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PubMedDate not supplied

[The determination of chromium in cadaveric material by using cyclohexanecarboxylic acid].

Method of chrome detection in the course of forensic chemical investigation in the cadaveric material on the basis of cyclohexan-carbonic acid use is presented. Results of experimental researches showed efficacy of method tested as compared to the common one. Method suggested can be used in laboratory conditions to extract chrome from visceral organs of human cadaver.

Cadaver↗
PubMed1997

Binding of cyclodextrins to alicyclic and aromatic substrates: complex formation of alpha-, beta-, and gamma-cyclodextrins with substituted cyclohexanecarboxylic acids and phenylalkanoic acids.

Complex binding constants of the three native cyclodextrins with seven cyclohexane derivatives (all possessing the carboxylic acid group) and with the series C6H5(CH2)nCOOH (n = 0 to 4) were measured in aqueous solution at 25 degrees C by potentiometry and the solubility method. These results, combined with literature data, indicate that alpha- and gamma-cyclodextrins bind with comparable strength to both the cyclohexyl and phenyl moieties, with beta-cyclodextrin binding significantly more strongly. These acid series are compared with several series CH3(CH2)nX, where X is CH3, COOH, COO-, OH, SO3-, etc., and it is concluded that the X group (for X other than methyl) contributes appreciably to complex stability, perhaps by means of an extracavity interaction. The COOH group provides a further augmentation of complex stability. NMR CIS and ROESY results indicate the presence of isomeric complexes in both the cyclohexyl and phenylalkanoic series, and clearly demonstrate the existence of intracavity inclusion. An NOE study of the alpha-cyclodextrin: cyclohexanecarboxylate system provides evidence for inclusion combined with interaction outside (that is, at the rim of) the cavity.

Binding Sites↗
PubMed2000

Two diastereomers of (+-)-cis-2-(3-oxo-1,3,4,5,6, 7-hexahydroisobenzofuran-1-yl)cyclohexanecarboxylic acid

The structures are presented for both diastereomers of the title compound, C(15)H(20)O(4), produced by base-catalyzed self-condensation of cyclohexane-cis-1,2-dicarboxylic anhydride in refluxing triethylamine. Equilibration of either diastereomer under the condensation conditions yielded the same 5:3 mixture. In the crystal, one diastereomer, (II), is ordered, while the other, (I), displays both flexional ring disorder and carboxyl disorder; both aggregate as centrosymmetric hydrogen-bonded dimers [for (I), O.O = 2.680 (2) A; for (II), O.O = 2.635 (4) A].

Journal Article↗
PubMed2000

Anaerobic naphthalene degradation by a sulfate-reducing enrichment culture.

Anaerobic naphthalene degradation by a sulfate-reducing enrichment culture was studied by substrate utilization tests and identification of metabolites by gas chromatography-mass spectrometry. In substrate utilization tests, the culture was able to oxidize naphthalene, 2-methylnaphthalene, 1- and 2-naphthoic acids, phenylacetic acid, benzoic acid, cyclohexanecarboxylic acid, and cyclohex-1-ene-carboxylic acid with sulfate as the electron acceptor. Neither hydroxylated 1- or 2-naphthoic acid derivatives and 1- or 2-naphthol nor the monoaromatic compounds ortho-phthalic acid, 2-carboxy-1-phenylacetic acid, and salicylic acid were utilized by the culture within 100 days. 2-Naphthoic acid accumulated in all naphthalene-grown cultures. Reduced 2-naphthoic acid derivatives could be identified by comparison of mass spectra and coelution with commercial reference compounds such as 1,2,3, 4-tetrahydro-2-naphthoic acid and chemically synthesized decahydro-2-naphthoic acid. 5,6,7,8-Tetrahydro-2-naphthoic acid and octahydro-2-naphthoic acid were tentatively identified by their mass spectra. The metabolites identified suggest a stepwise reduction of the aromatic ring system before ring cleavage. In degradation experiments with [1-(13)C]naphthalene or deuterated D(8)-naphthalene, all metabolites mentioned derived from the introduced labeled naphthalene. When a [(13)C]bicarbonate-buffered growth medium was used in conjunction with unlabeled naphthalene, (13)C incorporation into the carboxylic group of 2-naphthoic acid was shown, indicating that activation of naphthalene by carboxylation was the initial degradation step. No ring fission products were identified.

Anaerobiosis↗
PubMed2000

A novel delta(3),delta(2)-enoyl-CoA isomerase involved in the biosynthesis of the cyclohexanecarboxylic acid-derived moiety of the polyketide ansatrienin A.

