bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relaxivity Study and X‐ray Structure of Gd(III)‐diethylenetriamine‐N,N′,N′‐triacetic‐N,N″‐bis(benzylamide). A Potential MRI Contrast Agent
Authors: Wang Yun‐Ming , Cheng Tsann‐Hwang , Sheu Reu‐Sheng , Chen I‐Ting , Chiang Michael Y. 
Published: May 2015

AbstractThe new bis(amide) derivatives of DTPA (diethylenetriamine‐N,N,N′,N″,N″‐pentaacetic acid), diethylenetriamine‐N,N′,N″‐triacetic‐N,N″‐bis(benzylamide) (DTPA‐BBA) have been synthesized. The crystal structure of gadolinium(III) complex of DTPA‐BBA ([Gd(DTPA‐BBA)]) has been determined by X‐ray crystallography: C28H52GdN5O17, Mw = 889 g mol−1, space group \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm P}\bar 1 $\end{document} (#2) (triclinic), a = 12.645(4), b=14.125(8), c = 12.623(4) Å, α = 111.60(3), β = 114.79(3), γ = 88.39(4)°, V = 1881(1) Å3, Z = 2, Dx = 1.569 g/cm3, λ(Mo Kα) =0.71069 Å, μ = 18.44 cm−1, final R = 0.047, Rw = 0.046 for 3755 independent observed reflections at 23 °C. The coordination sphere of Gd(III) comprises three amine nitrogens, two amide oxygens, three carboxylic acid oxygens, and one water. The relaxivity of Gd(III) complex was determined to be R1 = 4.08(4) and R2 = 6.06(5) dm3 mmol−1 s−1 at pH = 7.0, 20 MHz, and 37(1) °C. Additionally, the R1 relaxivity for Gd(III) chelate was found to be invariant with respect to pH changes over the range of 2‐10. This indicates that a constant inner‐sphere hydration number is associated with the [Gd(DTPA‐BBA)] complex. Hence the high stability of the complex is demonstrated.
Platelet Aggregation Inhibitor from Ganoderma lucidum
Authors: Wu Tian‐Shung , Shi Li‐Shian , Kuo Sheng‐Chu , Cherng Ching‐Yuh , Tung Shu‐Fang , Teng Che‐Ming 
Published: May 2015

AbstractLucidenic acid A (1) and a new lactone, lucidenolactone (2) were isolated from the fruiting bodies of Ganoderma lucidum. Their structures were elucidated by spectroscopic method and single‐crystal X‐ray analysis. Lucidenolactone (2) showed significant antiplatelet aggregation activity. The NMR spectral data of lucidenic acid A were also reassigned.
Preparation of Aluminum Alkoxides and Crystal Structures of [Al{(S)‐(‐)‐μ‐OC(H)(CH3)C(Ph)2OH}Cl2]2·2Et2O and [(μ‐O(CH2)2OPh)AlMe2]2
Authors: Ko Bao‐Tsan , Lee Ming‐Der , Lin Chu‐Chieh 
Published: May 2015

AbstractThe reaction of (S)‐(‐)‐1, l‐diphenyl‐propane‐1,2‐diol with AlCl3 in diethyl ether furnishes the product [Al((S)‐(‐)‐μ2‐OC(H)(Me)C(Ph)2OH)Cl2]2 1, which decomposes slowly above 25 °C. Complex 1·2Et2O Crystallizes in the non‐centrosymmetric monoclinic space group P21 with a=10.591(1) Å, b=16.718(1) Å, c = 12.156(2) Å, β=99.30(2)°, V = 2124.1(3) Å3, z = 4, R = 4.67%, Rw=4.84%, GoF=1.14. The structure of 1 shows a dimer feature, which is hydrogen bonded to two diethyl ether molecules. In the reaction of 2‐phenoxyethanol with AlMe3, the dimeric [(μ‐O(CH2)2OPh)AlMe2]2 is obtained in high yield. 2 crystallizes in the monoclinic space group P21/c with a = 7.398(2) Å, b = 7.376(2) Å, c = 20.710(2) Å, β = 90.56(2)°, v = 1129.9(4) Å3, z=4, R=5.70%, Rw=7.15%, GoF=1.59.
The Studies of Microwave Effects on the Chemical Reactions
Authors: Chen Shui‐Tein , Tseng Ping‐Hui , Yu Hui‐Ming , Wu Chi‐Yue , Hsiao Kwo‐Feng , Wu Shih‐Hsiung , Wang Kung‐Tsung 
Published: May 2015

