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PubMed2003

Cloning of Baeyer-Villiger monooxygenases from Comamonas, Xanthobacter and Rhodococcus using polymerase chain reaction with highly degenerate primers.

To clone novel type 1 Baeyer-Villiger monooxygenase (BVMO) genes, we isolated or collected 25 bacterial strains able to grow on alicyclic compounds. Twelve of the bacterial strains yielded polymerase chain reaction (PCR) fragments with highly degenerate primers based on the sequences of known and putative BVMOs. All these fragments were found to encode peptides homologous to published BVMO sequences. The complete BVMO genes and flanking DNA were cloned from a Comamonas, a Xanthobacter and a Rhodococcus strain using the PCR fragments as probes. BVMO genes cloned from the first two strains could be expressed to high levels in Escherichia coli using standard expression vectors, and the recombinants converted cyclopentanone and cyclohexanone to the corresponding lactones. The Rhodococcus BVMO, a putative steroid monooxygenase, could be expressed after modification of the N-terminal sequence. However, recombinants expressing this protein did not show activity towards progesterone. An esterase homologue located directly upstream of the Xanthobacter BVMO gene and a dehydrogenase homologue encoded directly downstream of the Comamonas sp. NCIMB 9872 BVMO gene were also expressed in E. coli and shown to specify lactone hydrolase and cyclohexanol dehydrogenase activity respectively.

Amino Acid Sequence↗
PubMed2002

Synthesis and antituberculosis activity of cycloalkylidenehydrazide and 4-aza-1-thiaspiro[4.5]decan-3-one derivatives of imidazo[2,1-b]thiazole.

New N2-cycloalkylidene-(6-phenyl/4-chlorophenylimidazo[2,1-b]thiazol-3-yl) acetic acid hydrazides (2a-h and 3a-b) were synthesized by reacting (6-phenyl/4-chlorophenylimidazo[2,1-b]thiazol-3-yl)acetic acid hydrazides with cyclohexanones or cyclopentanone. Furthermore, 2a-h were refluxed with thioglycolic or thiolactic acid to give 4-[[(6-phenyl/4-chlorophenylimidazo[2,1-b]thiazol-3-yl) acetyl]amino]-4-aza-1-thiaspiro[4.5]decan-3-ones (4a-h and 5a-h). The structures of the title compounds were established by spectral data (IR, 1H-NMR, 13C-NMR and EIMS (Electron Impact Mass Spectrometry)) and elemental analysis. The synthesized compounds were evaluated for antituberculosis activity against Mycobacterium tuberculosis H37Rv (ATCC 27294). The compounds exhibited varying degrees of inhibition in the in vitro primary screening that was conducted at a concentration of 6.25 micrograms/ml against M. tuberculosis H37Rv (ATCC 27294) in Bactec 12B medium using the Bactec 460 radiometric system or a broth microdilution assay, the Microplate Alamar Blue Assay (MABA). Compounds 2f, 2h, 3b, 4a, 4c, 4d, 5a-e and 5h demonstrating at 1-east 90% inhibition in the primary screen were re-tested at lower concentrations against M. tuberculosis H37Rv (ATCC 27294) to determine the actual minimum inhibitory concentration (MIC) using MABA. The most active compounds were found to be 4d and 5c. The structure-activity relationships of the derivatives were investigated.

Alkanes↗
PubMed1983

Natural sniffing gives optimum odour perception for humans.

