Amount Of Triton X-100 Research Articles

A new direct extraction by gas-chromatography with flame ionization detector coupled to head space method for the determination of alcohol content of high matrix wine products

Detection, identification, and quantitation of alcohol in any matrix rich medium is a common practice although sample preparation is inevitable and time consuming. A sensitive, precise and ultimately wide range method for detection, identification and quantification of main content/residual/impurity alcohols without any matrix interference that can be used for production phase quality control, pharmaceutical and/or bio-technological refinement or toxicological evaluation and for forensics is always needed. Even for quality control also for toxicological considerations, ethanol (EtOH) and very similar compound methanol has to be detected and identified definitely becomes vital. However, with the fermented products, the matrix becomes a challenging process, makes the methods inefficient or more extraction methods have to be implanted. Here we propose a new simple and reliable direct extraction method has been developed for the determination of alcohol content of high matrix wine products using the gas-chromatography with flame ionization detector coupled to head space. The method was developed with a rich and complex component mixture of fermented alcoholic beverages (wine) with very high matrix effects. Isopropanol (IPA) was preferred as an internal standard, and Triton X-100 (TX-100) was used as diluting solution in this method. The amount of TX-100, extraction temperature, and the total volume of solution in head space vial (20 mL) were optimized. 2.5% TX-100, 80 °C extraction temperature, and 2.0 ml of total volume were used as optimum condition. Stationary phase was the fused silica, Agilent J&W DB-624 column (30 m x 320 m x 1.8 m) and Helium was used as a mobile phase. GC oven temperature programme was 40C (5 min), 5C/min ramp to 60C (0 min) and 30C/min to 150C (1 min). Performance of the method was assessed by evaluating the recovery, accuracy, precision, linearity, limits of detection (LOD) and limit of quantification (LOQ). Calibration curve was drawn between the concentration of 2.5% to 15.0% EtOH (y = 1.572x – 0.702, R² = 0.9960, y; the ratio of peak area of EtOH to IPA, x: EtOH%). The slopes of standard addition and external calibration curve were statistically same. Recovery of the method was 97.5 ± 3.5 for tree different concentrations and the precision was %5.8 (n= 11). LOD and LOQ were calculated as 0.80% and 2.5%, respectively. The proposed method has a potential for application into the industry and academia with determination of the alcohol content/residual/impurity and also check the quality and content of the fermented medium without the effect of matrix.

Conversion of Electrospun Chitosan into Chitin: A Robust Strategy to Tune the Properties of 2D Biomimetic Nanofiber Scaffolds

New biomimetic micro- and nano-CsU-based fibrous scaffolds electrospun from solution containing high purity-medical grade chitosan (CsU) of fungus origin (CsU1, Mv ~174,000 and CsU2, 205,000, degree of deacetylation (DDA) ~65%) and polyethylene oxide (PEO, Mv ~ 900,000), in the presence of given amounts of Triton X-100 (from 0.01 to 0.5 wt%) as surfactant were fabricated. We demonstrate that by carefully selecting compositions and surfactant levels, porous mats with CsU content up to 90% (at this molecular weight and DDA) were achieved. Remarkable long-term stability in water or phosphate buffer solution storage were obtained by developing post-electrospinning treatment allowing the complete elimination of the PEO from the CsU-fibers as demonstrated by TGA, DSC and ESEM analysis. Subsequent reacetylation procedure was applied to convert 2D biomimetic chitosan mats to chitin (CsE)-based ones while preserving the nanofiber structure. This innovative procedure allows tuning and modifying the thermal, mechanical properties and more importantly the biodegradation abilities (fast enzymatic biodegradation in some cases and slower on the others) of the prepared nanofibrous mats. The established reproducible method offers the unique advantage to modulate the membrane properties leading to stable 2D biomimetic CsU and/or chitin (CsE) scaffolds tailor-made for specific purposes in the field of tissue engineering.

