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PubMed1986

Biochemical Aspects of Fumaric Acid Accumulation by Rhizopus arrhizus.

The accumulation and excretion of fumaric acid, and to a lesser extent malic and succinic acids, by Rhizopus arrhizus occurs under aerobic conditions in a high-glucose medium containing a limiting amount of nitrogen and a neutralizing agent (CaCO(3)). An overall four-carbon dicarboxylic acid molar yield of up to 145% (moles of acid produced per mole of glucose utilized) is obtained after incubation for 4 to 5 days. Evidence is presented that fumarate is synthesized from pyruvate via a carboxylation reaction yielding oxaloacetate, which is then converted to malate and further on to fumarate via the reductive reactions of the tricarboxylic acid cycle. The possible formation of fumarate from the normal (oxidative) operation of the tricarboxylic acid cycle was not excluded by the data. Yield, C nuclear magnetic resonance, and enzymatic activity studies were carried out in a strain of R. arrhizus which produces high levels of fumarate from glucose and carbonate. The observed high fumarate molar yield (greater than 100%) can therefore be explained in terms of the carboxylation of pyruvate and the operation of the reductive reactions of the tricarboxylic acid cycle under aerobic conditions.

Journal Article↗
PubMed1977

Yersinia enterocolitica: biochemical, serological, and gas-liquid chromatographic characterization of rhamnose-, raffinose-, melibiose-, and citrate-utilizing strains.

Thirteen atypical Yersinia enterocolitica isolates, all fermenting rhamnose, raffinose, and melibiose and utilizing sodium citrate within 24 to 48 h at 22 degrees C (Y.e.rh+), were examined biochemically-serologically, and by gas-liquid chromatography. These data, as well as cultural, biochemical, and antibiotic susceptibility data gathered from two previous studies involving (i) these same atypical Y.e.rh+ isolates, (ii) Y. enterocolitica serotypes O:1 through O:15 (rhamnose, raffinose, and citrate negative [Y.e.rh-]), (iii) Y. enterocolitica serotype O:16 (rhamnose positive but raffinose and citrate negative), and (iv) Yersinia pseudotuberculosis serogroups I through V were statistically compared. Both preand postabsorption agglutination studies demonstrated the serological distinctiveness of Y.e.rh+ from Y.e.rh- and Y. pseudotuberculosis. At the same time, three immunological groups among the 13 Y.e.rh+ strains were seen; 8 corresponded to Y. enterocolitica serotype O:17; 1 to Y. enterocolitica serotype O:16; and the remaining four were nontypable in antisera against known Y. enterocolitica antigen types. Each of the three Yersinia groups tested chromatographically produced acetic and lactic acids. Both Y.e.rh- and Y.e.rh+ formed propionic acid, but only Y.e.rh+ produced detectable amounts of succinic acid. Based on 49 variables, statistical analysis of the three Yersinia groups studied placed each of the Y.e.rh+ strains in a homogeneous group separate from both Y.e.rh- and Y. pseudotuberculosis. These data, coupled with deoxyribonucleic acid homology studies of Brenner and co-workers (D. J. Brenner, A. G. Steigerwalt, D. F. Falcao, R. E. Weaver, and G. R. Fanning, Int. J. Syst. Bacteriol. 26:180-194, 1976), support the distinctiveness of Y.e.rh+ from typical Y. enterocolitica and Y. pseudotuberculosis.

Chromatography, Gas↗
PubMed1993

Inherited disorders of GABA metabolism.