The side chain of the antifungal polyketide ansatrienin A produced by Streptomyces collinus contains a cyclohexanecarboxylic acid (CHC) derived moiety. This CHC in the coenzyme A activated form (CHC-CoA) is derived from shikimic acid via a pathway in which the penultimate step is the isomerization of 2-cyclohexenylcarbonyl-CoA to 1-cyclohexenylcarbonyl-CoA. We have purified a 28 kDa 2-cyclohexenylcarbonyl-CoA isomerase (ChcB) from S. collinus and cloned and sequenced the corresponding chcB gene. The predicted amino acid sequence of ChcB showed moderate sequence identity to members of the hydratase/isomerase superfamily of enzymes. The recombinant ChcB was overexpressed in Escherichia coli and purified to homogeneity using metal chelate chromatography. Kinetic analysis demonstrated that recombinant ChcB had wide substrate specificity and could catalyze a double bond isomerization using 2-cyclohexenylcarbonyl-CoA (K(m) 116 +/- 68 microM, k(cat)( )()3.7 +/- 1.0 min(-)(1)), trans-3-hexenyl-CoA (K(m) 39 +/- 10 microM, k(cat)( )()12.8 +/- 1 min(-)(1)), and vinylacetyl-CoA (K(m) 156 +/- 34 microM, k(cat)( )()29 +/- 3 min(-)(1)) as substrates. ChcB activity in cell extracts of S. collinus SP1, an insertionally disrupted chcB mutant, was shown to decrease by more than 99% (as compared to the wild-type strain) using all three of these substrates. The S. collinus SP1 strain, unlike the wild-type strain, could not produce omega-cyclohexyl fatty acids but was still able to grow efficiently on methyl oleate as a sole carbon source. These observations demonstrate that the S. collinus ChcB is required for catalyzing the isomerization of 2-cyclohexenylcarbonyl-CoA to 1-cyclohexenylcarbonyl-CoA during CHC-CoA biosynthesis but not for degradation of unsaturated fatty acids. The chcB gene does not appear to be associated with the ansatrienin biosynthetic gene cluster, which has previously been shown to contain at least one gene known to be essential for CHC-CoA biosynthesis. This finding represents a notable exception to the general rule regarding the clustering of polyketide biosynthetic pathway genes.

Amino Acid Sequence↗
PubMed2006

Genetic manipulation of the biosynthetic process leading to phoslactomycins, potent protein phosphatase 2A inhibitors.

Phoslactomycins (PLMs) represent an unusual structural class of natural products secreted by various streptomycetes, containing an alpha,beta-unsaturated delta-lactone, an amino group, phosphate ester, conjugated diene and a cyclohexane ring. Phosphazomycins, phospholines and leustroducsins contain the same structural moieties, varying only in the acyl substituent at the C-18 hydroxyl position. These compounds possess either antifungal or antitumor activities or both. The antitumor activity of the PLM class of compounds has been attributed to a potent and selective inhibition of protein phosphatase 2A (PP2A). The cysteine-269 residue of PP2Ac-subunit has been shown to be the site of covalent modification by PLMs. In this article, we review previous work on the isolation, structure elucidation and biological activities of PLMs and related compounds and current status of our work on both PLM stability and genetic manipulation of the biosynthetic process. Our work has shown that PLM B is surprisingly stable in solution, with a pH optimum of 6. Preliminary biosynthetic studies utilizing isotopically labeled shikimic acid and cyclohexanecarboxylic acid (CHC) suggested PLM B to be a polyketide-type antibiotic synthesized using CHC as a starter unit. Using a gene (chcA) from a set of CHC-CoA biosynthesis genes from Streptomyces collinus as a probe, a 75 kb region of 29 ORFs encoding PLM biosynthesis was located in the genome of Streptomyces sp. strain HK803. Analysis and subsequent manipulation of plmS2 and plmR2 in the gene cluster has allowed for rational engineering of a strain that produces only one PLM analog, PLM B, at ninefold higher titers than the wild type strain. A strain producing PLM G (the penultimate intermediate in PLMs biosynthesis) has also been generated. Current work is aimed at selective in vitro acylation of PLM G with various carboxylic acids and a precursor-directed biosynthesis in a chcA deletion mutant with the aim of generating novel PLM analogs.

Cloning, Molecular↗
PubMed2003

High-performance nanocatalysts for single-step hydrogenations.