The characteristics of human sniffing episodes during odour perception have been described in an earlier paper, where it has been suggested that the techniques used by individuals may be close to those providing optimum perception. To investigate this suggestion, threshold and intensity tests with butanol, cyclohexanone, and pentyl acetate have been carried out on twenty-one subjects. Olfactory responses obtained by using natural sniffing techniques were compared with those where the number of sniffs, interval between sniffs, and size of sniffs were varied. The results indicate that it is very difficult to improve on the efficiency of sniffing techniques of individuals and that a single natural sniff provides as much information about the presence and intensity of an odour as do seven or more sniffs. A single natural sniff and the first sniff of a a natural sniffing episode were shown to have similar characteristics and most significantly both were unaffected by changes in the concentration and type of odour. Overall, the results indicate that humans achieve optimum odour perception during threshold and intensity measures with their natural multiple-sniff technique or with a single sniff. For the 'average' human this occurs with a sniff of inhalation rate 30 1 min-1, volume 200 cm3, and duration 0.4 s. The use of several sniffs in a sniffing episode appears to be a confirmatory action rather than a necessary one, except for the perception of odour mixtures where several sniffs are likely to be needed to aid discrimination of the components. Data from the present and earlier study provide the information necessary for the development of a standard olfactometer and standard procedures for measuring the olfactory responses of humans.

Adult↗
PubMed2001

Functional expression and characterization of a Drosophila odorant receptor in a heterologous cell system.

Odorant receptors (ORs) constitute the molecular basis for the detection of volatile odorous molecules and the perception of smell. Our understanding of chemical senses has been greatly expanded by the discovery of the OR gene families in vertebrates and in the nematode Caenorhabditis elegans. Recently, candidate Drosophila OR genes have been identified. The putative ORs do not possess any primary sequence identity with known vertebrate or C. elegans receptors, but belong to the family of G protein-coupled receptors according to their predicted seven transmembrane topology. To prove olfactory function of these proteins, we expressed a member of the putative Drosophila OR gene family, Or43a, in Xenopus laevis oocytes. Using two-electrode voltage-clamp recording we identified four odors (cyclohexanone, cyclohexanol, benzaldehyde, and benzyl alcohol) that activated the receptor at low micromolar concentration and structurally related substances that did not. This report shows the function and specificity of a member of the recently identified family of Drosophila ORs expressed in a heterologous system.

Animals↗
PubMed1992

Insulin-like growth factor I gene expression is induced in astrocytes during experimental demyelination.

To investigate insulin-like growth factor I (IGF-I) and IGF-I receptor gene expression during experimental demyelination and myelin regeneration, young mice were fed cuprizone (( bis(cyclohexanone) oxaldihydrazone )). This copper-chelating agent produces demyelination in the corpus callosum and superior cerebellar peduncles, and when treatment is stopped, there is rapid remyelination. At intervals during cuprizone treatment and recovery, brain sections were hybridized with specific probes and immunostained with antibodies to determine the localization and relative amounts of IGF-I and IGF-I receptor mRNAs and peptides. In untreated littermates, IGF-I and IGF-I receptor mRNAs and peptides were not detected in white matter. In cuprizone-treated mice, high levels of both IGF-I mRNA and peptide were expressed by astrocytes in areas of myelin breakdown. Astrocyte IGF-I expression decreased rapidly during recovery and oligodendroglial expression of myelin-related genes increased. In severely demyelinated areas, immature oligodendroglia exhibited a transient increase in IGF-I receptor mRNA and peptide immunoreactivity during early recovery. This highly specific pattern of IGF-I induction in astrocytes during demyelination and the expression of the IGF-I receptor in regenerating oligodendrocytes during recovery suggest that IGF-I functions in the regulation of oligodendrocyte and myelin metabolism in vivo.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1999

The AcbC protein from Actinoplanes species is a C7-cyclitol synthase related to 3-dehydroquinate synthases and is involved in the biosynthesis of the alpha-glucosidase inhibitor acarbose.

