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PubMedDate not supplied

[Experimental study of the toxic convulsant properties of commercial preparations of essences of sage and hyssop (author's transl)].

Commercial preparations of essences of sage and hyssop have caused poisoning of human beings and were found to possess a convulsant action of central origin in animals. The convulsant effect of hyssop essence appears to be more powerful than that of sage in non-anaesthetized rats. The dose limit, below which the cortical phenomena are subclinical, is 0.08 g/kg for hyssop, while above 0.13 g/kg convulsions appear and become lethal above 1.25 g/kg. The same doses for essence of sage are respectively 0.3, 0.5 and 3.2 g/kg. The neurotoxicity of hyssop appears to be related to the presence of two terpene ketones, pinocamphone and isopinocamphone, the former of which has powerful convulsant properties, and is lethal at doses above 0.05 ml/kg. The toxicity of essence of sage is due to the presence of camphor which is well-known to possess convulsant properties.

Animals↗
PubMed2003

Effect of camphor/cyclodextrin complexation on the stability of O/W/O multiple emulsions.

Camphor (CA) encapsulation in oil/water/oil multiple emulsions prepared with cyclodextrin disturbs the emulsifier potential of alpha- and beta-natural cyclodextrins (CD). It was suggested that the size and geometrical fit between the CD cavity and CA could induce CD/CA complex formation in place of emulsifier formation leading to perturbation of emulsion stability. The complexation between CA and alpha-, beta- or gamma-CD in solution in the presence of oil phase are confirmed by phase-solubility diagrams, circular dichroism and 1H NMR. Furthermore, in order to mimic the emulsion system, CD/CA/soybean oil ternary dispersions were prepared to observe the complexation behavior of alpha-, beta- or gamma-CD/CA by circular dichroism. X-ray diffraction on emulsion samples prepared with alpha- and beta-CD confirms that the precipitates observed in emulsions are probably composed of crystals of CD/CA complexes. A preliminary study of the interaction between drug and CD before the formulation seems indispensable to prevent the risk of incompatibility.

Camphor↗
PubMed1994

Conformationally constrained o-tolylpiperazine camphorsulfonamide oxytocin antagonists. Structural modifications that provide high receptor affinity and suggest a bioactive conformation.

A series of new o-tolylpiperazine camphorsulfonamide OT antagonists is described. Analogs containing conformationally constrained 1-acylamino-2-propyl substituents at the camphor C2 endo position exhibit high affinity for OT and AVP-V1a receptors or high affinity and selectivity for OT receptors, depending on functionalities present in the acyl group. Determination of the preferred conformation of potency-enhancing 1-acylamino-2-propyl substituents using molecular mechanics energy calculations and X-ray crystallography, along with topological similarities to a conformationally constrained cyclic hexapeptide OT antagonist, suggests a receptor-bound conformation for this series of non-peptide OT antagonists.

Amino Acid Sequence↗
PubMed2003

Calcium hydroxide's association with different vehicles: In vitro action on some dentinal components.

OBJECTIVE: Calcium hydroxide, Ca(OH)(2), is a common intracanal medicament. Ca(OH)(2) powder can be mixed with different vehicles and used as a paste for temporary intracanal treatment. The vehicle may influence the dissociation of calcium hydroxide into ions. We sought to evaluate the level of pH and to quantitatively estimate the release of proteins, hydroxyproline, and phosphorus from pieces of radicular dentin kept in different Ca(OH)(2) solutions. STUDY DESIGN: Twenty-eight extracted incisors were maintained for 35 days in Ca(OH)(2) aqueous solutions prepared in chlorhexidine digluconate, propylene glycol (PG), anesthetic solution, camphorated monochlorophenol (CMCP), and CMCP-PG. The control solution contained Ca(OH)(2) without vehicle. RESULTS: The pH values changed little during the experiment. The concentrations of proteins, hydroxyproline, and phosphorus rose for all the solutions under study. Statistical analysis of the data from the control and the experimental groups revealed an increase in the concentration of proteins when chlorhexidine, anesthetic solution, and PG were used; a rise in hydroxyproline levels when CMCP-PG, CMCP, and PG solutions were used; and an increase in phosphorus when PG and chlorhexidine vehicles were used. CONCLUSION: The test solutions with the root dentin remained alkaline. A release of proteins, hydroxyproline, and phosphorus was observed.