Bimetallic nanoparticles (Ru(6)Pd(6), Ru(6)Sn, Ru(10)Pt(2), Ru(5)Pt, Ru(12)Cu(4), and Ru(12)Ag(4)) anchored within silica nanopores exhibit high activities and frequently high selectivities, depending upon the composition of the nanocatalyst, in a number of single-step (and often solvent-free) hydrogenations at low temperatures (333-373 K). The selective hydrogenations of polyenes (such as 1,5,9-cyclododecatriene and 2,5-norbornadiene) are especially efficient. Good performance is found with these nanoparticle catalysts in the hydrogenation of dimethyl terephthalate to 1,4 cyclohexanedimethanol and of benzoic acid to cyclohexanecarboxylic acid or to cyclohexene-1-carboxylic acid, and also in the conversion of benzene to cyclohexene (or cyclohexane), the latter being an increasingly important reaction in the context of the production of Nylon. Isolated atoms of noble metals (Pd, Rh, and Pt) in low oxidation states, appropriately complexed and tethered to the inner walls of nanoporous (ca. 3 nm diameter) silica, are very promising enantioselective hydrogenation catalysts. Nanoporous carbons, as well as other nanoporous oxides, may also be used to anchor and tether the kind of catalysts described here.

Journal Article↗
PubMed1992

Biosynthesis of ansatrienin by Streptomyces collinus: cell-free transformations of cyclohexene- and cyclohexadienecarboxylic acids.

Cell-free extracts of Streptomyces collinus were tested with various cyclohexene- and cyclohexadienecarboxylic acids in order to determine the latter stages of the conversion of shikimic acid to cyclohexanecarboxylic acid. It was demonstrated that the final three steps of this process involve reduction of the alpha,beta-double bond of 1(6),2-cyclohexadienylcarbonyl CoA, an isomerization of the double bond of the resulting 2-cyclohexenylcarbonyl CoA to afford 1-cyclohexenylcarbonyl CoA, and a subsequent reduction of the newly formed alpha,beta-double bond. Both of the reduction steps were shown to require NADPH as a cofactor.

Anti-Bacterial Agents↗
PubMed1996

Cloning and characterization of the gene encoding 1-cyclohexenylcarbonyl coenzyme A reductase from Streptomyces collinus.

We report the cloning of the gene encoding the 1-cyclohexenylcarbonyl coenzyme A reductase (ChcA) of Streptomyces collinus, an enzyme putatively involved in the final reduction step in the formation of the cyclohexyl moiety of ansatrienin from shikimic acid. The cloned gene, with a proposed designation of chcA, encodes an 843-bp open reading frame which predicts a primary translation product of 280 amino acids and a calculated molecular mass of 29.7 kDa. Highly significant sequence similiarity extending along almost the entire length of the protein was observed with members of the short-chain alcohol dehydrogenase superfamily. The S. collinus chcA gene was overexpressed in Escherichia coli by using a bacteriophage T7 transient expression system, and a protein with a specific ChcA activity was detected. The E. coli-produced ChcA protein was purified and shown to have similar steady-state kinetics and electrophoretic mobility on sodium dodecyl sulfate-polyacrylamide gels as the enoyl-coenzyme A reductase protein prepared from S. collinus. The enzyme demonstrated the ability to catalyze, in vitro, three of the reductive steps involved in the formation of cyclohexanecarboxylic acid. An S. collinus chcA mutant, constructed by deletion of a genomic region comprising the 5' end of chcA, lost the ChcA activity and the ability to synthesize either cyclohexanecarboxylic acid or ansatrienin. These results suggest that chcA encodes the ChcA that is involved in catalyzing multiple reductive steps in the pathway that provides the cyclohexanecarboxylic acid from shikimic acid.

Amino Acid Sequence↗
PubMed1986

Tranexamic acid derivatives with enhanced absorption.

Derivatives of the antifibrinolytic drug tranexamic acid [trans-4-(aminomethyl)cyclohexanecarboxylic acid] containing one or two tranexamic acid moieties were synthesized. Most of the derivatives have good stability in acidic and neutral solutions but are easily hydrolyzed in plasma. By measuring the amount of tranexamic acid excreted in the urine after an oral dose, relative absorptions of a number of derivatives in the rat were estimated. Most of the derivatives showed greater absorption than tranexamic acid itself. 1-[(Ethoxycarbonyl)oxy]ethyl trans-4-(amino-methyl)cyclohexanecarboxylate hydrochloride was chosen for studies in man.

Animals↗
PubMed1985

Thrombin-induced alterations in lung fluid balance in awake sheep.