Gamma-aminobutyric acid (GABA), a major inhibitory neurotransmitter in the mammalian central nervous system, is produced from glutamic acid in a reaction catalysed by glutamic acid decarboxylase. The sequential actions of GABA-transaminase (converting GABA to succinic semialdehyde) and succinic semialdehyde dehydrogenase (oxidizing succinic semialdehyde to succinic acid) allow oxidative metabolism of GABA through the tricarboxylic acid cycle. The inherited disorders of GABA metabolism include: (1) pyridoxine-dependent seizures (?glutamic acid decarboxylase deficiency) (> 50 patients); (2) GABA-transaminase deficiency (2 patients/1 family); (3) succinic semialdehyde dehydrogenase deficiency (32 patients/21 families); and (4) homocarnosinosis associated with serum carnosinase deficiency (3 patients/1 family). Homocarnosine is a brain-specific dipeptide of GABA and L-histidine. Of these four defects, definitive enzymatic diagnoses have been made only for GABA-transaminase and succinic semialdehyde dehydrogenase deficiencies. The presumptive mode of inheritance for all disorders is autosomal recessive, and all are associated with central nervous system dysfunction. Only succinic semialdehyde dehydrogenase deficiency manifests organic aciduria, which may account for the higher number of patients identified with this disorder; identification of additional patients with some of the other disorders will require increased request for analysis of cerebrospinal fluid metabolites by paediatricians and neurometabolic specialists.

4-Aminobutyrate Transaminase↗
PubMedDate not supplied

[Activity of Krebs cycle oxidative enzymes in the brain in hypothermia].

Cooling of rats down to the rectal temperature of 33--35 degrees without the use of narcotic and neuroplegic drugs did not cause distinct alterations in activity of the oxidative enzymes of tricarboxylic acid cycle--isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, malate-, succinate- and pyruvate dehydrogenases in brain tissue. At the same time, inhibition of the activity of these dehydrogenases occurred in profound hypothermia (cooling to 19--20 degrees). In this case the activity of succinate dehydrogenase was decreased less distinctly as compared with the activity of NAD-dependent dehydrogenases. Succinic acid appears to be an especially important substrate for oxidation in brain of the chilled rats.

Animals↗
PubMed1993

Inhibition of human oral squamous carcinoma cell (SCC-25) proliferation by prostaglandin E2 and vitamin E succinate.

The primary objective of this investigation was to study the effect of D-alpha-tocopherol acid succinate (vitamin E succinate) and prostaglandin E2 (PGE2), individually and in combination, on the proliferation of human tongue squamous carcinoma cells (SCC-25) in vitro. Test compounds in varying concentrations were incubated with cells in serum-free Dulbecco's Modified Eagle's Medium-Ham's F-12 Medium (50:50), supplemented with 0.1% albumin for sixteen hours. Cell proliferation was measured by the incorporation of [3H] thymidine in acid-insoluble material (i.e. DNA). Prostaglandin E2 and vitamin E succinate, individually at 10(-9)-10(-6) M, caused significant dose-dependent inhibition in DNA synthesis. A combined dose of each compound at 10(-5) M resulted in significant additive inhibition which averaged 43.53% (p < 0.005). Addition of indomethacin (INDO) to cell cultures induced significant dose-dependent stimulation in DNA synthesis. Hence, we might suggest that the overall potential of vitamin E in controlling malignant cell proliferation in vivo could be due to its own effect combined with that of endogenous PGs which are normally produced in excessive amounts by malignant cells.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

B-Domain deleted recombinant coagulation factor VIII modified with monomethoxy polyethylene glycol.

Recombinant coagulation factor VIII (r-VIII SQ) was chemically modified with monomethoxy poly(ethylene glycol) (mPEG). Three mPEG derivatives were used for coupling to the r-VIII SQ lysines, a mixed anhydride of monomethoxy poly(ethylene glycol) succinic acid (mPEG-SAH), monomethoxy poly(ethylene glycol) succinimidyl succinate (mPEG-SS), and monomethoxy poly(ethylene glycol) tresylate (mPEG-TRES). A consequence of the modification with all derivatives was a substantial reduction in coagulant activity, even at very low degrees of modification. A method was developed with the purpose of avoiding conjugation at certain important biological sites on the factor VIII and thereby producing conjugates with better retained activity. This was achieved by immobilizing the protein onto a solid matrix during the modification reaction. Characterization of conjugates by SDS-PAGE, western blots, interaction with von Willebrand factor (vWf), and thrombin activation/inactivation analyses was undertaken. The SDS-PAGE and western blots revealed coupling heterogeneity regarding degree of modification. The amount of factor VIII able to bind to vWf decreased with the conjugation. Thrombin activated the modified factor VIII to essentially the same extent as the reference preparation of r-VIII SQ. Inactivation of the modified factor VIII was, however, slower than inactivation of the unmodified protein. Finally, an in vitro study was performed to evaluate the influence of the mPEG modification on the protein stability in extract of porcine tissue. Despite that conjugates with low degrees of modification were included in the study, the coagulant activity was preserved to a significantly higher extent in all incubation mixtures containing conjugates compared to that with unmodified protein.