AbstractMicrowave heating involves direct absorption of energy by functional groups that bear ionic conductivity or a dipole rotational‐effect, and this energy is then released into the surrounding solution. This absorption of energy causes the functional groups involved to have higher reactivity to other surrounding reactants than when they are simply incubated with the reactants at the same temperature. In other word the enhanced rate of the reaction can be due to the reactant stirred by the molecular dipole rotation and molecules themselves acting as a stirring bar. In contrast to conventional heating, the salient feature of “dipole rotation” constitutes one efficient form of “molecular agitation” or “molecular stirring” many aspects of which can be explore in chemical reactions. We will discuss some of the useful applications of this “molecular agitation” by means of microwave irradiation. Using this unique technology, we have developed: 1) a method to control the cleavage sites of peptide bonds, especially those bonds connected to aspartic acid residues inside the native peptides and proteins, 2) a method to increase coupling efficiency in solid‐phase peptide synthesis using a common microwave oven, 3) a novel procedure that increases the rate of alcalase‐catalyzed reactions using microwave irradiation in peptide‐bond formation with proline as a nucleophile and selective benzoylation of a pyranoside derivative, 4) a procedure to solubilize and hydrolyze retrograded starch, 5) a novel procedure to enhance the rate of saponification in a serum sample for very long chain fatty acid analysis.
Effect of A Magnetic Field on Photophysical Processes of Molecules
Authors: Lin S. H. , Hayashi M. , Kono H. , Hayashi H. , Abe H. , Ikeda S. 
Published: May 2015

AbstractA main purpose of this paper is to present a density matrix treatment of the magnetic quenching of molecular luminescence. Unlike the previous theories, which only consider the magnetic effect on the nonradiative rate constant, the present theory describes the time‐evolution of the system under the action of a magnetic field. Our theory can treat both the steady state and transient molecular luminescence affected by a magnetic field.
The Resolution of Enantiomeric Ibuprofen on Chiral Stationary Phases Containing N‐Arylcarbamoyl Derivatives of Phenylglycine
Authors: Lin Jer‐Yann , Yang Mei‐Hui 
Published: May 2015

AbstractA series of fourteen anilide derivatives of ibuprofen were resolved on six chiral stationary phases (CSPs) derived from N‐arylcarbamoyl derivatives of (S)‐phenylglycine. Excellent chiral resolutions were achieved on these CSPs. The ionic‐type CSPs showed better chiral recognition abilities than the corresponding covalent‐type CSPs, and the CSP bearing two chiral centers has better performance than the CSPs bearing only one chiral center. The highest separation factor was achieved using the ionic‐type CSP bearing two chiral centers for the resolution of the 3,5‐dinitroanilide derivative of ibuprofen. This result is better than those reported in literature for the resolution of ibuprofen on the CSPs derived from amino acids, According to the chromatographic behaviors, the hydrogen bonding interaction, the π‐π interactions provided by the phenyl groups in CSPs bearing one chiral center, and the phenylethylcarbamoyl moiety in CSPs bearing two chiral centers dominate the chiral recognition.
Preconcentration and Determination of Copper(II) at a Chemically Modified Electrode Containing Salicylaldehyde Thiosemicarbazone
Authors: Chang Chin‐Hung , Liu Chuen‐Ying 
Published: May 2015

AbstractA chemically modified electrode (CME) containing salicylaldehyde thiosemicarbazone (TSCsal) was evaluated for the ability to preconcentrate copper(II) prior to quantification by voltammetry. The CME has been used for the very sensitive and selective analysis of trace amounts of copper(II). A detection limit of 0.1 ppb was obtained by applying anodic stripping voltammetry with a flow system. The parameters that affect the sensitivity and possible interference by other ions or chelating agents have been examined in detail. The CME exhibits high stability and the response could be reproduced for four preconcentration‐determination‐renewal cycles [10ppbCu(II)] with a 2.87% relative standard deviation. The proposed method has been applied to the determination of copper(II) in tap water, drinking water, and NASS‐3 standard reference sea water samples. The results gave satisfactory recoveries.
15N NMR Study of Coordinated Amine, Aminocarbyne, and Carboxamido Groups in Triosmium Clusters
Authors: Chen Chun‐Ting , Chen Chi‐Cheng , Lin Su‐Ching , Hong Fung‐E , Lin Ying‐Chih , Lu Kuang‐Lien 
Published: May 2015