We examined the effect of fibrinolysis depression on thrombin-induced pulmonary microembolism in awake sheep prepared with chronic lung lymph fistulas. Fibrinolysis was depressed by an intravenous infusion (100 mg) of tranexamic acid [trans-4-(Aminomethyl)cyclohexanecarboxylic acid]. Pulmonary microembolism was induced by an intravenous infusion of alpha-thrombin (80 NIH U/kg) in normal (n = 7) and in tranexamic acid-treated (n = 6) sheep. Thrombin immediately increased pulmonary lymph flow (Qlym) in both groups. The increased Qlym was not associated with a change in the lymph-to-plasma protein concentration (L/P) ratio in the control group and with a small decrease in the tranexamic acid-treated group. The increases in Qlym and pulmonary transvascular protein clearance (Qlym X L/P ratio) in the tranexamic acid-treated group were greater and sustained at four- to fivefold above base line for 10 h after the thrombin and remained elevated at twofold above base line even at 24 h. In contrast, Qlym and protein clearance were transiently increased in the control group. The mean pulmonary arterial pressure (Ppa) and pulmonary vascular resistance (PVR) increased after thrombin in tranexamic acid-treated group; the increases in Ppa and PVR in the control group were transient. Protein reflection coefficient as determined by the filtration independent method decreased after thrombin in tranexamic acid-treated sheep (n = 5), indicating an increased vascular permeability to proteins. We conclude that prolongation of microthrombi retention in the pulmonary circulation results in an increased vascular permeability to proteins. Both increased vascular permeability and vascular hydrostatic pressure are important determinants of the increases in Qlym and transvascular protein clearance after thrombin-induced pulmonary microembolism.

Amino Acids↗
PubMed1990

Kinetics and mechanism of decomposition of N-chloroamino acids. II: conformationally restricted models.

The kinetics of decomposition of the following conformationally restricted N-chloro-alpha-amino acids were studied: 1-amino-1-cyclopentanecarboxylic acid (2), 1-amino-1-cyclohexanecarboxylic acid (4), 2-amino-2-norbornanecarboxylic acid (6), and 2-amino-2-benzonorbornanecarboxylic acid (8). The first-order rate constants obtained were 0.520, 5.197, 0.198, and 0.078, respectively, which correlated with the ring strain in the structurally related cyclic ketones cyclopentanone, cyclohexanone, norborane-2-one, and benzonorbornane-2-one. The data are supportive of a concerted mechanism for the decomposition reaction involving an imine-like transition state.

Amino Acids↗
PubMed2005

Differential effects of the 5-hydroxytryptamine (5-HT)1A receptor inverse agonists Rec 27/0224 and Rec 27/0074 on electrophysiological responses to 5-HT1A receptor activation in rat dorsal raphe nucleus and hippocampus in vitro.

The pharmacological properties of cyclohexanecarboxylic acid, {2-[4-(2-bromo-5-methoxybenzyl)piperazin-1-yl]ethyl}-(2-trifluoromethoxyphenyl)amide (Rec 27/0224), and cyclohexanecarboxylic acid, (2-methoxy-phenyl)-{2-[4-(2-methoxyphenyl)-piperazin-1-yl]ethyl}amide (Rec 27/0074), were characterized using radioligand displacement and guanosine 5'-O-(3-[35S]thiotriphosphate) ([35S]GTPgammaS) binding assays, as well as electrophysiological experiments, in rat hippocampal and dorsal raphe nucleus (DRN) slices. Both compounds showed a high affinity (Ki, approximately 1 nM) and selectivity (>70-fold) at human 5-hydroxytryptamine (5-HT)1A receptors versus other 5-HT receptors. In [35S]GTPgammaS binding assays on HeLa cells stably expressing human 5-HT1A receptors, Rec 27/0224 and Rec 27/0074 inhibited basal [35S]GTPgammaS binding by 44.8 +/- 1.7% (pEC50 = 8.58) and 25 +/- 2.5% (pEC50 = 8.86), respectively. In intracellularly recorded CA1 pyramidal cells, 5-HT1A (hetero)receptor-mediated hyperpolarization, elicited by 100 nM 5-carboxamidoytryptamine (5-CT), was partially antagonized by Rec 27/0224 (approximately 50%; IC50 = 18.0 nM) and Rec 27/0074 (74%; IC50 = 0.8 nM). In extracellularly recorded DRN serotonergic neurons, Rec 27/0224 and Rec 27/0074 fully antagonized the inhibition of firing caused by the activation of 5-HT1A (auto)receptors by 30 nM 5-CT with an IC50 of 34.9 nM and 16.5 nM, respectively. The antagonism had a slow time course, reaching a steady state within 60 min. Both compounds also antagonized the citalopram-elicited, endogenous 5-HT-mediated inhibition of cell firing. In conclusion, Rec 27/0224 and Rec 27/0074 exhibited inverse agonism in [35S]GTPgammaS binding assays and differential antagonistic properties on 5-HT1A receptor-mediated responses in the hippocampus but not in the DRN. Whether this differential effect is causally related to inverse agonist activity is unclear. The qualitatively different nature of the antagonism in the hippocampus versus the DRN clearly distinguishes the compounds from neutral antagonists, such as N-{2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl}-N-2-pyridinylcyclo-hexanecarboxamide (WAY-100635).

Animals↗