Animals↗
PubMed2003

Effect of alkyl group size on the mechanism of acid hydrolyses of benzaldehyde acetals.

Hydrolyses of benzaldehyde acetals, PhCH(OR)(2), are specific hydrogen-ion catalyzed when R = methyl, n-butyl, but with secondary and tertiary alkyl derivatives, R = i-propyl, s-butyl, t-butyl, t-amyl, hydrolyses are general-acid catalyzed. The Brønsted alpha values for both secondary and tertiary alkyl groups are in the range: alpha = 0.57-0.61. A simple iterative procedure was developed to estimate the individual rate constants for general-acid catalysis by the diacid and monoacid forms of succinic acid buffer. Plots of log k(obs) (at [buffer] = 0 M) against pH are linear for the secondary and tertiary acetals, and plots of log k(H) for the H(3)O(+)-catalyzed reaction, (13)C and (1)H chemical shifts, and (1)J(CH) coupling constants against the Charton steric parameter, nu, for alkoxy groups are linear. The second-order rate constant, k(H), increases about 100-fold on going from R = Me to R = t-amyl, indicating the significant role of steric effects on reactivity. Steric effects upon (13)C NMR chemical shifts and coupling constants indicate that increasing the bulk of the alkoxy moiety increases the electron density at the carbon reaction center, which accelerates hydrolysis. Analysis of the Jencks-More-O'Ferrall free energy diagram for the reaction provides support for concerted proton transfer and C-O bond breaking in the transition state for hydrolyses of benzaldehyde acetals with secondary and tertiary alkyl groups in contrast to specific hydrogen catalysis with R = Me and n-Bu. All our results are consistent with rate-determining acid hydrolysis of benzaldehyde dialkyl acetals to hemiacetal intermediates that breakdown rapidly to benzaldehyde.

Journal Article↗
PubMed1987

Susceptibility and resistance of ruminal bacteria to antimicrobial feed additives.

Susceptibility and resistance of ruminal bacterial species to avoparcin, narasin, salinomycin, thiopeptin, tylosin, virginiamycin, and two new ionophore antibiotics, RO22-6924/004 and RO21-6447/009, were determined. Generally, antimicrobial compounds were inhibitory to gram-positive bacteria and those bacteria that have gram-positive-like cell wall structure. MICs ranged from 0.09 to 24.0 micrograms/ml. Gram-negative bacteria were resistant at the highest concentration tested (48.0 micrograms/ml). On the basis of their fermentation products, ruminal bacteria that produce lactic acid, butyric acid, formic acid, or hydrogen were susceptible and bacteria that produce succinic acid or ferment lactic acid were resistant to the antimicrobial compounds. Selenomonas ruminantium was the only major lactic acid-producing bacteria resistant to all the antimicrobial compounds tested. Avoparcin and tylosin appeared to be less inhibitory (MIC greater than 6.0 micrograms/ml) than the other compounds to the two major lactic acid-producing bacteria, Streptococcus bovis and Lactobacillus sp. Ionophore compounds seemed to be more inhibitory (MIC, 0.09 to 1.50 micrograms/ml) than nonionophore compounds (MIC, 0.75 to 12.0 micrograms/ml) to the major butyric acid-producing bacteria. Treponema bryantii, an anaerobic rumen spirochete, was less sensitive to virginiamycin than to the other antimicrobial compounds. Ionophore compounds were generally bacteriostatic, and nonionophore compounds were bactericidal. The specific growth rate of Bacteroides ruminicola was reduced by all the antimicrobial compounds except avoparcin. The antibacterial spectra of the feed additives were remarkably similar, and it appears that MICs may not be good indicators of the potency of the compounds in altering ruminal fermentation characteristics.