AbstractThe 15N NMR spectra of the complexes Os3(CO)10(μ2‐CONHPri)(μ2‐CNHR) (1a, R = Pr; 1b, R = CH2Ph) and Os3(CO)9(NH2Pri)(μ2‐CONHPri)(μ2‐CNHR) (2a, R = Pr; 2b, R = CH2Ph) are studied by using the 1H detected (inverse) 1H‐15N correlated spectroscopy. The 15N chemical shifts and the 1H‐15N coupling constants fall in characteristic regions for each of the coordinated amine, aminocarbyne, and carboxamido ligands and these values are related to their bonding types. The NMR data are discussed in terms of the influence of the paramagnetic term which is the major factor determining the chemical shifts. A comparison is made to understand the 15N chemical‐shift differences between the coordinated nitrogen‐containing ligands and the corresponding free organic molecules.
Reinvestigation of the Reaction of Sodium Borohydrate with Benzhydryl Halides under Solvolytic Conditions
Authors: Liu Kwang‐Ting , Huang Huei‐Chin 
Published: May 2015

AbstractSolvolysis of benzhydryl halides in aqueous diglyme containing sodium borohydride was studied. Contrary to the literature, sodium borohydride was found not to be a convenient trap for benzhydryl carbocations, especially for those containing electron‐withdrawing substituent, and it decomposed appreciably in 80% aqueous diglyme at 45 °C. In addition, significant acceleration of reactions due to the presence of sodium borohydride was realized in the solvolysis of 3‐chloro‐ and 3‐trifluoromethyl‐benzhydryl chlorides.
Synthesis, Reactions, and Structure of 5‐Cyano‐4‐ethoxy‐1‐ethoxycarbonyl‐2‐methylazuleno[1,8‐b,c]pyran
Authors: Wu Chi‐Phi , Cheng Ling‐Yu , Wen Yuh‐Sheng , Hsiao Chwan‐Deng 
Published: May 2015

AbstractBicyclic azulene compounds, ethyl 4‐(cyanoethoxycarbonylmethyl)‐2‐methylazulene‐1‐carboxylate (2) and ethyl 4‐(cyanoethoxycarbonylmethyl)azulene‐1‐carboxylate (3) were prepared from ethyl 4‐chloro‐2‐methylazulene‐1‐carboxylate (7) and ethyl 4‐ethoxyazulene‐1‐carboxylate (8), respectively. Oxidation of 2 with DDQ gave the title compound, 5‐cyano‐4‐ethoxy‐1‐ethoxycarbonyl‐2‐methylazuleno[1,8‐b,c]pyran (1) and a minor compound, ethyl 4‐cyanomethyl‐2‐methylazulene‐1‐carboxylate (9). Oxidation of 3 by DDQ produced only ethyl 4‐cyanomethylazulene‐1‐carboxylate (10), Reaction of 1 with 100% H3PO4 at room temperature and 100 °C gave 5‐cyano‐4‐ethoxy‐2‐methylazuleno[1,8‐b,c]pyran (11) and 2‐methyl‐4,5‐dihydrozuleno[1,8‐b,c]pyran‐4‐one (12), respectively. All the new compounds were characterized by IR, UV‐vis, NMR and Mass spectra, and the structure of 1 was determined by X‐ray crystallography. Crystal data for 1; space group P21/n, a = 7.391(1), b = 9.660(5), c = 22.859(1) Å, B = 97.01(1)°, V = 1620.0(3) Å3, Z = 4, with final residuals R = 0.047 and Rw = 0.055.
The Constituents from the Stems of Annona cherimola
Authors: Chen Chung‐Yi , Chang Fang‐Rong , Wu Yang‐Chang 
Published: May 2015