Analysis of Variance↗
PubMed1995

Effect of four vehicles on the pH of calcium hydroxide and the release of calcium ion.

Nonsetting calcium hydroxide pastes are commonly used in endodontic practice. The desired therapeutic effect of such a paste is in part dependent on the dissociation of calcium hydroxide into hydroxy ion and calcium ion. This in turn is influenced by the vehicle used to make the paste. This investigation attempts to quantitatively estimate the release of hydroxyl ion and calcium ion from pastes made by using distilled water, normal saline solution, camphorated monochlorophenol and also an experimental vehicle, propylene glycol. The results of this study indicate that propylene glycol induces the most favorable release characteristics of the two ionic species.

Calcium↗
PubMed1994

Universal spectropolarimeter based on overtone circular dichroism measurements in the near-infrared region.

A novel and highly sensitive circular dichroism spectropolarimeter for the near-infrared region has been developed. In this instrument, a solid state titanium-sapphire laser that can be spectrally tuned from 670 to 1030 nm was used as the light source. The laser beam was converted into linearly polarized light by a polarizer and into left circularly polarized light and right circularly polarized light at 42 kHz by a photoelastic modulator (PEM). A limit of detection of 1.1 x 10(-6) AU was achieved by this instrument for (+)-Co(en)3(3+) at 765 nm. Further improvement including employing double modulation (at 42 kHz by the PEM and at 85 Hz by a chopper just before the laser beam was converted to CPL), demodulating and amplifying the signal with high-performance lock-in amplifiers, was made to enable the instrument to have the required sensitivity for the measurements of the circular dichroism of overtones and combination transitions of saturated chiral compounds, e.g., (R)- and (S)-camphor, (R)- and (S)-2-octanol, and (R)- and (S)-2-amino-1-octanol. Because the measured CD spectra originate from the overtones and combination transitions of the C-H and O-H groups, the spectropolarimeter can be used to detect virtually any compounds that have O-H and/or C-H groups.

Aluminum Oxide↗
PubMed2004

Determination of enantiomeric excess in samples of chiral molecules using fourier transform vibrational circular dichroism spectroscopy: simulation of real-time reaction monitoring.

The first use of Fourier transform vibrational circular dichroism (FT-VCD) to follow changes in the percent enantiomeric excess (% EE) of chiral molecules in time using a flow cell sampling apparatus is reported. FT-VCD, as opposed to dispersive scanning VCD, eliminates the need to scan the VCD spectrum in time to monitor the % EE at more than one spectral location. The first use of partial least-squares chemometric analysis to determine % EE values from kinetic sets of VCD spectral data is also reported. These two advances have been used to monitor simultaneously changes in the fractional composition and the % EE of a mixture of two different chiral molecules. This simulates the progress of the chemical reaction from a chiral reactant to a chiral product where the % EE of both molecules can change with time. For the molecules studied, alpha-pinene, camphor, and borneol, the accuracy of following % EE changes for one species alone is approximately 1%, while for simultaneously following % EE changes in two species is approximately 2% for 10-20-min sampling periods at 4 cm(-)(1) spectral resolution. This accuracy can be increased for the same collection times or maintained for shorter periods of collection by lowering the spectral resolution. These findings demonstrate the potential for VCD to be used for real-time monitoring of the composition and % EE of chemical reactions involving the synthesis chiral molecules.

Bicyclic Monoterpenes↗
PubMed1991

Crystal structure of the cytochrome P-450CAM active site mutant Thr252Ala.