Animal Feed↗
PubMed1996

Enhanced Glycerol Content in Wines Made with Immobilized Candida stellata Cells.

Screening tests carried out for 10 strains of Candida stellata confirmed high levels of glycerol production, although a low fermentation rate and reduced ethanol content were observed. To overcome the poor competition with Saccharomyces cerevisiae, fermentation tests with immobilized C. stellata cells, alone or in combination with S. cerevisiae, have been carried out. The immobilization of C. stellata cells consistently reduced the fermentation length when compared with that obtained with free cells, immobilized cells exhibiting about a 30-and a 2-fold improvement in fermentation rate compared with rates for C. stellata and S. cerevisiae free cells, respectively. Moreover, immobilized C. stellata cells produced a twofold increase in ethanol content and a strong reduction in acetaldehyde and acetoin production in comparison with levels for free cells. The evaluation of different combinations of C. stellata immobilized cells and S. cerevisiae showed interesting results with regard to analytical profiles for practical application in wine making. In fact, analytical profiles of combinations showed, apart from a high glycerol content, a reduction in the amounts of acetic acid and higher alcohols and a consistent increase in succinic acid content in comparison with values for the S. cerevisiae control strain. Sequential fermentation first with immobilized C. stellata cells and then after 3 days with an added inoculum of S. cerevisiae free cells was the best combination, producing 15.10 g of glycerol per liter, i.e., 136% more than the S. cerevisiae control strain produced. Fermentation with immobilized C. stellata cells could be an interesting process by which to enhance glycerol content in wine.

Journal Article↗
PubMed1982

A cyclohexanecarboxylic acid utilizing yeast: isolation, identification, and nutritional characteristics.

A yeast capable of utilizing cyclohexanecarboxylic acid as sole carbon and energy source, strain KUY-6A, was isolated from soil by enrichment cultures. Taxonomical studies indicated that strain KUY-6A was Trichosporon cutaneum. Strain KUY-6A grew on a number of carboxylic acids. Among the cyclic compounds tested, cyclohexanecarboxylic acid was the best substrate. Cyclopentanecarboxylic acid, cycloheptanecarboxylic acid, cyclopentanone, cyclohexanone, and cyclopentanol also supported growth. In addition, the organism used the monocarboxylic acids, butyric, valeric, and caproic; the dicarboxylic acids succinic, glutaric, adipic, pimelic, and suberic; and the aromatic acids, benzoic and o-, m-, and p-hydroxybenzoic. The yeast did not require any vitamins for growth, although thiamine gave slight stimulation. The cell dry weight yield was 0.75 g from 1 g cyclohexanecarboxylic acid used.

Cyclohexanecarboxylic Acids↗
PubMed2003

[HIV-inhibiting activity of polyanion matrices and related substances containing adamantane and norbornene pharmacophores].