AbstractThirty‐five compounds including twenty‐one alkaloids, lysicamine (1), liriodenine (2), atherospermidine (3), oxoxylopine (4), oxoanolobine (5), oxoglaucine (6), (‐)‐anonaine (7), (‐)‐asimilobine (8), (‐)‐xylopine (9), (‐)‐anolobine (10), (‐)‐norisocorydine (11), (+)‐laurotetanine (12), (+)‐isocorydine (13), (‐)‐N‐methylasimilobine (14), (+)‐N‐methyllaurotetanine (15), (‐)‐norushinsunine (16), (‐)‐ushinsunine (17), (‐)‐N‐formylanonaine (18), (+)‐stepharine (19), (+)‐orentaline (20), and (‐)‐kikemanine (21); four kauranes, ent‐kaur‐16‐en‐19‐oic acid (22), 16β‐hydroxy‐17‐acetoxy‐ent‐kauran‐19‐al (23), 17‐acetoxy‐16β‐ent‐kauran‐19‐oic acid (24), and 16β‐hydroxy‐17‐acetoxy‐ent‐kauran‐19‐oic acid (25); two amides, N‐trans‐femloyltyramine (26), and N‐trans‐caffeoyltyramine (27); one purine, adenosine (28); one lactam amide, squamolone (29); and six steroids, β‐sitosterol (30), stigmasterol (31), β‐sitostenone (32), stigmasta‐4,22‐dien‐3‐one (33), 6β‐hydroxy‐β‐sitosterone (34), and 6β‐hydroxystigmasterone (35) are isolated from the stems of Annona cherimola. These compounds were characterized and identified by physical and spectral evidence. Among them, (‐)‐norisocorydine (11) was elucidated as a new enantiomer with a levorotary configuration, which is isolated for the first time.
Base‐Catalyzed Keto‐Enol Tautomerism of Diazepam
Authors: Yang Shen K. 
Published: May 2015

AbstractThe hydrogens at 3‐position of diazepam, a frequently prescribed anxiolytic drug worldwide, undergo an efficient exchange with deuterium atoms in alkaline deuterated methanol. The position of deuterium exchange is confirmed by proton nuclear magnetic resonance and mass spectral analyses. A base‐catalyzed keto‐enol tautomerism is proposed to be responsible for the observed deuterium exchange. This finding has been applied to the preparation of tritium‐labeled diazepam in which only aromatic protons are labeled with tritium atoms. A tritium‐labeled diazepam lacking tritium atoms at 1 and 3 positions is valuable as a substrate for quantitative metabolism studies.
Denaturation of Adenosine Deaminase with Urea and Guanidine Hydrochloride
Authors: Moghaddamnia M. H. , Saboury A. A. , Hakimelahi G. H. , Moosavi‐Moovahedi A. A. 
Published: May 2015

AbstractThe denaturation effect of urea and guanidine hydrochloride on (lie adenosine deaminase has been investigated spectrophotometrically at the two temperatures of 27 °C and 37 °C at pH = 7.50, phosphate buffer (55 mM). A simple, reversible two stale transition, N ⇔︁ D, was used to analyze the denaturation process from which conformational stability was estimated using three different methods, namely, the linear extrapolation method (LEM), Tanford's model (TM), and the denaturant binding method (DBM). A good agreement was observed among these methods. The results from free energy of denaturation at zero concentration of denaturant, ΔG°H2O, show the fragile conformation for adenosine deaminase molecule.
Electrochemical Characterizations of NaY Zeolite‐Entrapped Copper Dicyanoanthraquinone Diimines
Authors: Chang Jun‐Shang , Liu Lilian‐Kao , Wang Chong‐Mou 
Published: May 2015

AbstractIntrazeolite copper dicyanoanthraquinone diimines (NaY/Cu(DCNAQI) were synthesized within NaY zeolite using a “ship‐in‐a‐bottle” technique. These particles were subjected to CV and EIS characterizations based on their associated particulate electrodes. Analysis of the EIS over a wide range of frequency and at potentials around the formal potential of DCNAQI0/− showed that the charge transfer resistance and the double layer capacitance in the equivalent circuit based on the Fletcher transmission lines were sensitive to the probing potential and the concentration of the free DCNAQI coexisting in the electrolyte solutions. Although CV does not provide much information about the influence of hydrogen on NaY/Cu(DCNAQI), the EIS characterizations suggested hydrogen can significantly accelerate the charge transfer kinetics for most NaY/Cu(DCNAQI) particles.
The Generalized Parameterization Procedure for Semiempirical MO Method and Calculation of ionization Potentials for the Fourth‐Period Element Molecules
Authors: Lu Li‐Hwa , Chen Cheng , Sun Kuang‐Chung 
Published: May 2015

AbstractThis study presents a set of the generalized parameters from a unique resource for the elements which are from the first‐period to the fourth‐period (H to Xe). In addition, these series of parameters are used to examine forty‐five compounds consisting of the fourth‐period elements and the second‐period transition metal elements. Herein, the major calculation theory applied is the s‐p‐d INDO MO method.To verify the reliability of the molecular calculations, similar calculations of the STO‐3G and STO‐3G* ab inito methods, along with the semiempirical PM3 and AM1 methods are also compared. Results in this study demonstrate that the s‐p‐d INDO MO computed with the generalized parameter is the best available method.
Theoretical Studies of Proton Transfer Reactions—Energy Barriers and the Marcus Equation
Authors: Chu Chih‐Hung , Ho Jia‐Jen 
Published: May 2015