The putative biosynthetic gene cluster for the alpha-glucosidase inhibitor acarbose was identified in the producer Actinoplanes sp. 50/110 by cloning a DNA segment containing the conserved gene for dTDP-D-glucose 4,6-dehydratase, acbB. The two flanking genes were acbA (dTDP-D-glucose synthase) and acbC, encoding a protein with significant similarity to 3-dehydroquinate synthases (AroB proteins). The acbC gene was overexpressed heterologously in Streptomyces lividans 66, and the product was shown to be a C7-cyclitol synthase using sedo-heptulose 7-phosphate, but not ido-heptulose 7-phosphate, as its substrate. The cyclization product, 2-epi-5-epi-valiolone ((2S,3S,4S,5R)-5-(hydroxymethyl)cyclohexanon-2,3,4,5-tetrol), is a precursor of the valienamine moiety of acarbose. A possible five-step reaction mechanism is proposed for the cyclization reaction catalyzed by AcbC based on the recent analysis of the three-dimensional structure of a eukaryotic 3-dehydroquinate synthase domain (Carpenter, E. P., Hawkins, A. R., Frost, J. W., and Brown, K. A. (1998) Nature 394, 299-302).

Acarbose↗
PubMed1998

Migration from polyamide 'microwave and roasting bags' into roast chicken.

Migration of non-volatile and volatile compounds from 'microwave and roasting bags' (MRB), made of Nylon 6,6 (and some Nylon 6), into chicken meat, skin, and juices during roasting (200 degrees C/2 h) in a conventional oven was determined. For measurement of migration of non-volatile compounds, cooked chicken was freeze-dried, extracted with methanol after addition of 2-azacyclononane (internal standard) and the extract cleaned-up using liquid-solid adsorption chromatography (silica gel). High performance liquid chromatography (HPLC) in the reverse phase mode using a linear gradient of methanol in water was used to quantify seven Nylon 6 and Nylon 6,6 cyclic monomers and oligomers of molecular mass up to 678 daltons. Migration into chicken was 7.48 micrograms/g (8.26 mg/bag; 3.94 micrograms/cm2), 16% of the total non-volatile compounds contained in the MRB material. Individual migrants were also quantified. Migration of one volatile compound, 2-cyclopentyl cyclopentanone, into the roast chicken parts was measured. Extraction with diethyl ether, using a modified Likens-Nickerson system of concurrent steam distillation-solvent extraction with an internal standard (cyclohexanone) was performed for 10 h. Gas chromatography/mass spectrometry (GC/MS) in the selected ion mode (SIM) was used for quantification. An average of 14.0 (+/- 4.36) micrograms/bag (or micrograms/chicken) migrated, being 0.08% of the total 2-cyclopentyl cyclopentanone present in MRB. Loss of volatile compounds to the atmosphere is believed to have occurred since there was another, more volatile compound (cyclopentanone), present in MRB, at levels higher than 2-cyclopentyl cyclopentanone, but this was not detected in roast chicken. In general, the transference of MRB components into roast chicken can be considered not to present a hazard.

Animals↗
PubMed2000

Identification of potential hazards associated with new residential construction.

There were several advantages and limitations of this observational study. The most important advantage of this study was the opportunity to observe residential construction workers performing their jobs. By observing work practices, valuable information was gathered about specific trades and their potential exposure to various chemical and physical agents. This information will be useful in guiding subsequent exposure assessments. Probably the greatest limitation of this study was the lack of participation by homebuilders. Ideally, observations of construction processes would have been more objective if the study included the participation of more than one homebuilder. Aside from one worker who was observed to wear safety glasses, leather gloves, and a dust mask, virtually no personal protective equipment (PPE) was observed onsite. Often small contractors do not have the financial resources necessary to procure the appropriate PPE and issue these items to the workers. Based on hazard prevalence, professional judgement, and the degree of hazardous product use, potential exposures that warrant quantitative sampling efforts during Phase 2 of this study are: bulldozer/backhoe operators--noise, vibration, diesel exhaust; concrete workers--naphtha, mineral spirits, Portland cement; asphalt workers--petroleum hydrocarbons, asphalt, mineral spirits; plumbers--methylethyl ketone, acetone, tetrahydrofuran, cyclohexanone; drywall finishers--total and respirable dust, hexane, acetone; painters--ethylene glycol, VOCs; masons--dust (during the preparation of mortar); floor preparation technicians--total and respirable dust; and ceramic tile installers--toluene, naphtha, silica (from grout powder).

