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1.
Bernd M. Rode Michael G. Schwendinger Sirirat U. Kokpol Supot V. Hannongbua Supa Polman 《Monatshefte für Chemie / Chemical Monthly》1989,120(11):913-921
Summary Linear models for the relation between electronic structure and antimalarial activity of chloroquine drugs have been investigated, based on CNDO/2 molecular orbital calculations. The results indicate that changes in electron density on the atoms N1, N2, C4, C9, and C10 have the strongest influence on the pharmacological activity, so that these atoms can be assumed to form the main active center of these drugs. Correlations improve, if substitution on the nucleus of chloroquine and side chain variations are treated separately. The models found seem to be a useful tool for designing new drugs within the chloroquine series.
Quantenchemisch-pharmakologische Untersuchungen von Antimalaria-Wirkstoffen
Zusammenfassung Auf der Basis von CNDO/2-Rechnungen wurden lineare Modelle für die Relation zwischen Elektronenverteilung und der Antimalaria-Aktivität von Chlorochinen untersucht. Es zeigte sich, daß Veränderungen in den Elektronendichten der Atome N1, N2, C4, C9 und C10 den stärksten Einfluß auf die pharmakologische Wirkung haben. Es kann somit angenommen werden, daß diese Atome die hauptsächlich aktiven Zentren der Verbindung sind. Die Korrelation wird verbessert, wenn die Substitution am Chlorochin-Kern und Variationen der Seitenketten separat behandelt werden. Die aufgefundenen Modellvorstellungen sollten ein nützliches Werkzeug zur gezielten Synthese neuer Wirkstoffe innerhalb der Chlorochin-Reihe darstellen.相似文献
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Taechapoempol K Sreethawong T Rangsunvigit P Namprohm W Thamprajamchit B Rengpipat S Chavadej S 《Applied biochemistry and biotechnology》2011,164(2):204-219
The three highest hydrolysis-capacity-value isolates of Bacillus subtilis (A 002, M 015, and F 018) obtained from Thai higher termites, Microcerotermes sp., under different isolation conditions (aerobic, anaerobic, and anaerobic/aerobic) were tested for cellulase activities—FPase,
endoglucanase, and β-glucosidase—at 37 °C and pH 7.2 for 24 h. Their tolerance to an ionic liquid, 1-butyl-3-methylimidazolium
chloride ([BMIM]Cl), was also investigated. The results showed that the isolate M 015 provided the highest endoglucanase activity
whereas the highest FPase and β-glucosidase activities were observed for the isolate F 018. The isolate F 018 also showed
the highest tolerance to [BMIM]Cl in the range of 0.1–1.0 vol.%. In contrast, the isolate A 002 exhibited growth retardation
in the presence of 0.5–1.0 vol.% [BMIM]Cl. 相似文献
4.
Kumarn S Oelke AJ Shaw DM Longbottom DA Ley SV 《Organic & biomolecular chemistry》2007,5(16):2678-2689
A sequential, organocatalysed asymmetric reaction to access chiral 1,2-oxazines and chiral pyridazines is reported, which proceeds in moderate to good yields and good to excellent enantioselectivities. 相似文献
5.