Development of Gel Phantom Having Dielectric Property Equal to Breast Tissue for Medical Metrology and the Effect of SiC Nanopowders on the Dielectric Constant

There are major shortcomings of phantoms, which are important for improving the image quality of medical devices produced by developing technology and also for calibration settings. The most important of these shortcomings is the change in the concentration of the structures forming the phantom and the deterioration of the structure due to external factors. It is important to design and develop gel phantoms which are longer time resistant to these negative effects and show electrical properties close to the living tissue. As is the case in many areas, the use of live human subjects in the medical field has not been approved and banned by many ethics committees due to the possibility of being harmful to health, and instead of living human subjects, phantoms with close features are used. In imaging systems, such as MR, Ultrasound, Tomography, X-ray, the working range of these phantoms should be determined. In addition, the use of mobile telephones has been widely used today, the absorption of electromagnetic rays emitted from these devices (SAR) as a result of the loss of the electrical property of phantom to determine the interval of distortion is important for future advances and innovations in the medical field. In the study, 5 g PVA was heated in a beaker containing 45 ml of pure water for 5 minutes at 80oC with stirring and a 10% buffer PVA solution was prepared. Different amounts of Triton X-100 were added to these buffer solutions and mixed for 15 minutes. After waiting for 24 hours, dielectric constants of gel phantoms were examined at room temperature. Agilent 85070E Network Analyzer and Performance Probe with Short Block were used to measure the dielectric constant. Gel phantoms were obtained showing the dielectric properties of human breast tissue according to the measurements taken in the frequency range 0 to 20 GHz. 10 ml 10% PVA + 5 ml Triton X-100 gel phantom from this gel phantom was examined by changing the dielectric constant by mixing 0.1 g SiC nanopowder. Afterwards, images of this gel phantom obtained with WETSEM (Wet Scanning Electron Microscope) were examined.

Synthesis and characterization of nano-sized hierarchical porous AuSAPO-34 catalyst for MTO reaction: Special insight on the influence of TX-100 as a cheap and green surfactant

Abstract Hierarchical SAPO-34 and AuSAPO-34 were synthesized as a catalyst in methanol to olefins (MTO) reaction by utilizing gold (Au) as a novel promoter and Triton X-100 (TX-100) as a cheap, non-toxic and innovative mesoporogen. In this work, independent and simultaneous effects of introducing different amounts of TX-100 and Au to the SAPO-34 framework were studied by XRD, ICP-AES, UV–vis/DRS, FESEM, HRTEM, BET, NH3-TPD, FTIR and TGA-DTA analyses. The characterization results revealed that when the concentration of TX-100 is lower than the critical micelle concentration (CMC), the effects of surfactant are only limited to the covering and steric effects and its result can only be seen on the size of SAPO-34 crystals. Nevertheless, when the concentration of the surfactant exceeds CMC, in addition to the mentioned effects, micellization of the TX-100 molecules effectively occurs and results in the formation of small SAPO-34 crystals with hierarchical porosity. The presence of a small amount of gold demonstrates a significant effect on acidic properties and coke deposition rate of the samples. Consequently, the simultaneous presence of TX-100 and Au is accompanied with a superior catalytic performance of about 97% selectivity towards light olefins and 331 min lifetime.

The role of Triton X-100 as a surfactant on the CdO nanostructures grown by the SILAR method

Abstract In this work, the effect of surfactant Triton X-100 (TX-100) on structural, morphological and optical properties of nanostructured CdO films has been researched. Four series of nanostructured CdO films with TX-100 concentrations of 0.25–1.0 M% of the growth solution were prepared by the Successive Ionic Layer Adsorption and Reaction (SILAR) technique on glass substrates and were characterized by scanning electron microscopy, surface roughness, X-Ray diffraction and UV–Vis. Spectroscopy. Scanning electron microscopy exhibited that the particle thickness increased with increasing TX-100 content. Surface roughness (Ra) measurement exhibited that Ra value accordingly decreases in the presence of TX-100. From the X-Ray diffraction patterns it was calculated that the crystallite size of the films increased parallel to the particle size with increasing TX-100 content. UV results presented that the optical bandgap values of the film can be adjusted with TX-100 content where optical bandgap decreased with increasing TX-100 content in the growth bath. The results show that the amount of TX-100 in the growth bath played a significant mission in adjusting the main physical properties of the nanostructured CdO film.

A Survey on Dispersion Mechanisms of Multi-Walled Carbon Nanotubes in an Aqueous Media by UV-Vis, Raman Spectroscopy, TGA, and FTIR

This article evaluates the dispersion of multi-walled nanotubes (MWNTs) particles in an aqueous media by ultraviolet-visible (UV-vis), Raman spectroscopy, TGA, and FTIR with using two surfactants: sodium dodecyl sulfate (SDS) and TritonX-100. UV-vis spectroscopy shows that for the same amount of Triton X-100 and SDS, Triton X-100 is able to disperse more MWNTs in aqueous media. The study of surface groups based on FTIR absorbance spectroscopy demonstrated that absorbance mechanism of surfactants on the surface of MWNTs is the interfacial interaction of –CH3 and alkyl groups when using SDS and ether groups when using Triton X-100. Presence of surface groups on MWNTs was confirmed by Raman spectroscopy and thermal gravimetric analysis.