Air Pollution↗
PubMed2000

Regulated workplace ketones and their interference in the PFBHA method for aldehydes.

Ketones are the major positive interferences for an aldehyde dynamic air sampler that consists of 200-mg 20 percent (w/w) O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) on Tenax TA contained in a Pyrex tube 7-mm OD, 5-mm ID, and 70-mm in length, that utilizes a personal battery-powered pump at 10-50 mL/min. The ketone O-oxime derivatives were synthesized to allow absolute quantitation of O-oximes formed during sampling. Wet spiking allowed ketone recoveries to be found. Ketone vapors of known concentrations were generated statically in Tedlar gas bags. The O-oximes were desorbed with hexane, and an aliquot injected for gas chromatographic analysis on a nonpolar capillary column with mass spectrometric or electron capture detection. Gas phase recoveries up to 200 ppm-hour loadings exceeded 75 percent at 25 degrees C for chloroacetone, cyclohexanone, diacetone alcohol, diethyl ketone, dipropyl ketone, ethyl butyl ketone, methyl amyl ketone, methyl butyl ketone, 2-methylcyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, methyl isopropyl ketone, and methyl propyl ketone. The recoveries for acetophenone, 2-chloroacetophenone, and ethyl amyl ketone were lower than 75 percent, and were caused by steric hindrance. Sampling for both aldehydes and ketones is recommended at 10 mL/min for TLV concentrations.

Air Pollution, Indoor↗
PubMedDate not supplied

A new passive sampler for regulated workplace ketones.

A new solid sorbent passive air sampler for ketones has a silicone membrane atop a diffusion cylindrical path length of 1.1 cm and diameter 1.3 cm above a pellet of Tenax TA coated with 10% (w/w) O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride. Vapors of known concentrations approximating their workplace permissible exposure limits of Occupational Safety and Health Administration-regulated ketones at a relative humidity (RH) of 3 +/- 1% were generated by a syringe pump connected to a dynamic air dilution system connected to an exposure chamber that allowed measurement of face velocities, temperatures, exposing vapor concentrations, and RHs. The O-oxime derivative was desorbed with hexane, and an aliquot injected for gas chromatographic analysis on a nonpolar capillary column by mass spectrometric or electron capture detection. The experimental passive sampler sampling rates in milliliters per minute at 25 degrees C were 4.07 +/- 0.49, cyclohexanone; 6.30 +/- 0.59, diethyl ketone; 6.31 +/- 0.31, ethyl n-butyl ketone; 3.78 +/- 0.25, methyl n-amyl ketone; 3.43 +/- 0.19, methyl n-butyl ketone; 6.48 +/- 0.64, methyl ethyl ketone; 4.37 +/- 0.43, methyl isopropyl ketone; and 4.57 +/- 0.17, methyl n-propyl ketone. These preliminary data show that sterically unhindered ketones can be sampled by the passive sampler as well as aldehydes.

Chromatography, Gas↗
PubMed1989

Capillary GC analysis of compounds leached into parenteral solutions packaged in plastic bags.

A number of investigators have reported finding the plasticizer di(2-ethylhexyl)phthalate in plasma, urine, and parenteral solutions. These findings have been associated with the use of polyvinyl chloride packaging materials. Capillary gas chromatography--mass spectrometry, packed column gas chromatography, and high-performance liquid chromatography were used for the analyses. The screening procedure described herein accurately and quantitatively analyzes the plasticizers di(2-ethylhexyl)phthalate and dibutylphthalate and some of the degradation products plus 2,6-di-tert-butyl-p-cresol and cyclohexanone. Liquid--liquid extraction followed by capillary gas chromatography is used. Linear regression analysis of standard solutions gives correlation coefficients from 0.99963 to 0.99989 for six compounds. Recoveries for these compounds vary from 84.9% to 114% with relative standard deviations ranging from 2.51% to 6.33%.

Chromatography, Gas↗
PubMedDate not supplied

Pyrolytic fate of piperidinocyclohexanecarbonitrile, a contaminant of phencyclidine, during smoking.

