq genes in Paenibacillus sp. B2 was analysed via gene expression using quantitative PCR, and all five genes were highly induced (400-1000-fold overexpression) by the presence of DDVA. Recombinant azoreductase MhqP was found to demethylate DDVA to its monodemethylated derivative. Hence, these genes are proposed to be responsible for DDVA degradation, via a pathway involving the same biochemical steps as that studied in Sphingobium lignivorans SYK-6, but using several unrelated genes. Decarboxylation of later pathway intermediate 5-carboxyvanillic acid in Paenibacillus sp. B2 is proposed to be catalysed by decarboxylase UbiD, whose gene is also upregulated in the presence of DDVA. Degradation of the other fragment 4-carboxy-2-hydroxypentadienoic acid is proposed to occur via hydratase UxuA, whose gene is also upregulated by DDVA, and 4-hydroxy-4-methyl-2-oxoglutarate aldolase.

Paenibacillus↗
PubMed1977

[Isolation and characterization of Proteus mirabilis mutants deficient in DNA degradation: function of endonuclease I in postmortem DNA degradation].

DNase deficient mutants of Proteus mirabilis selected for reduced toluene induced DNA degradation were isolated. Their defect in DNA degradation was shown not only after treatment by toluene but also in crude extracts after cell disintegration by ultrasonic and in untreated starved cultures. The degradation mutants behave just as the wild type with respect ot their in vivo functions proffed. The results inidcate that the affected DNase does not have an essential function in vivo but acts in postmortem DNA degradation. Probably the DNase in question concerns the endonuclease I of P. mirabilis described by Goebel and Helinski (1971 a, b).

Cell-Free System↗
PubMed1976

Starch degradation by the mould Trichoderma viride. I. The mechanism of starch degradation.

The mechanism of starch degradation by the fungus Trichoderma viride was studied in strain CBS 354.44, which utilizes glucose, starch and dextrins but is unable to assimilate maltose. It was shown that the amylolytic enzyme system is completely extracellular, equally well induced by starch, amylose or amylopectin and that it consists mainly of enzymes of the glucoamylase type which yield glucose as the main product of starch hydrolysis. Small amounts of alpha-amylase are produced also. The enzymes produced in starch cultures degrade starch, amylose and amylopectin equally well. Enzyme synthesis in starch media takes place to a considerable extent after exhaustion of the carbon source when maximum growth has been attained. Low-molecular dextrins are degraded by extracellular enzymes of the glucoamylase type. These enzymes are produced in media containing starch or dextrins. Maltotriose is consumed for only one third leaving maltose in the culture filtrate. Maltose is hardly attacked and hardly induces any amylolytic enzyme activity. No stable alpha-glucosidase appears to be produced.

Amylases↗
PubMed1979

Biosynthesis and degradation of prolactin in the rat anterior pituitary gland. Time course of incorporation of label in vitro and evidence for rapid degradation.

Biosynthesis of prolactin was studied in anterior pituitary glands from female rats, incubated in vitro. In this system [3H]leucine was incorporated into pituitary proteins, including somatotropin (growth hormone) and prolactin. The rate of uptake of label into prolactin (and to a lesser extent into total protein) slowed considerably during the first 2 h of incubation, although the rate of uptake into somatotropin was constant for 8 h. The most probable explanation for this apparent decrease in the rate of prolactin synthesis is degradation of prolactin in the gland. Degradation of this hormone was also demonstrated by incubating prelabelled pituitaries in unlabelled medium and following the content of labelled prolactin, and by studying the hormonal content of pituitary glands (by radioimmunoassay) before and after incubation. Degradation of prolactin appears to be much more rapid than that of somatotropin, and may represent a physiological mechanism whereby over-accumulation of prolactin is prevented when secretion of the hormone has been rapidly switched off.

Animals↗
PubMed1976

Kinetics and mechanism of degradation of some 5-allylbarbituric acid derivatives. Part 3: Kinetics of solvolysis of major intermediates of 5.5-diallylbarbituric acid degradation.

Solvolysis of N-diallylacetylurea and 5.5-diallylmalonuric acid was investigated in the pH range ca. 8--12 by means of spectrophotometric and t.l.c. methods. Their log k--pH profiles were constructed from the experimental results obtained by degradation at 70 degrees C. Therefore, specific catalytic rate constants and pKa's were derived. The kinetic mechanism of N-diallylacetylurea solvolysis, resulting among other things from the so-called kinetic salt effect, depends on hydroxyl-ion attack on its undissociated and monoanionic forms. However, the degradation of alpha.alpha-diallylmalonuric acid in the pH range 10--12 is an example of specific base catalysis which can be explained by hydroxyl-ion attack on its monoanionic species. The degradation of alpha.alpha-diallylmalonuric acid below pH=10 does not follow a theoretical equation postulated, because the spectrophotometric method does not allow monitoring the formation of N-diallylacetylurea in the presence of the above acid. Thin-layer chromatography was used to check different pathways of transformations of the intermediate studies.

Allyl Compounds↗
PubMed1979

[Degradation and biosynthesis of L-phenylalanine by chloridazon-degrading bacteria].