The crystal structure of a cytochrome P-450CAM site-directed mutant in which the active site Thr252 has been replaced with an Ala (Thr252Ala) has been refined to an R factor of 0.18 at 2.2 A. According to sequence alignments (Nelson & Strobel, 1989), Thr252 is highly conserved among P-450 enzymes. The crystallographic structure of ferrous camphor- and carbon monoxide-bound P-450CAM (Raag & Poulos, 1989b) suggests that Thr252 is a key active site residue, forming part of the dioxygen-binding site. Mutation of the active site threonine to alanine produces an enzyme in which substrate hydroxylation is uncoupled from electron transfer. Specifically, hydrogen peroxide and "excess" water are produced instead of the product, 5-exo-hydroxycamphor. The X-ray structure has revealed that a local distortion in the distal helix between Gly248 and Thr252 becomes even more severe in the Thr252Ala mutant. Furthermore, a solvent molecule not present in the native enzyme is positioned in the dioxygen-binding region of the mutant enzyme active site. In this location, the solvent molecule could sterically interfere with and destabilize dioxygen binding. In addition, the active site solvent molecule is connected, via a network of hydrogen bonds, with an internal solvent channel which links distal helix residues to a buried Glu side chain. Thus, solvent protons appear to be much more accessible to dioxygen in the mutant than in the wild-type enzyme, a factor which may promote hydrogen peroxide and/or water production instead of substrate hydroxylation. On the basis of crystallographic and mutagenesis data, a proton delivery pathway involving residues Lys178/Arg186, Asp251, and Thr252 is proposed for wild-type P-450CAM. Coordinates of structures discussed in this paper have been submitted to the Brookhaven Protein Data Bank (Bernstein et al., 1977).

Alanine↗
PubMed1987

Temperature jump relaxation kinetics of the P-450cam spin equilibrium.

The ferric spin-state equilibrium and relaxation rate of cytochrome P-450 has been examined with temperature jump spectroscopy using a number of camphor analogues known to induce different mixed spin states in the substrate-bound complexes [Gould, P., Gelb, M., & Sligar, S. G. (1981) J. Biol. Chem. 256, 6686]. All temperature-induced spectral changes were monophasic, and the spin-state relaxation rate reached a limiting value at high substrate concentrations. The ferric spin equilibrium constant, Kspin, is defined in terms of the rate constants k1 and k-1 via Kspin = k1/k-1 = [P-450(HS)]/[P-450(LS)] where HS and LS represent high-spin (S = 5/2) and low-spin (S = 1/2) ferric iron, respectively, and the spectrally observed spin-state relaxation rate by kobsd = k1 + k-1. A strong correlation between the fraction of high-spin species and the rate constant, k-1, is observed. For a 3 degrees C temperature jump (from 10 to 13 degrees C), the 23% high-spin tetramethylcyclohexanone complex (Kd = 45 +/- 20 microM) is characterized by a ferric spin relaxation rate of kobsd = 1990 s-1, while the rates for the d-fenchone (41% high spin, Kd = 42 +/- 10 microM) and kobsd = 1990 s-1, while the rates for the d-fenchone (41% high spin, Kd = 42 +/- 10 microM) and camphoroquinone (75% high spin, Kd = 15 +/- 5 microM) complexes are 1430 and 346 s-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Camphor 5-Monooxygenase↗
PubMed1988

Deuterium isotope effects in norcamphor metabolism by cytochrome P-450cam: kinetic evidence for the two-electron reduction of a high-valent iron-oxo intermediate.

The kinetics of NADH consumption, oxygen uptake, and hydrogen peroxide production have been studied for norcamphor metabolism by cytochrome P-450cam. The kinetic deuterium isotope effects on these processes, with specifically deuteriated norcamphor, are 0.77, 1.22, and 1.16, respectively. Steady-state UV-visible spectroscopy indicates that transfer of the second electron to the dioxy ferrous P-450 is the rate-limiting step, as it is when camphor is the substrate. The inverse deuterium isotope effect for NADH consumption is consistent with an isotope-dependent branching between monooxygenase and oxidase activity, where these reactivities differ in their NADH:oxygen stoichiometries. However, no isotope-dependent redistribution of steady-state intermediates was detected by isotopic difference UV-visible spectroscopy in the presence of norcamphor. The kinetic isotope effects and steady-state spectral results suggest that the high-valent iron-oxo hydroxylating intermediate [FeO]3+ is reduced by NADH and the physiological electron-transfer proteins to afford water.

Camphor 5-Monooxygenase↗
PubMed2006

Putidaredoxin-to-cytochrome P450cam electron transfer: differences between the two reductive steps required for catalysis.