Dispersion and stability of carbon black nanoparticles, studied by ultraviolet–visible spectroscopy

The dispersion and stability of carbon black (CB) nanoparticles in water were investigated using ultra-violet–visible (UV–vis) spectroscopy. After studying the effects of five dispersants, the most appropriate ones, Triton X-100 and N220 CB, were selected. UV–vis spectra of samples containing different amounts of Triton X-100 and a constant amount of CB were used to find the optimal circumstances of CB dispersion. Also, the stability of the dispersion was studied and it was found that the optimum conditions could be achieved in colloidal mixture containing CB and Triton X-100 in a weight ratio of 2:1. It was clarified that the mixtures containing Triton X-100 up to 50 wt% CB were stable over a period of 20 days. In order to support the UV–vis results additional techniques such as AFM, PSA and FE-SEM were employed.

Structure of the ceramide moiety of GM1 ganglioside determines its occurrence in different detergent-resistant membrane domains in HL-60 cells.

To investigate the effect of the ceramide moiety of GM1 ganglioside on its association with detergent resistant membrane domains (DRMs) in human leukemia HL-60 cells, [(3)H] labeled GM1 molecular species (GM1s) with ceramides consisting of C18 sphingosine acetylated or acylated with C(8), C(12), C(14), C(16), C(18), C(22), C(24), C(18:1), C(22:1), or C(24:1) fatty acids (FAs), or C20 sphingosine acetylated or acylated with C(8) or C(18) FA were prepared and added to culture media. GM1s uptake by HL-60 cells was affected by the structure of their ceramides. Resistance to removal with trypsin and the stoichiometry of [(125)I] cholera toxin (CT) binding indicated that the added GM1s were incorporated into the membranes of the cells used for the isolation of DRMs in a manner resembling endogenous gangliosides. The ceramide moieties of the GM1s determined their occurrence in DRMs and the dependence of their recovery in this membrane fraction on the amount of Triton X-100 (TX) used for extraction as well as on cholesterol depletion. The GM1s with sphingosine acylated with C(14), C(16), C(18) C(22), or C(24) FAs were similarly abundant in DRMs. GM1s acylated with C(18:1), C(22:1), or C(24:1) were less abundant than those acylated with saturated FA of the same length. GM1s acetylated or acylated with C(8) FA were detected in DRMs in the lowest proportion. Depletion of 73% of cell cholesterol with methyl-beta-cyclodextrin significantly affected the recovery in DRMs of GM1s acetylated or acylated with C(8) or unsaturated FAs but not of GM1 acylated with C(18), C(22), or C(24) FAs. After cross-linking with CT B subunit, all GM1s were recovered in DRMs in a similarly high proportion irrespective of their ceramide structure or cholesterol depletion. DRMs prepared with low TX concentration at the TX/cell protein ratio of 0.3:1 were separated by multistep sucrose density gradient centrifugation into two fractions. The GM1s with sphingosine acetylated or acylated with C(18) or C(18:1) FAs occurred in these fractions in different proportions.

Effect of Salt on Temperature-Swing Adsorption of Nonionic Surfactant with Poly(Vinylmethyl Ether) Gel.

The effect of salt concentration on temperature-swing adsorption of nonionic surfactant Triton X-100 with poly(vinylmethylether) gel (PVMEG) was investigated with sodium salts of citrate, succinate, sulfate, hydrogen phosphate, chloride and nitrate. With increasing salt concentration, the amount of Triton X-100 adsorbed on PVMEG increased and the critical temperature range across which the adsorbed amount of Triton X-100 drastically changed shifted to the lower temperature side. The effects of salt type and concentration on temperature-swing adsorption process were evaluated in terms of effective adsorbed amount, midpoint temperature and temperature sensitivity. The effective adsorbed amount increased with increasing ionic strength up to a certain critical value depending on salt type, and then sharply decreased above the critical value. The dependency of midpoint temperature on ionic strength below the critical value was different from that above the critical value. The temperature sensitivity became minimum at ionic strength around the critical value .The critical ionic strength was found to be depend mainly on the valence of ion.