Incubating chloridazon-degrading bacteria with L-phenylalanine leads to the accumulation of L-2,3-dihydroxyphenylalanine, o-tyrosine and m-tyrosine in the medium. Incubating the bacteria with N-acetyl-L-phenylalanine leads to N-acetyl-(2,3-dihydroxyphenyl)alanine. Using phenylacetic acid as substrate leads to the accumulation of malonic acid. The products are isolated by gel chromatography and high performance liquid chromatography. 2,3-Dihydroxy-L-phenylalanine is attacked by a catechol 2,3-dioxygenase in the presence of Fe2. An unstable yellow compound is formed in this reaction. This meta-cleavage-product is again cleaved by a hydrolase, leading to aspartic acid and 4-hydroxy-2-oxovaleric acid. Both products were isolated fromthe reaction buffer by amino acid analysis and high performance liquid chromatography. The dioxygenase and hydrolase were partially purified and characterized. A new degradation pathway for phenylalanine is discussed and compared with known pathways. The enzymes chorismate mutase, prephenate dehydratase and prephenate dehydrogenase are characterized and inhibition as well as repression are investigated. Only prephenate dehydrogenase is inhibited by phenylalanine, tyrosine and tryptophane. Chorismate mutase is repressed by phenylalanine, prephenate dehydrogenase by phenylalanine and tyrosine. Prephenate dehydratase is not repressed by aromatic amino acids. Regulation of aromatic amino acid biosynthesis in connection with phenylalanine degradation is discussed.

Bacteria↗
PubMedDate not supplied

[Degradation of antipyrin by pyrazon-degrading bacteria (author's transl)].

Bacteria with the ability to grow on pyrazon as sole source of carbon were isolated from soil. They also are able to grow on antipyrin. Then three metabolites of antipyrin can be isolated from the culture fluid which were identified as 2,3-dimethyl-1-(cis-2,3-dihydro-2,3-dihydroxy-4,6-cyclohexadiene-1-yl)-pyrazolone (5) (I), as 2,3-dimethyl-1-(2,3-dihydroxyphenyl)-pyrazolone (5) (II) and as 2,3-dimethyl-pyrazolone (5) (III), respectively. Compound I and II were used as substrates for enzyme studies. A dioxygenase catalyzes the enzymatic conversion of antipyrin into compound I. In the presence of NAD as cosubstrate compound I is transformed into compound II by a dehydrogenase. A pure preparation of metapyrocatechase from pyrazon-degrading bacteria converts compound II into the dephenylated heterocyclic moiety of antipyrin (III) and into 2-pyrone-6-carboxylic acid. Based on the results of the enzymatic studies a pathway for the degradation of antipyrin is proposed.

Antipyrine↗
PubMed1978

Degradation of human fibrinogen by plasmin: isolation and partial characterization of an early degradation product.

The incubation of human fibrinogen with plasmin gives rise to an early degradation product with a molecular weight of 63,000, calculated by polyacrylamide-gel electrophoresis sodium dodecyl sulfate (PAGE-SDS); this product is resistant to the action of the plasmin for short incubation times and represents 1 +/- 0.2% of the original quantity of fibrinogen. The fragment was isolated from the incubated mixture by gel filtration and has a no-identity reaction with fibrinogen fragment D against fibrinogen fragments D antiserum. The reduction gives rise to three polypeptidic chains with molecular weights of 36,000, 17,000 and 10,000 (calculated by PAGE-SDS). Study of the carbohydrate content of these polypeptidic chains from the reduced 63,000 MW fragment indicates that there is only one electrophoretic region which contains periodic acid-Schiff (PAS) positive material. As the 63,000 MW fragment has a reaction against fibrinogen fragment D antiserum and also contains PAS positive material, according to Pepper and co-workers, it can be taken to arise from the HOOC-terminal region of fibrinogen.

Chromatography, Gel↗
PubMed1979

Chemical and enzymic degradations of nucleoside mono- and diphosphate sugars. I. Determination of the degradation rate during the glycosyltransferase assays.

In incorporation experiments used for the determination of glycosyltransferase activities, we demonstrated that the nucleoside diphosphate sugars are decomposed in three different ways: 1, transfer of the monosaccharide to acceptor molecule, catalyzed by glycosyltransferases; 2, degradation of the glycosyl nucleotides by nucleotide pyrophosphatase into monosaccharide 1-phosphates which are further hydrolyzed into free monosaccharides by phosphatases; 3, chemical decomposition of UDP-D-[14C]Gal; UDP-D-[14C]Glc and UDP-D-[14C]GlcUA into 1,2-cyclic phosphate derivatives of the corresponding monosaccharide. All the breakdown products of the nucleoside mono- and diphosphate sugars which are obtained during the incorporation experiments may be separated by paper chromatography and their amounts may be determined. Galactosyltransferase assays on human and rat serum have shown that the three different ways of decomposition of the nucleoside diphosphate sugars are dependent mostly on the concentration of divalent cations (Mn2+, Mg2+). Inhibition of the nucleotide pyrophosphatase activity is obtained with low concentrations of UMP, but increasing concentrations of UMP inhibit also the galactosyltransferase activity and consequently enhance the formation of galactose 1,2-monophosphate. A partial elimination of the nucleotide pyrophosphatase activity was achieved by the addition of increasing concentrations of UDP-D-Gal. These results demonstrate that the determination of glycosyltransferase activities in tissues and in biological fluids is not possible without a concomitant determination of the nucleotide pyrophosphatase activity present in the assay.

Adult↗