Cytochrome P450cam (P450cam) is the terminal monooxygenase in a three-component camphor-hydroxylating system from Pseudomonas putida. The reaction cycle requires two distinct electron transfer (ET) processes from the [2Fe-2S] containing putidaredoxin (Pdx) to P450cam. Even though the mechanism of interaction and ET between the two proteins has been under investigation for over 30 years, the second reductive step and the effector role of Pdx are not fully understood. We utilized mutagenesis, kinetic, and computer modeling approaches to better understand differences between the two Pdx-to-P450cam ET events. Our results indicate that interacting residues and the ET pathways in the complexes formed between reduced Pdx (Pdx(r)) and the ferric and ferrous dioxygen-bound forms of P450cam (oxy-P450cam) are different. Pdx Asp38 and Trp106 were found to be key players in both reductive steps. Compared to the wild-type Pdx, the D38A, W106A, and delta106 mutants exhibited considerably higher Kd values for ferric P450cam and retained ca. 20% of the first electron transferring ability. In contrast, the binding affinity of the mutants for oxy-P450cam was not substantially altered while the second ET rates were <1%. On the basis of the kinetic and modeling data we conclude that (i) P450cam-Pdx interaction is highly specific in part because it is guided/controlled by the redox state of both partners; (ii) there are alternative ET routes from Pdx(r) to ferric P450cam and a unique pathway to oxy-P450cam involving Asp38; (iii) Pdx Trp106 is a key structural element that couples the second ET event to product formation possibly via its "push" effect on the heme-binding loop.

Amino Acid Substitution↗
PubMed1997

Exceptionally stable salt bridges in cytochrome P450cam have functional roles.

A long-standing puzzle in structure-function studies of cytochrome P450cam is how the substrate, camphor, reaches the buried active site. The crystal structure shows no channel from the surface to the active site large enough for substrate to pass through. Recent experiments indicate that access of the rather nonpolar substrate to the active site is controlled by electrostatic interactions and may involve rupture of the two salt links to Asp251 [Deprez, E., Gerber, N. C., Di Primo, C., Douzou, P., Sligar, S. G., & Hui Bon Hoa, G. (1994) Biochemistry 33, 14464-14468]. Consequently, we have computed the electrostatic strength of 53 ionic pairs, including 32 salt links, in cytochrome P450cam by numerical solution of the finite-difference linearized Poisson-Boltzmann equation. The calculated electrostatic free energies, delta Gtot, of the salt links range from -9 to +6 kcal/mol with approximately 60% of the salt links being energetically favorable and 40% being unfavorable with respect to mutation to their uncharged, nonpolar isosteres. Strikingly, of the four most stable salt links in the protein (delta Gtot < -6 kcal/mol), two involve the propionate groups of the heme and the other two involve Asp251. In the modeled D251N mutant, for which electrostatic effects on substrate binding are diminished, the latter two salt links lose their stability (delta Gtot > -2.4 kcal/mol). Thus it appears that cytochrome P450cam has evolved four unusually strong salt bridges, stabilized by surrounding charged and polar groups in the protein, to keep its heme cofactor in place and to regulate substrate binding.

Binding Sites↗
PubMed1997

Comparative Fourier transform infrared studies of the secondary structure and the CO heme ligand environment in cytochrome P-450cam and cytochrome P-420cam.

