Biomedical subjects

H Hippe

Publications and source records attributed to H Hippe.

8 recordsLinked to original sources

PubMed1991

Creatinine deiminase (EC 3.5.4.21) from bacterium BN11: purification, properties and applicability in a serum/urine creatinine assay.

Creatinine deiminase (EC 3.5.4.21) from the anaerobic microorganism BN11 has been purified to homogeneity by ammonium sulfate fractionation, gel filtration on Sephacryl-S-300 superfine and chromatography on DEAE-Sepharose C1 6B. The final enzyme preparation had a specific activity of 78 units per mg protein. Analysis of creatinine deiminase by polyacrylamide gradient gel electrophoresis and fast-flow-liquid-chromatography gave a relative molecular mass of 285 kDa and 288 kDa, respectively. By treatment with sodium dodecylsulfate and 2-mercaptoethanol creatinine deiminase was dissociated yielding one polypeptide with a relative molecular mass of 47.5 kDa. The enzyme was entirely specific for creatinine and showed a Km value of 0.15 mM. Creatinine deiminase was used to determine the concentration of creatinine in serum and urine using a manual method and an automated system.

Aminohydrolases↗

PubMed1991

Lithotrophic growth and hydrogen metabolism by Clostridium magnum.

Clostridium magnum, originally described as a non-autotrophic homoacetogenic bacterium, was found to be able to grow with H2/CO2, formate, or methanol with stoichiometric acetate formation, provided that the growth medium contained at least 0.025% (w/v) yeast extract. Hydrogen was also formed as a byproduct of glucose fermentation, and was consumed again after glucose consumption. Hydrogen formation from glucose was independent of growth conditions and reached similar maximal concentrations in mineral media with or without ammonia added as well as in non-growing cultures or in the presence of carbon monoxide.

Carbon Dioxide↗

PubMed1990

Production of novel pullulanases at high concentrations by two newly isolated thermophilic clostridia.

Two thermophilic bacteria, which are capable of growing on starch at 60-70 degrees C under anaerobic conditions, were isolated from a sugar refinery in Uelzen and from Solar lake in Israel. On the basis of their physiological characteristics they were identified as Clostridium thermohydrosulfuricum Uel 1 and C. thermohydrosulfuricum Sol 1, respectively. The product pattern of glucose polymer hydrolysis showed that both strains secreted enzymes that possess amylolytic and pullulytic activities. The major product formed was maltose. In addition, alpha-glucosidase activity could be detected in the supernatants of Uel 1 strain. Compared to most anaerobes investigated these isolates secreted extremely high concentrations of pullulanases in batch culture. Up to 85% of the total enzyme synthesized was detected in the culture fluid. Unlike the pullulanases of type I, which can only attack the alpha-1,6-glycosidic linkages, the pullulanases of both clostridial strains were also capable of hydrolyzing alpha-1,4-linkages. The enzyme system of both bacteria was found to be highly thermoactive; optimal activity was detected at pH 5.0 and 85 degrees C. Even at 95 degrees C and without the addition of metal ions still 15% to 25% of enzymatic activity was detectable.

Clostridium↗

PubMed1987

Screening for plasmids in the genus Clostridium.

A plasmid screening was performed on 150 strains out of 75 clostridial species using a modification of the alkaline-lysis procedure. In 26 strains representing 21 species one or more plasmid bands were detected ranging in size from 3 to more than 100 kilobase pairs. Clostridium aceticum proved to contain a single small plasmid (pCA1) of 5.4 kbp as revealed by restriction analysis and electron microscopy. A physical map of pCA1 has been constructed. Spontaneous mutants of C. aceticum defective in autotrophic growth have been isolated. No direct correlation between plasmid content and autotrophy could be found.

Centrifugation, Density Gradient↗

PubMed1979

Utilization of trimethylamine and other N-methyl compounds for growth and methane formation by Methanosarcina barkeri.

A number of N-methyl compounds, including several methylamines, creatine, sarcosine, choline, and betaine, were readily fermented by enrichment cultures yielding methane as a major product. Methylamine, dimethylamine, trimethylamine, and ethyldimethylamine were fermented by pure cultures of Methanosarcina barkeri; except for ethyldimethylamine, these amines are considered important substrates of this methanogenic microorganism. Creatine, sarcosine, choline, and betaine were fermented to methane only by mixed cultures. During growth of M. barkeri on methyl-, dimethyl-, or trimethylamine, methanol was not excreted into the medium. The fermentation of trimethylamine gave rise to an intermediary accumulation of methyl- and dimethylamine in the medium. An accumulation of methylamine during the fermentation of dimethylamine was not observed. Methane and ammonia were produced from the three methylamines by M. barkeri in amounts expected on the basis of the appropriate fermentation equations. The growth yield was 5.8 mg of cells (dry weight) per mmol of methane and was not dependent on the kind of methyl compound used as substrate.

Euryarchaeota↗

PubMed1977

Lack of peptidoglycan in the cell walls of Methanosarcina barkeri.

Neither muramic acid and glucosamine nor D-glutamic acid or other amino acids typical of peptidoglycan were found in cell walls of two strains of Methanosarcina barkeri. The main components are galactosamine, neutral sugars and uronic acids. Therefore, the structural component of the cell wall most likely consists of an acid heteropolysaccharide, resembling that of Halococcus morrhuae. It is, however, not sulfated.

Bacteria↗

PubMed1977

Citrate, a specific substrate for the isolation of Clostridium sphenoides.

With a medium containing citrate as the carbon and energy source, 10 clostridial strains were isolated from various mud samples. Characterization of these strains revealed that they all belonged to the same species, Clostridium sphenoides. Strains of this organism obtained from culture collections were also able to grow citrate, whereas 15 other clostridial species tested were not. Citrate was fermented by C. sphenoides to acetate, ethanol, carbon dioxide, and hydrogen. Experiments with stereospecifically 14C-labeled citrate indicated that citrate lyase was involved in citrate degradation.

Acetates↗

PubMedDate not supplied

Purification and substrate specificity of two cysteine proteinases of Giardia lamblia.

The proteinase activity present in homogenates of trophozoites of Giardia lamblia, active on azocasein and urea-denaturated hemoglobin, was separated into two different enzymes by a series of purification procedures. These procedures included gel filtration on Fractogel TSK HW-55 (F), organomercurial agarose affinity chromatography, and ion exchange chromatography on DEAE-cellulose. By chromatography on Sephadex G-100, two purified enzymes exhibited relative molecular weights of Mr = 95,000 and 35,000 +/- 10%, respectively. On the basis of inhibition by thiol reagents and abrogation of this effect by dithiothreitol and cysteine, they were identified as cysteine proteinases. Proteinase I (Mr = 95,000) and proteinase II (Mr = 35,000) were active against the beta-chain of insulin releasing characteristic fragments. However, differences in substrate specificities of the two enzymes could be observed by using synthetic peptides that represent sequences 1-6, 8-18, and 20-30 of the insulin beta-chain. Furthermore, the synthetic tetrapeptides Arg-Gly-Phe-Phe, Arg-Gly-Leu-Hyp, and Arg-Arg-Phe-Phe were hydrolyzed by the two proteinases releasing Phe-Phe and Leu-Hyp, respectively. Compared with Arg-Gly-Phe-Phe, the rates of hydrolysis of Arg-Gly-Leu-Hyp and Arg-Arg-Phe-Phe at substrate concentrations of 1 mM were 91% and 63% (proteinase I) and 80% and 57% (proteinase II), respectively.

Amino Acid Sequence↗