GABA is a major neurotransmitter in the central nervous system. Data on GABA and its analogues calculated by using the ab initio and the MNDO method were compared with data obtained experimentally. The structures of GABA analogues calculated by the ab initio method agree well with the experimental data. This finding suggests the high reliability of this method. However, the structures of GABA analogues calculated by the MNDO method reflect only some aspects of the experimental data. Therefore the MNDO method should be used only for carefully selected chemical compounds.
The amino group in GABA and its analogues was proved to be the major active site. The electrostatic potential around the amino group in these compounds seems to be related to their biological activity. The difference in the electrostatic potential between the receptor binding molecules and the neuronal uptake molecules suggests that the structure of post-synaptic receptors might differ from that of uptake receptors. This finding suggests that there are at least two GABA-A receptors. GABA molecules seem to have a high potential for binding to the two receptors because they are highly flexible and can readily change their conformation. These results indicate a high reliability of the data calculated by the molecular orbital method and suggest that this method provides us with useful information that cannot be obtained experimentally. 相似文献
Nine decomposition procedures for soil samples, such as via acid mixtures and fusion in open systems and microwave and autoclave
dissolution (in closed systems under elevated temperature and pressure) were assessed using certified soil reference materials.
The determination of various elements in solutions was performed by FAAS and ICP-OES and the results were compared with certified
values and with direct current arc OES analysis.
Received: 3 March 1997 / Revised: 30 May 1997 / Accepted: 3 June 1997 相似文献
The conformational energies, rotational barrier heights and molecular structures in C(CH2X)4 molecules (X=F, Cl, Br) based on molecular-mechanics calculations have been obtained. The results from these calculations are compared with the experimental gas-phase results. 相似文献
Conclusions The IR spectra of 5- and 8-hydroxyfurocoumarins and their esters, 5,8-disubstituted furocoumarins containing hydroxyl, methoxyl, and alkoxyl groups, and 4,5-dihydrofurocoumarins differ with respect to the intensity and number of the bands in the 1630–1500 cm–1 region of the spectrum. The integral intensities of the absorption bands in this frequency region differ markedly in the derivatives mentioned.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 5, pp. 355–359, 1969 相似文献
Temperature programmed reduction (TPR) has been used to study the redox behavior of Ni(II) ions in nickel sodium mordenite (NiNaM) and decationated nickel mordenite (NiHM). The TPR profiles suggest that Ni(II) ions occupy nonequivalent sites with different cooridination states in the mordenite. The reducibility of Ni(II) depends strongly on the zeolite acidity.
An alumina supported iron catalyst, active in CO hydrocondensation, has been shown by NGR sprectroscopy and magnetization measurement to undergo the redox reaction Fe+2H+Fe2++H2 at the surface. The number of atoms affected by H2 desorption has been calculated and corresponds to that obtained from CO chemisorption measurements.
The dihydronaphthodiphenazine ofKehrmann, which is according toBadger andPettit reported to be 14-o-aminophenyl-13,14-dihydro-5,8,13,14-tetraaza-6,7-benzopentaphene, is N-(o-aminophenyl)-benzo[a]phenazin-5-amine. This was proved by chemical and spectroscopic investigations. The structures of the derivatives prepared byBadger andPettit are also corrected and the acetylation processes are cleared up. 相似文献
Conclusions 1. On the basis of literature data on the structure of theVeratrum alkaloids, a definite law for the arrangement of the acyl radicals in these ester alkaloids and an interrelationship between the melting point and the structure of the substituent in the C7 position, and between the melting point and the types of amino alcohols upon which the ester alkaloids are based, has been found.2. The features mentioned may be used in studying the structure of theVeratrum ester alkaloids according to a scheme which we propose.Khimiya Prirodnykh Soedinenii, Vol. 6, No. 4, pp. 440–443, 1970 相似文献
A mechanism is proposed for the radiolysis of adsorbed N2O describing the experimental dependences of the radiation-chemical yields of O
st–
and N2 on N2O coverages.