Enzymatic evidence for involvement of the methylmalonyl-CoA pathway in propionate oxidation by Syntrophobacter wolinii

Enzyme measurements were carried out with crude cell-free extracts of the propionate oxidizing coculture of Syntrophobacter wolinii and Desulfovibrio G11. Using cell-free extracts of a pure culture of Desulfovibrio G11 as a blank, most of the enzymes involved in the methylmalonyl-CoA pathway for propionate oxidation, including a propionyl-CoA: oxaloacetate transcarboxylase, were demonstrated in S. wolinii.     

Identification of crossovers in Wilson disease families as reference points for a genetic localization of the gene

Summary Wilson disease (WD) is an autosomal recessive disorder of copper metabolism. A minimum recombinant analysis using D13S22, ESD, RB1, D13S31, D13S55, D13S26, D13S39, and D13S12, all localized at 13q14-q22, has been carried out in 20WD families of Northwest-European origin. No inconsistencies have been observed with respect to locus order or location of the WD locus (WND) compared with previous linkage studies. D13S31 was mapped as the closest marker proximal to WND, whereas D13S55 and D13S26 were mapped as the closest markers distal to WND. We have identified a crossover between WND and D13S31 in one family and a crossover between WND and D13S55 in another. These crossover sites can be used as reference points for new chromosome 13q14-q21 markers, and are therefore important for a more accurate mapping of the WD locus.     

Thermophilic,anaerobic degradation of gelatin by Thermobacteroides proteolyticus

Summary The anaerobic thermophilic proteolysis of gelatin by Thermobacteroides proteolyticus (strain BT = ATCC 35245) was investigated. Gelatin was fermented within 5 to 7 days to mainly acetic acid, isobutyric acid, isovaleric acid, and ammonium. Carbon dioxide and hydrogen were produced as well. Maximal ammonification of organic-N was observed at an initial gelatin concentration greater than 2.7 and lower than 10 g/l. Gelatin degradation was not influenced when various amounts of yeast extract (0 to 1 g/l) or ammonium chloride (0 to 6 g/l) were added to the medium.     

Activation and inactivation of methanol: 2-mercaptoethanesulfonic acid methyltransferase from Methanosarcina barkeri.

Methanol is converted to methane by crude extracts of Methanosarcina barkeri. The first reaction involved in this process, is catalyzed by methanol:2-mercaptoethanesulfonic acid methyltransferase (EC 2.1.1.-). The methyltransferase has an optimum at pH 6.5 and is not inhibited by 2-bromoethanesulfonic acid. Pyridoxal-5'-phosphate acts as an inhibitor (Ki = 0.30 mM). The methyltransferase was tested in the presence of 2-bromoethanesulfonic acid, which inhibits the conversion of 2-(methylthio)ethanesulfonic acid to methane. The reaction is subject to activation and inactivation. Inactivation is brought about by the presence of oxygen, flavin mononucleotide, flavin adenine dinucleotide, and 2-(methylthio)ethanesulfonic acid, the product of the reaction. Activation of the system requires the presence of ATP and Mg2+ and of hydrogen. Hydrogen can be replaced by enzymatic systems, such as pyruvate dehydrogenase, which deliver free hydrogen.     

Catch-up growth and endocrine changes in childhood celiac disease. Endocrine changes during catch-up growth

Childhood celiac disease may lead to a failure of statural growth. After institution of a gluten-free diet most patients exhibit catch-up growth. Catch-up growth is a remarkable phenomenon characterized by a supranormal height velocity. One of the hypothetical mechanisms of catch-up growth is that an increased activity of the somatotrophic axis is involved. In order to provide further insight in the physiology of catch-up growth, auxological and endocrine changes were prospectively studied in 28 children with newly diagnosed celiac disease. The results demonstrate a malnutrition-like state of the somatotrophic axis at the time of diagnosis and a rapid recovery of this axis towards normal functioning after institution of the gluten-free diet. Although several correlations between these endocrine alterations and auxological parameters were detected, it is questionable whether the endocrine changes are the driving force behind catch-up growth.     

Interactions among oscillatory pathways in NF-kappa B signaling

Background  

Sustained stimulation with tumour necrosis factor alpha (TNF-alpha) induces substantial oscillations—observed at both the single cell and population levels—in the nuclear factor kappa B (NF-kappa B) system. Although the mechanism has not yet been elucidated fully, a core system has been identified consisting of a negative feedback loop involving NF-kappa B (RelA:p50 hetero-dimer) and its inhibitor I-kappa B-alpha. Many authors have suggested that this core oscillator should couple to other oscillatory pathways.     

Adsorption of ethylenediaminetetraacetic dianhydride modified oxalate decarboxylase on calcium oxalate

We used ethylenediaminetetraacetic acid dianhydride (EDTAD) to modify oxalate decarboxylase (OXDC) to improve its adsorption on calcium oxalate stones. The modified sites were identified by Ultra performance liquid chromatography-mass spectrometry (UPLC-MS) and the adsorption mechanism of the EDTAD-modified OXDC on calcium oxalate (CaOx) was investigated. We investigated adsorption time, initial enzyme concentration, temperature and solution pH on the adsorption process. Data were analyzed using kinetics, thermodynamics and isotherm adsorption models. UPLC-MS showed that EDTAD was attached to OXDC covalently and suggested that the chemical modification occurred at both the free amino of the side chain and the α-NH₂ of the peptide. The adsorption capacity of the EDTAD-OXDC on calcium oxalate was 53.37% greater than that of OXDC at the initial enzyme concentration of 5 mg/ml, pH = 7.0, at 37° C. The modified enzyme (EDTAD-OXDC) demonstrated improved oxalate degradation activity at pH 4.5?6.0. Kinetic data fitting analysis suggested a pseudo second order kinetic model. Estimates of the thermodynamic parameters including ΔG⁰, ΔH⁰ and ΔS⁰ of the adsorption process showed it to be feasible, spontaneous and endothermic. Isotherm data fitting analysis indicated that the adsorption process is reduced to monolayer adsorption at a low enzyme concentration and to multilayer adsorption at a high enzyme concentration. It may be possible to apply OXDC to degradation of calcium oxalate stones.