Nueangaudom A Lugsanangarm K Pianwanit S Kokpol S Nunthaboot N Tanaka F 《Physical chemistry chemical physics : PCCP》2012,14(8):2567-2578
The structural basis for the temperature-induced transition in the D-amino acid oxidase (DAAO) monomer from pig kidney was studied by means of molecular dynamic simulations (MDS). The center to center (Rc) distances between the isoalloxazine ring (Iso) and all aromatic amino acids (Trp and Tyr) were calculated at 10 °C and 30 °C. Rc was shortest in Tyr224 (0.82 and 0.88 nm at 10 and 30 °C, respectively), and then in Tyr228. Hydrogen bonding (H-bond) formed between the Iso N1 and Gly315 N (peptide), between the Iso N3H and Leu51 O (peptide) and between the Iso N5 and Ala49 N (peptide) at 10 °C, whilst no H-bond was formed at the Iso N1 and Iso N3H at 30 °C. The H-bond of Iso O4 with Leu51 N (peptide) at 10 °C switched to that with Ala49 N (peptide) at 30 °C. The reported fluorescence lifetimes (228 and 182 ps at 10 and 30 °C, respectively) of DAAO were analyzed with Kakitani and Mataga (KM) ET theory. The calculated fluorescence lifetimes displayed an excellent agreement with the observed lifetimes. The ET rate was fastest from Tyr224 to the excited Iso (Iso*) at 10 °C and from Tyr314 at 30 °C, despite the fact that the Rc was shortest between Iso and Tyr224 at both temperatures. This was explained by the electrostatic energy in the protein. The differences in the observed fluorescence lifetimes at 10 and 30 °C were ascribed to the differences in electron affinity of the Iso* at both temperatures, in which the free energies of the electron affinity of Iso* at 10 and 30 °C were -8.69 eV and -8.51 eV respectively. The other physical quantities related to ET did not differ appreciably at both temperatures. The electron affinities at both temperatures were calculated with a semi-empirical molecular orbital method (MO) of PM6. Mean calculated electron affinities over 100 snapshots with 0.1 ps intervals were -7.69 eV at 10 °C and -7.59 eV at 30 °C. The difference in the calculated electron affinities, -0.11 eV, was close to the observed difference in the free energies, -0.18 eV. The present quantitative analysis predicts that the highest ET rate can occur from a donor with longer donor-acceptor distance, which was explained by differences in electrostatic energy. 相似文献
6.
Somsak Tonmunphean Sirirat Kokpol Vudhichai Parasuk Peter Wolschann Rudolf H. Winger Klaus R. Liedl Bernd M. Rode 《Journal of computer-aided molecular design》1998,12(4):397-397
Based on the belief that structural optimization methods, producing structures more closely to the experimental ones, should give better, i.e. more relevant, steric fields and hence more predictive CoMFA models, comparative molecular field analyses of artemisinin derivatives were performed based on semiempirical AM1 and HF/3-21G optimized geometries. Using these optimized geometries, the CoMFA results derived from the HF/3-21G method are found to be usually but not drastically better than those from AM1. Additional calculations were performed to investigate the electrostatic field difference using the Gasteiger and Marsili charges, the electrostatic potential fit charges at the AM1 level, and the natural population analysis charges at the HF/3-21G level of theory. For the HF/3-21G optimized structures no difference in predictability was observed, whereas for AM1 optimized structures such differences were found. Interestingly, if ionic compounds are omitted, differences between the various HF/3-21G optimized structure models using these electrostatic fields were found. 相似文献
7.
Chungjatupornchai W Kamlangdee A Fa-Aroonsawat S 《Applied biochemistry and biotechnology》2011,164(7):1048-1057
The display of proteins to cyanobacterial cell surface is made complex by combination of Gram-positive and Gram-negative features
of cyanobacterial cell wall. Here, we showed that Synechococcus outer membrane protein A (SomA) can be used as an anchoring motif for the display of organophosphorus hydrolase (OPH) on
cyanobacterial cell surface. The OPH, capable of degrading a wide range of organophosphate pesticides, was fused in frame
to the carboxyl-terminus of different cell-surface exposed loops of SomA. Proteinase K accessibility assay and immunostaining
visualized under confocal laser scanning microscopy demonstrated that a minor fraction of OPH with 12 histidines fused in
frame with the third cell-surface exposed loop of SomA (SomAL3-OPH12H) was displayed onto the outermost cell surface with
a substantial fraction buried in the cell wall, whereas OPH fused in frame with the fifth cell-surface exposed loop of SomA
(SomAL5-OPH) was successfully translocated across the membrane and completely displayed onto the outermost surface of Synechococcus. The successful display of the functional heterologous protein on cell surface provides a useful model for variety of applications
in cyanobacteria including screening of polypeptide libraries and whole-cell biocatalysts by immobilizing enzymes. 相似文献
8.