The pyrolysis products of 1-(1-piperidino)cyclo-hexanecarbonitrile (PCC), the major contaminant of illicit phencyclidine (PCP), have not been previously reported. In order to quantify PCC in mainstream smoke as well as to identify the pyrolysis products, [3H]piperidino-[14C]cyano-PCC was synthesized. Marijuana placebo cigarettes were impregnated with this double-labeled PCC and burned with an apparatus that simulated smoking. The mainstream smoke was passed through a series of traps containing glass wool, H2SO4, or NaOH. Approximately 75% of the 3H was collected in these traps, and 46, 11, and 5% of the 14C was found in the glass wool, H2SO4, and NaOH traps, respectively. Contents of the traps were analyzed by GC/MS. The glass wool trap contained 1-(1-piperidino)-1-cyclo-hexene, PCC, piperidine, and N-acetylpiperidine, and cyanide ion was detected in all three traps. Approximately 47% of the PCC was found intact in mainstream smoke. Approximately 58% was cleaved to form cyanide and 1-(1-piperidino)-1-cyclohexene. The latter was further broken down to cyclohexanone (which represented 21% of the starting material), piperidine (29%), and N-acetylpiperidine (7%), and about 2% remained intact.

Drug Contamination↗
PubMed1999

Steroid monooxygenase of Rhodococcus rhodochrous: sequencing of the genomic DNA, and hyperexpression, purification, and characterization of the recombinant enzyme.

Steroid monooxygenase of Rhodococcus rhodochrous is a Baeyer-Villigerase catalyzing the insertion of an oxygen atom between the C(17)- and C(20)-carbons of progesterone to produce testosterone acetate. The 5.1-kbp-long BamHI DNA fragment containing the steroid monooxygenase gene, smo, was cloned from the chromosomal DNA and sequenced. The smo gene is 1,650 nucleotides long, starts with a TTG codon, and ends with a TGA codon. The deduced amino acid sequence indicates that the enzyme protein consist of 549 amino acid residues with a molecular mass of 60,133. Thus, the molecular mass of the holoenzyme is 60,919. The amino acid sequence is highly homologous (41.2% identity) to that of cyclohexanone monooxygenase of Acinetobacter sp. In the upstream of the smo gene, the genes of heat shock proteins, dnaK, grpE, and dnaJ, located on the complementary strand, and the DNA-inserts of pSMO and pD1, which contains the ksdD gene, were joined at the BamHI site of the dnaJ gene. The smo gene was modified at the initiation codon to ATG and ligated with an expression vector to construct a plasmid, pSMO-EX, and introduced into Escherichia coli cells. The transformed cells hyperexpressed the steroid monooxygenase as an active and soluble protein at more than 40 times the level in R. rhodochrous cells. Purification of the recombinant monooxygenase from the E. coli cells by simplified procedures yielded about 2.3 mg of enzyme protein/g wet cells. The purified recombinant steroid monooxygenase exhibited indistinguishable molecular and catalytic properties from those of the R. rhodochrous enzyme.

Amino Acid Sequence↗
PubMed1977

Purification and some properties of cyclohexylamine oxidase from a Pseudomonas sp.

Cyclohexylamine oxidase was purified 90-fold from cell-free extracts of Pseudomonas sp. capable of assimilating sodium cyclamate. The purified enzyme was homogeneous in disc electrophoresis, and the molecular weight was found to be approximately 80,000 by gel filtration. The enzyme catalyzed the following reaction: cyclohexylamine+O2+H2O leads to cyclohexanone+NH3+H2O2. The enzyme thus can be classified as an amine oxidase; it utilized oxygen as the ultimate electron acceptor. The pH optimum of the reaction was 6.8 and the apparent Km value for cyclohexylamine was 2.5 X 10(-4) M. The enzyme was highly specific for the deamination of alicyclic primary amines such as cyclohexylamine, but was found to be inactive toward ordinary amines used as substrates for amine oxidases. The enzyme solution was yellow in color and showed a typical flavoprotein spectrum; the addition of cyclohexylamine under anaerobic conditions caused reduction of the flavin in the native enzyme. The flavin of the prosthetic group was identified as FAD by thin layer chromatography. The participation of sulfhydryl groups in the enzymic action was also suggested by the observation that the enzyme activity was inhibited in the presence of PCMB and could be recovered by the addition of glutathione.