STUDY OF THE METHOD OF COMPLEXATION-SUPERCRITICAL FLUID EXTRACTION OF COPPER IONS WITH 8-HYDROXYQUINOLINE

8-Hydroxyquinoline, methanol, and Triton X-100 were first used together in the extraction of metal ions by supercritical fluid. In the new system, the effects of pressure, temperature, and the volume of supercritical CO2 used on the efficiency of supercritical fluid extraction (SFE) were systematically investigated. The recovery of Cu2+ was only 17.7% by pure supercritical CO2 while the recovery increased significantly (83.6%, RSD=3.64%, n=5) with the addition of a suitable amount of methanol (v/v=5%). In order to further enhance the recovery, a suitable amount of Triton X-100 was added to the samples, and the results were favorable (96.6%, RSD=2.76%, n=5).

ATP synthesis by the F0F1 ATP synthase from thermophilic Bacillus PS3 reconstituted into liposomes with bacteriorhodopsin. 1. Factors defining the optimal reconstitution of ATP synthases with bacteriorhodopsin.

Optimal conditions for the reconstitution of bacteriorhodopsin and H+-transporting ATP synthase from thermophilic Bacillus PS3 (TF0F1) were determined. Phosphatidylcholine/phosphatidic acid liposomes prepared by reverse-phase evaporation were treated with various amounts of Triton X-100, octyl glucoside, octaethylene glycol n-dodecylether, sodium cholate or sodium deoxycholate and the incorporation of proteins by these detergents was studied at each step of the solubilization process. After removal of detergent by means of SM-2 Bio-Beads, the light-driven ATP synthase activities of the resulting proteoliposomes were analyzed at 40 degrees C. The nature of the detergent used for reconstitution was important for determining the mechanism of protein insertions. The most efficient reconstitutions were obtained with octyl glucoside or Triton X-100 by insertion of the proteins into detergent-saturated liposomes. The conditions for reconstitutions were further optimized with regard to functional coupling between bacteriorhodopsin and TF0F1. It was demonstrated that one of the main factors limiting the production of efficient reconstituted proteoliposomes was related to activation of the highly stable TFO-F1. Activation was accomplished by total solubilization of phospholipids and proteins in a Triton X-100/octyl glucoside mixture containing 20 mM octyl glucoside, leading to a threefold stimulation of the ATP synthase activity. Final ATP synthase activities depended greatly on the lipid/bacteriorhodopsin and the lipid/TF0F1 ratios as well as on the phospholipid used. In particular, light-driven ATP synthesis depended upon the presence of negatively charged phospholipids. Cholesterol was found to induce a fourfold increase in ATP synthase activity with a concomitant 65% decrease in the Km for ADP, suggesting that sterols can modulate catalytic events mediated by F1. Preparations obtained by this step-by-step reconstitution procedure displayed activities up to 20-fold higher (500-800 nmol ATP x min(-1) x mg TF0F1(-1) in the presence of cholesterol) than the maximal values reported in the literature for light-driven ATP synthesis TF0F1 measured under similar conditions. This study also allowed rationalization of the different parameters involved in reconstitution experiments and the present simple method is shown to be of general use for preparation of efficient proteoliposomes containing bacteriorhodopsin and choloroplast or mitochondrial F0F1-type ATP synthases.

Phase Behavior of Tyloxapol/Triton X100/Water Mixtures

The influence of admixture of Triton X100 to the polymer tyloxapol and the phase behavior of the mixtures in contact with water was investigated by viscometry, polarization microscopy, and X‐ray scattering. The viscosity of tyloxapol/Triton X100 mixtures is lower than that of pure tyloxapol. With increasing Triton X100 content, the phase behavior of the surfactant mixtures in contact with water evolves from the complex behavior of tyloxapol to the simpler one of Triton X100. In contact with water, mixtures rich in tyloxapol form hexagonal, cubic, and lamellar lyotropic liquid crystalline phases over a wide range of concentration and temperature, whereas Triton X100/water mixtures form only a hexagonal phase in a limited concentration and temperature range. The polymeric nature of tyloxapol stabilizes the liquid crystalline structures, and the size of the supramolecular structures in the water‐containing surfactant systems is independent of the tyloxapol/Triton X100 mixing ratio but depends highly on water content. The ability of tyloxapol to form stable lyotropic liquid crystalline phases at body temperature, which has been proposed as a basis for the development of novel peroral sustained‐release systems, is not significantly impaired by the addition of appropriate amounts of Triton X100. Admixture of Triton X100 to tyloxapol may thus provide a way to circumvent processing problems during the preparation of pharmaceutical formulations based on the highly viscous tyloxapol.