Nunthaboot N Pianwanit S Kokpol S Tanaka F 《Physical chemistry chemical physics : PCCP》2011,13(13):6085-6097
The mechanism of photoinduced electron transfer (PET) from the aromatic amino acids (Trp32, Tyr35 and Trp106) to the excited flavin mononucleotide (FMN) in the wild type (WT) and four single amino acid substitution isomers (E13T, E13Q, W32A and W32Y) of FMN binding protein (FBP) from the Desulfovibrio vulgaris (Miyazaki F) were simultaneously analyzed (Method A) with the Marcus-Hush (MH) theory and Kakitani-Mataga (KM) theory using ultrafast fluorescence dynamics of these proteins. In addition, the PET mechanism of the WT, E13T and E13Q FBP systems (Method B) were also analyzed with both MH and KM theories. The KM theory could describe all of the experimental fluorescence decays better than the MH theory by both Methods A and B. The PET rates were found to largely depend on the electrostatic energies between photo-products, isoalloxazine (Iso) anion and the PET donor cations, and the other ionic groups, and hence on static dielectric constants. The dielectric constant (ε(0)(DA)) around the PET donors and acceptor was separately determined from those (ε(0)(j), j = WT, E13T, E13Q, W32Y and W32A) in the domain between the Iso anion or the donor cations and the other ionic groups in the proteins. The values of ε(0)(DA) were always lower than those of ε(0)(j), which is reasonable because no amino acid exists between the PET donors and acceptor in all systems. The values of the dielectric constants ε(0)(j) (j = WT, E13T and E13Q) were similar to those obtained previously from the analysis of the crystal structures and the average lifetimes of these FBP proteins. Energy gap law in the FBP systems was examined. An excellent parabolic function of the logarithms of the PET rates was obtained against the total free energy gap. The PET in these FBP isomers mostly took place in the so-called normal region, and partly in the inverted region. 相似文献
9.
Prayong B. Doungdee Sirirat U. Kopkol Bernd M. Rode 《Monatshefte für Chemie / Chemical Monthly》1987,118(6-7):691-697
The influence of a full first hydration shell on the energy barriers related to conformational changes of glycine has been studied by means of molecular orbital calculations. The energy optimized pathway is discussed and compared with that of the isolated molecule, evaluating the possibility of corotation of the hydration shell during conformational changes.
Der Einfluß der Hydratation auf die Rotationsbarrieren von Glycin
Zusammenfassung Es wurde mit Hilfe einer Molekülorbitalrechnung der Einfluß der vollen ersten Hydrathülle auf Rotationsbarrieren bei Konformationsänderungen im Glycinmolekül untersucht. Es wird ein energieoptimierter Rotationsverlauf diskutiert und mit dem des freien Moleküls verglichen, wobei insbesondere die Möglichkeit einer Korotation der Hydrathülle beachtet wird.相似文献
10.
Sirirat U. Kokpol Supot V. Hannongbua Jamras P. Limtrakul 《Monatshefte für Chemie / Chemical Monthly》1989,120(6-7):491-499
Summary The influence of Na+ on hydrogen bonds of the OH O and NH O type between an aliphatic amino acid (glycine zwitterion) and water is investigated byab initio calculations with minimal Gaussian basis sets. Distortion of the hydration shell caused by Na+, and interaction energies contributing to the over-all stabilization are discussed.
Der Einfluß von Na+ auf die benachbarten Wasserstoffbindungen in aliphatischen Aminosäuren
Zusammenfassung Der Einfluß von Na+ auf die Wasserstoffbindungen vom OH O- und NH O-Typ in aliphatischen Aminosäuren (Glycin-Zwitterion) und Wasser wurde mittelsab initio Berechnungen mit einem minimalen Gausschen Basissatz untersucht. Die durch Na+-Ionen hervorgerufenen Verzerrungen der Hydratationsschale und die zur Gesamtstabilisierung beitragenden Wechselwir-kungsenergien werden diskutiert.相似文献