Analysis of molecular mechanisms of HIV-infection and targets for therapeutic intervention allowed to offer strategy for design of new effective anti-HIV/AIDS agents on the basis of two key principles: 1) intervention to infectious process beginning from the earliest stages of the virus penetration into cells; 2) blockade of not only one but several molecular targets of the HIV life cycle. The paper presents the results of the in vitro investigation of the anti-HIV activity (against several HIV-1 strains, including AZT-resistant ones) of new generation complex substances synthesized with application of the molecular substrategy for bifunctional inhibitors on the basis of a combination of nonspecific antiviral active polymeric anions with selective virus sensitive membranotropic pharmacophores of the adamantane and norbornene lines. The HIV-1 inhibiting potential of polymeric carboxylic acids (PKA) of various nature: synthetic polymeric analogues of succinic acid and carboxymethylated dextran was evaluated. It was shown that the antiviral action of PKA is located at the initial stages of HIV-1 penetration into cells and is markedly defined by balance of electrostatic activity and conformational mobility of the macromolecules. This corresponds to the evidence of the negatively charged macromolecules ability to bind the positively charged V3 loop within the viral protein gp120, preventing the HIV-1 adsorption on the surface of permissive cells. Chemical conjugation of the PKA with derivatives of the adamantane (amantadine and rimantadine analogues) or norbornene (related to deitiforin and natural bicyclic therpenoids) via spacer groups provides synergistic elevation of the anti-HIV-1 activity, first of all for the flexible chain PKA. The obtained result experimentally confirmed the theoretically predicted expansion of the anti-HIV-1 action of the bifunctional kind antivirals due to cooperation of the electrostatic potential of PKA with the virus specific hydrophobic activity needed to block postadsorption events of the HIV-1 life cycle, including both the virus penetration into cells and the virus posterity release from the infected cells. Additional cooperation of PKA with some special vectors targeted towards "Raft" domains of cellular membranes, epicentres for natural location of initial and completed stages of the HIV-1 replication cycle was also shown promising. The structure-function optimized samples exhibit high indexes of anti-HIV-1 selectivity up to IS50 = 10000.

Adamantane↗
PubMed2002

Differences between mouse and rat pancreatic islets: succinate responsiveness, malic enzyme, and anaplerosis.

Succinic acid methyl esters are potent insulin secretagogues in rat pancreatic islets, but they do not stimulate insulin release in mouse islets. Unlike rat and human islets, mouse islets lack malic enzyme and, therefore, are unable to form pyruvate from succinate-derived malate for net synthesis of acetyl-CoA. Dimethyl-[2,3-(14)C]succinate is metabolized in the citric acid cycle in mouse islets to the same extent as in rat islets, indicating that endogenous acetyl-CoA condenses with oxaloacetate derived from succinate. However, without malic enzyme, the net synthesis from succinate of the citric acid cycle intermediates citrate, isocitrate, and alpha-ketoglutarate cannot occur. Glucose and other nutrients that augment alpha-ketoglutarate formation are secretagogues in mouse islets with potencies similar to those in rat islets. All cycle intermediates can be net-synthesized from alpha-ketoglutarate. Rotenone, an inhibitor of site I of the electron transport chain, inhibits methyl succinate-induced insulin release in rat islets even though succinate oxidation forms ATP at sites II and III of the respiratory chain. Thus generating ATP, NADH, and anaplerosis of succinyl-CoA plus the four-carbon dicarboxylic acids of the cycle and its metabolism in the citric acid cycle is insufficient for a fuel to be insulinotropic; it must additionally promote anaplerosis of alpha-ketoglutarate or two intermediates interconvertible with alpha-ketoglutarate, citrate, and isocitrate.

Animals↗
PubMed1984

A multinuclear NMR relaxation study of the interaction of divalent metal ions with L-aspartic acid.

Carbon-13 spin-lattice relaxation times, T1, have been measured for aqueous solutions of L-aspartic acid, L-alanine, O-phospho-L-serine, and 2-mercapto-L-succinic acid in the presence of the paramagnetic metal ions, Cu2+ and Mn2+, and Mg2+ as a diamagnetic control, at ambient temperature and neutral pH. Nitrogen-15, oxygen-17 and proton relaxation times were also obtained for L-aspartic acid and phosphorus-31 relaxation times for O-phospho-L-serine under similar conditions. The structures of these complexes in solution were determined from the various metal ion-nuclei distances calculated from the paramagnetically-induced relaxation. These results indicate that the Cu2+ interaction with L-aspartic acid is through alpha-amino and beta-carboxyl groups while Mn2+ coordinates most strongly through alpha- and beta-carboxyl groups, with the possibility of a weak interaction through the amino group. An examination of the coordination of these divalent metal ions to an analog of L-aspartic acid in which the beta-carboxyl group is replaced by a phosphate group (O-phospho-L-serine) indicated that Cu2+ coordination is now probably through the alpha-amino and phosphate groups, while this analog is a monodentate ligand for Mn2+ coordinating through the phosphate group. Removal of the beta-carboxyl group (L-alanine) also results in Cu2+ coordination through the alpha-carboxyl and alpha-amino groups, and the same ligand interactions are observed with Mn2+. Replacement of the alpha-amino group of L-aspartic acid with an -SH group (2-mercapto-L-succinate) is sufficient to eliminate any specific coordination with either Cu2+ or Mn2+.