AbstractThe reactants, ion‐dipole complexes, transition states, and products for the proton transfer reactions HBCOH+ + OCXH → HBCO + +HOCXH optimized at the SCF/4–31G* level of theory for B, X = F, Cl, H, CH3, CH2Cl, CHCl2 and CCl3 are studied. The intrinsic barrier ΔE*BX correlates with the degree of the O‐O bond contraction in the transition structure. Both intrinsic and overall barriers can be predicted with the aid of Marcus theory. Progressive degrees of chlorination of the alkyl group in B produce decreases in the barrier to proton transfer from HBCOH+ to OCXH and increases in the reverse transfer barriers. These changes can be quantitatively reproduced by the Marcus equation for all systems.
Regio‐ and Stereocontrolled Nucleophilic Addition Reactions of An Unsymmetrically Disbustituted Butadiene η4‐Molybdenum Cationic Complex
Authors: Chou Shang‐Shing P. , Sheng Hui‐Tuo 
Published: May 2015

AbstractThe reactions of a new cationic complex, [Cp(CO)2Mo(η4‐2‐methyl‐3‐SPh‐C4H4)]+ PF−6 (3), with carbon, hydride, and nitrogen nucleophiles were found to give only the C‐1 addition products in good yield. The X‐ray crystal structures of two of the addition products 4a and 4e confirm the regio‐ and stereochemistry of the nucleophilic additions.
Ene Reaction of Pummerer‐Type Reaction Intermediate and Synthesis of Achillea Amide
Authors: Lee Huey‐Jy , Wang Huey‐Min , Chen Ling‐Ching 
Published: May 2015

AbstractPummerer‐type reaction intermediate 2 of methyl α‐(methylthio)acetate (1) has been found to react with 1‐alkenes to afford ene adducts 3. Achillea amide 5 was synthesized from the adduct 3g.
Formation Mechanism of Polyaniline: Evidence from the Post‐Reactions of Isolated Intermediates
Authors: Chiou Yeong‐Han , Wu Chun‐Guey 
Published: May 2015

AbstractThe formation mechanism of Polyaniline was derived from the post reactions of the polymerization intermediate. The intermediate, RPAN, (3000 Å thickness film, purplish‐blue in color) was isolated on silane modified substrates after polymerization for 10 minutes. Under air, RPAN converts to emeraldine salt within a couple of seconds. In the inert atmosphere, the conversion occurred at a relatively low speed. In acidic media, the intermediate was believed to be a very reactive radical cation, which oxidized then coupled with aniline oligomers to start the auto‐catalytic chain growing process. When the radical cation was quenched in water or acid, a violet species, IPAN, with a structure composed mostly of pernigraniline units, was formed. IPAN reacts slowly with aniline oligomers in the presence of protons and oxidants to emeraldine. The conversion processes were monitored by IR and Uv/Vis/NIR spectroscopy.
Electron Impact Mass Spectra of Some Arylpyridines
Authors: Lin Shaw‐Tao , Yang Fu‐May , Liang David , Shiao Min‐Jen 
Published: May 2015

AbstractThe mass spectra of 56 arylpyridines were studied under EI conditions. The fragmentations of this series of compounds are relatively simple because of a stable skeleton containing two aromatic rings. The orientations of cleavage of the methoxyl and methoxycarbonyl groups strongly depend on their position on the pyridine ring and can be applied to the differentiation of the isomers.
Chemical Constituents of Neolitsea parvigemma and Neolitsea konishii
Authors: Chen Keh‐Shaw , Chang Fang‐Rong , Chia Yi‐Chen , Wu Tian‐Shung , Wu Yang‐Chang 
Published: May 2015