Amines↗
PubMed1979

Purification and properties of reductases for aromatic aldehydes and ketones from guinea pig liver.

NADPH-dependent enzymatic reduction of aromatic aldehydes and ketones observed in the cytosol of guinea pig liver was mediated by at least three distinct reductases (AR 1, AR 2, and AR 3), which were separated by DEAE-cellulose chromatography. By several procedures AR 2 and AR 3 were purified to homogeneity, but AR 1 could be purified only 30-fold because of the small amount. These enzymes were found to have similar molecular weights of 34,000 to 36,000 and similar Stokes radii of about 2.5 nm. AR 3 was identical to aldehyde reductase [EC 1.1.1.2] in substrate specificity for aromatic aldehydes and D-glucuronate and specific inhibition by barbiturates. AR 1 and AR 2 acted on aromatic ketones and cyclohexanone as well as aromatic aldehydes at optimal pHs of 5.4 and 6.0, respectively, and were immunochemically distinguished from AR 3. AR 1 was the most sensitive to sulfhydryl reagents, and AR 2 was more stable at 50 degrees C than the other enzymes. Similar heterogeneity was observed in the kidney enzymes, but other tissues had little aldehyde reductase activity and contained only AR 3. In addition, lung contained a high molecular weight aromatic ketone reductase different from the above reductases.

Aldehyde Oxidoreductases↗
PubMed2000

(2R,3R,5R)-2-

The molecular structures of two chiral cyclohexanones based on R-(-)-carvone, C(17)H(26)O(3), (I), and C(17)H(23)NO, (II), are reported here. The six-membered ring in (I) is in a chair conformation with the two fused five-membered rings of the furofuranyl substituent in a cis configuration. Compound (II) contains a decalin group; one ring has the chair form whilst the other is in a half-boat conformation. Both products have been characterized spectroscopically, however, neither NMR nor IR results could prove the stereochemistry at each chiral centre unambiguously. The crystal analyses were used to examine conformational properties of the compounds.

Journal Article↗
PubMed2001

4-Ethoxycarbonyl-3-hydroxy-3-phenylcyclohexanone.

The title compound, ethyl 2-hydroxy-4-oxo-2-phenylcyclohexanecarboxylate, C(15)H(18)O(4), was obtained by a Michael-Aldol condensation and has the cyclohexanone in a chair conformation. The attached hydroxy, ethoxycarbonyl and phenyl groups are disposed in beta-axial, beta-equatorial and alpha-equatorial configurations, respectively. An intermolecular hydrogen bond, with an O.O distance of 2.874 (2) A, links the OH group and the ring carbonyl. Weak intermolecular C-H.O=C (ester and ketone), O-H.O=C (ketone) and C-H.OH hydrogen bonds exist.

Journal Article↗
PubMed2001

2,9-bis(3-nitrophenyl)-1-azaadamantan-4-one.

The title compound, 2,9-bis(3-nitrophenyl)-1-azatricyclo[3.3.1.1(3,7)]decan-4-one, C21H19N3O5, has a tricyclic structure. The torsion angles may be used to describe the relationship of the carbonyl group to the adjacent faces, whereby it is seen that the angles on the face of the arylpiperidinone side [122.0 (3) and -122.0 (3) degrees ] are greater than those on the cyclohexanone side [-119.8 (4) and 119.9 (4) degrees ]. Although these differences may explain a facial selectivity during nucleophilic addition to the carbonyl group, the presence of the aryl rings is probably also important.

Journal Article↗