For the first time, Fourier transform infrared spectroscopy has been applied to cytochrome P-450 to analyze the protein secondary structure. From Fourier self-deconvolution and fitting the infrared spectra in the amide I' region (1600-1700 cm-1), we estimate 44% alpha-helix, 31% beta-sheet, and 18% turns for substrate-free cytochrome P-450cam. In the presence of camphor, 54% alpha-helix and 310-helix, 21% beta-sheet, and 21% turns are obtained which agree with the crystallographic data of 53% alpha-helix, 19% beta-sheet, and 16% turns [Poulos, T. L., Finzel, B. C., & Howard, A. J. (1987) J. Mol. Biol. 195, 687-700]. Cytochrome P-420cam is produced from substrate-free cytochrome P-450cam in two ways: (i) by temperature elevation up to 60 degrees C and (ii) by exposure to KSCN up to 1.5 M. The secondary structure composition is determined for each temperature and KSCN concentration and compared with the changes observed in the iron ligand CO stretch vibration bands appearing between 1900 and 2000 cm-1. Thermally induced cytochrome P-420 has an alpha-helix content of 19%, a beta-sheet content of 53%, 14% turns, and 5% antiparallel beta-sheets from intermolecular hydrogen bonds within protein aggregates. The formation of cytochrome P-420 as a function of the KSCN concentration indicates two types of cytochrome P-420. Up to 1 M KSCN, the induced cytochrome P-420 displays only little modification of the secondary structure, whereas at 1.5 M KSCN, larger changes are observed, resulting in 85% cytochrome P-420 without protein precipitation and containing 30% alpha-helix, 48% beta-sheet, and 17% turns. Infrared spectra in the iron ligand CO stretch region show several subconformers for cytochrome P-420. During the cytochrome P-420 formation, the CO stretch modes are shifted to higher frequencies by 3-11 cm-1, with a main feature at about 1964 cm-1, compared to those of substrate-free cytochrome P-450cam-CO.

Binding Sites↗
PubMed1999

Deuterium magic angle spinning studies of substrates bound to cytochrome P450.

We report solid-state deuterium magic angle spinning NMR spectra of perdeuterated adamantane bound to the active site of microcrystalline cytochrome P450cam (CP450cam) in its resting state. CP450cam contains a high-spin ferric (Fe3+) heme in the resting state; the isotropic shift was displaced from the diamagnetic value and varied with temperature consistent with Curie-law dependence. A nondeuterated competitive tighter binding ligand, camphor, was used to displace the adamantane-bound species. This addition resulted in the disappearance of the hyperfine-shifted signal associated with a perdeuterated adamantane bound to CP450cam, while signals presumably associated with adamantane bound to other cavities persisted. We simulated the deuterium spinning side-band intensities for the enzyme-bound species using dipolar hyperfine coupling as the only anisotropic interaction; the deuterium quadrupolar interaction was apparently averaged due to a fast high-symmetry motion. These data provide direct support for previous proposals that substrates are conformationally mobile on the time scale of enzymatic turnover. The simulations suggested that the adamantane binds with an average metal-deuterium distance of 6.2 (+/-0.2) A, corresponding to a dipolar coupling constant of 6.5 (+/-0.5) kHz.

Adamantane↗
PubMedDate not supplied

Luciferase-dependent, cytochrome P-450-catalyzed dehalogenation in genetically engineered Pseudomonas.

To investigate the possibility of luciferase-dependent photoreduction of cytochrome P-450's in vivo, Vibrio harveyi luciferase was coexpressed with the bacterial cytochrome P-450cam in Pseudomonas putida. Luciferase expression was under the control of the Pm promoter from the meta-cleavage TOL operon, incorporated into the chromosome by a mini Tn5-mediated transposition. Cytochrome P-450cam expression was controlled by the Ptac-lac promoter on the broad host range vector pMMB206. Both proteins were expressed in Pseudomonas putida strain MTCC 102 (PpW). This strain does not harbor the cam plasmid, which encodes the enzymes responsible for degradation of the terpene camphor. The metabolic activity of the resulting strain (PpW-lux-cam) toward model halogenated compounds was studied. In the absence of the natural cytochrome P-450cam, electron transfer partners putidaredoxin (PR) and putidaredoxin reductase (Fp), and at low oxygen tension, the bacterial cells efficiently dehalogenate model chlorinated hydrocarbons in a light-independent reaction. Hexachloroethane and pentachloroethane were metabolized to tetrachloroethylene and trichloroethylene, respectively, at rates comparable to that of strain PpG786, which carries the scam plasmid. Reductive dehalogenation required the expression of both luciferase and cytochrome P-450 in the same cells. These results indicate that alternative electron transfer partners may be exploited for cytochrome P-450-dependent bioremediation strategies.

Camphor↗
PubMed2005

Occurrence of some organic UV filters in wastewater, in surface waters, and in fish from Swiss Lakes.