AbstractTwenty‐four compounds including three flavonoids, kaempferol‐3‐O‐rhamnoside (1), quercetin‐3‐O‐rhamnoside (2), and taxifolin‐3‐O‐rhamnoside (3); three ferulates, docosanylferulate (4), tetracosanylferulate (5), and hexacosanylferulate (6); two cyclohex‐2‐en‐1‐ones, blumenol A (7), and roseoside (8); two sesquiterpenes, zeylanidine (9), and zeylanicine (10); four triterpenes, lupeol (11), lupenone (12), taraxerol (13), and taraxerone (14); one steroid, β‐sitosterol (15); one amide, N‐trans‐feruloylmethoxytyramine (16); eight alkaloids, roemerine (17), actinodaphnine (18), N‐methylactinodaphnine (19), glaucine (20), and oxoglaucine (21), boldine (22), corydine (23) and methoxyannomontine (24) were isolated from Neolitsea parvigemma and N. konishii. These compounds were characterized and identified by physical and spectral evidence. Among them, compounds 1, 2, 3, 4, 5, 6, 7, 8, 13, 14, 16, 20, 21, 23, and 24, were isolated for the first time from this genus. This finding is useful as a basis for chemotaxonomy.
Electrocatalytic Oxidation of Amines to Nitriles on a TEMPO‐modified Graphite Felt Electrode (TEMPO = 2,2,6,6‐tetramethylpiperidin‐1‐yloxyl)
Authors: Kashiwagi Yoshitomo , Kurashima Futoshi , Kikuchi Chikara , Anzai Jun‐Ichi , Osa Tetsuo , Bobbin James M. 
Published: May 2015

AbstractPreparative electrocatalytic oxidation of amines to nitriles was successfully achieved on a poly (acrylic acid)‐coated graphite felt electrode immobilizing 4‐ammo‐2,2,6,6‐tetramethylpiperidin‐1‐yloxyl in high selectivity (> 95%) and high current efficiency (> 92%).
Intramolecular Cycloaddition of Nitrones and Nitrile Oxides with Sulfur‐Substituted Dienes and Its Synthetic Applications
Authors: Chou Shang‐Shing P. , Yu Yu‐Ju 
Published: May 2015

AbstractA series of sulfur‐substituted dienyl nitrones and oximes were conveniently prepared from the 3‐sulfolene precursors. Regiospecific intramolecular 1,3‐dipolar cycloadditions of nitrones and nitrile oxides with sulfur‐substituted dienes have been efficiently carried out from the suitable 3‐sulfolene precursors. The stereochemistry of the cycloaddition of nitrones depends on the structure of the substituent (sulfide or sulfone) on the diene as well as on the chain length connecting the diene and nitrone. The fused bicyclic products obtained from these reactions have been converted to some interesting heterocyclic compounds which have the useful structure of vinyl sulfide or sulfone.
Laser Desorption Ionization of Melamine and Identification of Fragmentation Channels from Ion Velocity Distribution Measurements
Authors: Han Chau‐Chung , Wang Ru‐Wen , Lee Tieh‐Sheng 
Published: May 2015

AbstractFragmentation frequently accompanies intact laser desorption ionization of a parent non‐volatile compound, desorption and dissociation dynamics has been a subject of intense studies over the past decade. As a preliminary lest system for future laser desorption study of energetic compounds such as explosives and propellents, we studied UV laser desorption ionization of melamine at a laser power density of approximately 4.4 MW/cm2. Several gas‐phase dissociation channels of the parent and fragment ions formed in UV laser desorption ionization of melamine films can be identified from their velocity distributions. A phenomenological desorption temperature of the order of 20000 K is estimated from fitting the experimental velocity distributions to Maxwellian functions.
Chaperone Function of Rat Lens α‐Crystallin
Authors: Ho Yuh , Hsu Ming‐Ching , Huang Fu‐Yung 
Published: May 2015

AbstractA solution of γ‐crystallin became turbid upon beating at 65 °C for 30 minutes; however, addition of α‐crystallin suppressed this thermal aggregation. It was found the effective chaperone function could be achieved with the molar ratio of α/γ greater than 1/20. In terms of crystallin subunit, five molecular α‐crystallin subunits could afford chaperone for one molecular γ‐crystallin. The gel filtration profile of the sample solution, containing α‐ and γ‐crystallins and preincubation at 65 °C for 30 minutes, showed complex formation between α‐ and γ‐crystallins, indicating α‐crystallin was bound to thermally denatured γ‐crystallin. A 1‐anilinonaphthalene‐8‐sulfonic acid (ANS) fluorescence study showed that α‐crystallin has more hydrophobic regions exposed after thermal incubation. In the presence of urea, both the α‐crystallin chaperone activity and the ANS fluorescence intensity decreased. Accordingly, hydrophobic regions of α‐crystallin play an indispensible role in its chaperone activity.