Reconstitution of the sarcoplasmic reticulum Ca 2+-ATPase: mechanisms of membrane protein insertion into liposomes during reconstitution procedures involving the use of detergents

The Ca 2+-ATPase from skeletal muscle sarcoplasmic reticulum was reconstituted into scaled phospholipid vesicles using the method recently developed for bacteriorhodopsin (Rigaud, J.L., Paternostre, M.T. and Bluzat, A. (1988) Biochemistry 27, 2677–2688). Liposomes prepared by reverse-phase evaporation were treated with various amounts of Triton X-100, octyl glucoside, sodium cholate or dodecyl octa(oxyethylene) glycol ether (C 12E 8) and protein incorporation was studied at each step of the liposome solubilization process by each of these detergents. After detergent removal by SM-2 Bio-Beads the resulting vesicles were analyzed with respect to protein incorporation by freeze-fracture electron microscopy, sucrose density gradients and Ca 2+ pumping measurements. The nature of the detergent used for reconstitution proved to be important for determining the mechanism of protein insertion. With octyl glucoside, direct incorporation of Ca 2+-ATPase into preformed liposomes destabilized by saturating levels of this detergent was observed and gave proteoliposomes homogeneous in regard to protein distribution. With the other detergents, optimal Ca 2+-ATPase pumping activities were obtained when starting from Ca 2+-ATPase/detergent/phospholipid micellar solutions. However, the homogeneity of the resulting recombinants was shown to be dependent upon the detergent used and in the presence of Triton X-100 or C 12E 8 different populations were clearly evidenced. It was further demonstrated that the rate of detergent removal drastically influenced the composition of resulting proteoliposomes; upon slow detergent removalfrom samples solubilized with Triton X-100 or C 12E 8 different populations were clearly evidenced. seggregated and/or aggregated in very few liposomes while upon rapid detergent removal compositionally homogeneous proteoliposomes were obtained with high Ca 2+ pumping activities. The reconstitution process was further analyzed by centrifugation experiments and the results demonstrated that the different mechanisms of reconstitution were driven predominantly by the tendency for self-aggregation of the Ca 2+-ATPase. A model for Ca 2+-ATPase reconstitution was proposed which accounted for all our results. In summary, the advantage of the systematic studies reported in this paper was to allow a rapid and easy determination of the experimental conditions for optimal detergent-mediated reconstitution of Ca 2+-ATPase. Proteoliposomes prepared by the present simple method exhibited the highest Ca 2+ pumping activities reported to date in Ca 2+-ATPase reconstitution experiments performed in the absence of Ca 2+ precipitating agents.

Reconstitution of CF0F1 into liposomes using a new reconstitution procedure

The H(+)-ATPase (ATP synthase) from chloroplasts was isolated, purified and reconstituted into phosphatidylcholine/phosphatidic-acid liposomes. Liposomes prepared by reverse-phase evaporation were treated with various amounts of Triton X-100 and protein incorporation was studied at each step of the solubilization process. After detergent removal by SM2-Biobeads, the activities of the resulting proteoliposomes were measured indicating that the most efficient reconstitution was obtained by insertion of the protein into preformed, detergent-saturated liposomes. The conditions for the reconstitution were optimized with regard to ATP synthesis driven by an artificially generated delta pH/delta psi. An important benefit of the new reconstituted CF0F1 liposomes is the finding that the rate of ATP synthesis remains constant up to 10 s, indicating a low basal membrane permeability.