Alanine↗
PubMed1984

The chemical conditions on the parent body of the Murchison meteorite: some conclusions based on amino, hydroxy and dicarboxylic acids.

Amino and hydroxy acids have been identified in the Murchison meteorite. Their presence is consistent with a synthetic pathway involving aldehydes, hydrogen cyanide and ammonia in an aqueous environment (Strecker-cyanohydrin synthesis). From the various equilibrium and rate constants involved in this synthesis, four independent estimates of the ammonium ion concentrations on the parent body at the time of compound synthesis are obtained; all values are about 2 x 10(-3) M. Succinic acid and beta-alanine have also been detected in the Murchison meteorite. Their presence is consistent with a synthesis from acrylonitrile, hydrogen cyanide and ammonia. Using the equilibrium and rate constants for this synthetic pathway, and the succinic acid/beta-alanine ratio measured in the Murchison meteorite, an estimate of the hydrogen cyanide concentration of 10(-3) to 10(-2) M is obtained. Since hydrogen cyanide hydrolyzes relatively rapidly in an aqueous environment (t1/2 < 10(4) yrs) this high concentration implies a period of synthesis of organic compounds as short as 10(4) years on the Murchison meteorite parent body.

Acrylonitrile↗
PubMed2006

Thermodynamic models of aqueous solutions containing inorganic electrolytes and dicarboxylic acids at 298.15 K. 2. Systems including dissociation equilibria.

Atmospheric aerosols contain a significant fraction of water-soluble organic compounds, including dicarboxylic acids. Pitzer activity coefficient models are developed, using a wide range of data at 298.15 K, for the following systems containing succinic acid (H(2)Succ) and/or succinate salts: [H(+), Li(+), Na(+), K(+), Rb(+), Cs(+)]Cl(-)-H(2)Succ-H(2)O, HNO(3)-H(2)Succ-H(2)O, H(+)-NH(4)(+)-HSucc(-)-Succ(2-)-NH(3)-H(2)Succ-H(2)O, NH(4)Cl-(NH(4))(2)Succ-H(2)O, H(+)-Na(+)-HSucc(-)-Succ(2-)-Cl(-)-H(2)Succ-H(2)O, NH(4)NO(3)-H(2)Succ-H(2)O, and H(2)SO(4)-H(2)Succ-H(2)O. The above compositions are given in terms of ions in the cases where acid dissociation was considered. Pitzer models were also developed for the following systems containing malonic acid (H(2)Malo): H(+)-Na(+)-HMalo(-)-Malo(2-)-Cl(-)-H(2)Malo-H(2)O, and H(2)Malo-H(2)SO(4)-H(2)O. The models are used to evaluate the extended Zdanovskii-Stokes-Robinson (ZSR) model proposed by Clegg and Seinfeld (J. Phys. Chem. A 2004, 108, 1008-1017) for calculating water and solute activities in solutions in which dissociation equilibria occur. The ZSR model yields satisfactory results only for systems that contain moderate to high concentrations of (nondissociating) supporting electrolyte. A practical modeling scheme is proposed for aqueous atmospheric aerosols containing both electrolytes and dissociating (organic) nonelectrolytes.

Dicarboxylic Acids↗