Organic UV filters are used in personal care products such as sunscreen products, and in cosmetics, beauty creams, skin lotions, lipsticks, hair sprays, hair dyes, shampoos, and so forth. The compounds enter the aquatic environmentfrom showering, wash-off, washing (laundering), and so forth via wastewater treatment plants (WWTPs) ("indirect inputs") and from recreational activities such as swimming and bathing in lakes and rivers ("direct inputs"). In this study, we investigated the occurrence of four important organic UV filter compounds (benzophenone-3, BP-3; 4-methylbenzylidene camphor, 4-MBC; ethylhexyl methoxy cinnamate, EHMC; octocrylene, OC) in wastewater, and in water and fish from various Swiss lakes, using gas chromatographic/mass spectrometric analyses. All four UV filters were present in untreated wastewater (WWTP influent) with a maximum concentration of 19 microg L(-1) for EHMC. The data indicate a seasonal variation with influent loads higher in the warmer season (June 2002) than in the colder one (April 2002). The influent loads were in the order EHMC > 4-MBC approximately BP-3 > OC. The concentrations in treated wastewater (WWTP effluent) were considerably lower, indicating substantial elimination in the plants. 4-MBC was usually the most prevalent compound (maximum concentration, 2.7 microg L(-1)), followed by BP-3, EHMC, and OC. UV filters were also detected in Swiss midland lakes and a river (Limmat) receiving inputs from WWTPs and recreational activities. However, all concentrations were low (<2-35 ng L(-1)); no UV filters (<2 ng L(-1)) were detected in a remote mountain lake. Data from passive sampling using semipermeable membrane devices (SPMDs) supported the presence of these UV filters in the lakes and the river and suggested some potential for accumulation of these compounds in biota. SPMD-derived water concentrations increased in the order Greifensee < Zürichsee < Hüttnersee. This order is reversed from that observed for methyl triclosan, used as a chemical marker for WWTP-derived lipophilic contaminants in the lakes. This indicated inputs of UV filters from sources other than WWTPs to the lakes during summer,for example,inputs from recreational activities. Fish (white fish, Coregonus sp.; roach, Rutilus rutilus; perch, Perca fluviatilis) from these lakes contained low but detectable concentrations of UV filters, in particular, 4-MBC (up to 166 ng g(-1) on a lipid basis). 4-MBC concentrations relative to methyl triclosan were lower in fish than in SPMDs exposed in the same lakes, suggesting that 4-MBC is less bioaccumulated than expected or metabolized in fish. The lipid-based bioconcentration factor (BCF(L)) estimated from the fish (roach) data and SPMD-derived water concentrations was about 1-2.3 x 10(4) and thus approximately 1 order of magnitude lower than expected from its Kow value.

Acrylates↗
PubMed2003

Epoxidation of olefins by hydroperoxo-ferric cytochrome P450.

The T252A mutant of cytochrome P450cam is unable to form the oxoferryl "active oxygen" intermediate, as judged by its inability to hydroxylate its normal substrate, camphor. In the present study, we demonstrate that T252A P450cam is nonetheless able to epoxidize olefins, due to the action of a second oxidant. However, as shown in earlier radiolytic studies and by the ability of T252A to reduce dioxygen to hydrogen peroxide, the mutant retains the ability to form the hydroperoxo-ferric reaction cycle intermediate. The present results provide strong evidence that hydroperoxo-ferric P450 can serve as a second electrophilic oxidant capable of olefin epoxidation.

Alkanes↗
PubMed2004

Oligomer-assisted synthesis of chiral polyaniline nanofibers.

We report here a novel approach to synthesize chiral PANI nanofibers in an aqueous solution. This new approach requires the following conditions: (1) Polymerization was carried out in concentrated camphor sulfonic acid solutions. (2) Aniline oligomers were used to accelerate the polymerization reaction. (3) Ammonium persulfate (oxidant) was added incrementally to the aniline solution. The high anisotropy factor of these PANI nanofibers is likely due to the "autocatalytic effect" resulting from lower oxidation potentials of aniline oligomers. Our chemical synthesis of the chiral PANI nanofibers is enantioselective and, under the optimized conditions, has an anisotropy factor (g = Deltaepsilon/epsilon) of 2.3 x 10-2.

Aniline Compounds↗