Surface Properties of Coal Fines in Water. I. Electrokinetics and Surfactant Adsorption”“

The adsorption of phenol, p-nitrophenol, the nonionic surfactant Triton X-100 (a commercial mixture of octylphenol poly ethoxylates) and the cationic surfactant dodecyltrimethylammonium bromide (DTAB) from aqueous solution on coal fines from a coal washing plant has been studied. Adsorbate solution concentrations range from 0-8 × 10-4 m. For the cationic and nonionic surfactants both adsorption isotherms and electrokinetic isotherms were determined. The adsorption of phenol, but not of Triton X-100 and DTAB, is found to increase with time for periods up to 300 h. For short contact times (< 30 h), the amount of Triton X-100 adsorbed is about three times higher than the amount of phenol adsorbed at the same solution concentration. The electrokinetic data show that the zeta potential of the coal is not affected by the adsorption of Triton X-100. On the other hand, adsorption of the cationic surfactant strongly influences the zeta potential. For negatively charged coal, i.e., at higher solution pH (iep of the...

Action of a microbial glycerophospholipid:cholesterol acyltransferase on plasma from normal and LCAT-deficient subjects.

The action of a bacterial acyltransferase similar in overall reaction mechanism to the plasma enzyme lecithin:cholesterol acyltransferase (LCAT) has been studied using normal plasma and lipoproteins and plasma from LCAT-deficient patients. The microbial enzyme (GCAT) catalyzed acyl transfer using phosphatidylcholine and cholesterol in all of the lipoprotein fractions, presumably because it has no apolipoprotein cofactor. In addition, the enzyme was capable of hydrolyzing cholesteryl ester in lipoproteins but not in small unilamellar vesicles nor in micellar dispersions containing low amounts of Triton X-100. This suggests that cholesteryl ester is exposed on the surface of lipoprotein particles or that it may be transferred there quickly from the interior. Although considerable interconversion of radiolabeled cholesterol and cholesteryl ester could be demonstrated upon treatment of normal plasma or lipoproteins with the enzyme, there was little change in the actual amount of either steroid. This indicates that the rate of cholesteryl ester formation is very similar to the rate of hydrolysis. The relative proportions of cholesterol and cholesteryl ester in normal plasma are therefore near the equilibrium ratio for the reaction carried out by GCAT, or the ratio is controlled by the properties of the lipoproteins themselves. During reaction with the microbial acyltransferase, the ratio of cholesterol to cholesteryl ester in plasma from LCAT-deficient patients was reduced substantially, suggesting that the enzyme may have some practical applications.

A procedure for the complete clarification of milk of various species and its suitability for use with colorimetric measurements

SummaryBovine, caprine, ovine and human milks have been clarified by addition of Triton X-100 and EDTA followed by a short incubation. Generally, addition of 4·2% Triton X–100 and 5·4% EDTA was sufficient and with skim-milk samples no dilution was necessary. With whole milks some dilution and greater amounts of Triton X-100 or longer incubation times or higher temperatures were required. These factors were interrelated to some extent and the optimum conditions will be determined by convenience and any particular requirements of the experiment. The attainment of optically transparent milk samples greatly facilitates colorimetric measurements; as examples we have shown that total protein may be estimated by the biuret reaction, NH2groups measured with 2,4,6-trinitrobenzene sulphonic acid and SH groups by reaction with 5, 5′-dithiobis(2-nitrobenzoic acid). Acid phosphatase activity in bovine milk was followed colorimetrically by reaction withp-nitrophenyl phosphate to demonstrate the suitability of the clarification procedure in the measurement of enzymic reactions.

Purification of cytochrome b-561 : An integral heme protein of the adrenal chromaffin granule membrane

1. 1. Cytochrome b-561, an integral heme protein of the adrenal chromaffin granule membrane, has been solubilized and isolated in highly purified and water soluble form by an non-ionic detergent procedure. 2. 2. The prosthetic group of cytochrome b-561 is protoheme IX. 3. 3. Gel electrophoresis in sodium dodecylsulfate of the isolated cytochrome revealed a single band of a low molecular weight polypeptide, and on the basis of amino acid analyses, a minimum molecular weight of 4380 was computed for the apoprotein. 4. 4. The cytochrome is a typical integral membrane protein with a high percentage of hydrophobic amino acids (i.e. 36%) and a high average hydrophobicity (i.e. 1173 cal/residue). A considerable amount of Triton X-100, firmly bound to the apoprotein, is responsible for its solubility in aqueous solution. 5. 5. Molecular-sieve chromatography indicated that the cytochrome exists in an aggregated form in aqueous solution. 6. 6. The absorption spectra revealed peaks at 360, 415 and 531 nm in the oxidized form, and at 427, 530 and 561 nm in the reduced form. The millimolar absorptivity (ε) at the α-band (reduced) was 28.3 mM −1·cm −1 at 561 nm.