Structural and Chemical Studies

A base isolated from Euchresta japonica by extraction with methanol was shown by spectroscopic studies and by its synthesis from (-)-cystisine and methyl bromoacetate to be methyl 12-cytisine acetate (4). This compound is apparently an artifact derived from the new alkaloid (5) extraction of the plant with aqueous ethanol gave the latter compound as its zwitterion, and the methyl ester (4) was not detected.  

Reductive formylation of angustifoline (6) leads to N-methylangustifoline in methanol and to an isomer (7) of the latter in aqueous solution. Derivatives of lupinine, epilupinine, and cytisine have been prepared. 

A fresh investigation of the constituents of Anagyris foetida resulted in the isolation of a new alkaloid although the structure has not been fully established, mass spectroscopy indicates that the compound is a hydroxy-anagyrine (8) with a hydroxy-group in ring d. 

An X-ray study of the dihydrate of (+)-lupanine hydrochloride, cf. (10), showed that ring c was in the boat conformation.  

Sophora franchetiana contains the most interesting quinolizidine alkaloid of the year, tsukushinamine. The latter is a new type of C15 tetracyclic alkaloid, and structure (13) was proposed for it on the basis of spectroscopic studies. The i.r. and u.v. spectra indicated that a non-conjugated lactam group was present, and a 

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A crude toxic principle, which we now know to be only about 0.2% pure, was obtained by Yoshizumi Tahara (9,10) in 1909. He named this tetrodotoxin. In 1950 Aikira Yokoo (11) obtained pure crystalline tetrodotoxin. The purification was further developed by Tsuda and co-workers (12) so that the production of the necessary amounts of tetrodotoxin for structural and chemical studies could be achieved. From 1000 kg (1 ton) of pufferfish ovaries they obtained 8-10 g of tetrodotoxin. 

Crabtree RH. Dihydrogen complexes some structural and chemical studies. Ace Chem Res 1990 23(4) 95-101. 

Lensky, Y., Gassier P., Rosa, S. and Grandperrin, D. (1991). Induction of balling in worker honeybees Apis mellifera L.) by stress pheromone from Koschewnikow glands of queen bees Behavioral, structural and chemical study. Comp. Biochem. Physiol. IlOA, 585-594. 

R.H. Crabtree - Dihydrogen Complexes Some Structural and Chemical Studies,... 

There is a large volume of contemporary literature dealing with the structure and chemical properties of species adsorbed at the solid-solution interface, making use of various spectroscopic and laser excitation techniques. Much of it is phenomenologically oriented and does not contribute in any clear way to the surface chemistry of the system included are many studies aimed at the eventual achievement of solar energy conversion. What follows here is a summary of a small fraction of this literature, consisting of references which are representative and which also yield some specific information about the adsorbed state. 

An exploration of possible relationships between structural and chemical decomposition of bone. Proceedings of the I World Congress on Mummy Studies. Museo Arqueologico y Etnografico doe Tenerife, Islas Canarias (Spain) 549-558. 

Analytical electron microscopy permits structural and chemical analyses of catalyst areas nearly 1000 times smaller than those studied by conventional bulk analysis techniques. Quantitative x-ray analyses of bismuth molybdates are shown from lOnm diameter regions to better than 5% relative accuracy for the elements 61 and Mo. Digital x-ray images show qualitative 2-dimensional distributions of elements with a lateral spatial resolution of lOnm in supported Pd catalysts and ZSM-5 zeolites. Fine structure in CuLj 2 edges from electron energy loss spectroscopy indicate d>ether the copper is in the form of Cu metal or Cu oxide. These techniques should prove to be of great utility for the analysis of active phases, promoters, and poisons. 

However, these techniques may not detect important phenomena taking place on the surface of or within the interior of individual Inm-to Ipm-diameter inorganic particles that are s3rnthesized specifically for their catalytic activity. AEM is an extremely useful technique for analysis of the individual heterogeneous catalyst particle and its relationship to various supporting materials. Structural and chemical analyses can be obtained from specimen regions nearly 1000 times smaller than those studied by conventional bulk analysis techniques. This high lateral spatial... 

Megli and Sabatini [55] studied the phospholipid bilayers after lipoperoxidation. Phospholipids were oxidized, and the oxidized phospholipid species were separated by PLC and estimated by EPR. It was shown that the early stages of lipoperoxidation brought about disordering of the phospholipid bilayer interior rather than fluidity alterations and that prolonged oxidation may result in a loss of structural and chemical properties of the bilayer until the structure no longer holds. 

Kumar, C.V. and Choudhari A. (2000) Proteins immobilized at the galleries of layered alpha-zirconium phosphate structure and activity studies. Journal of the American Chemical Society, 122, 830-837. 

This procarcinogen undergoes metabolic conversion to benzo[a]pyrene diol epoxides, BPDEs (5,28-31), which have been the focus of structural and conformational studies by theoretical and experimental methods. These chemically reactive BPDEs are involved in covalent binding to DNA (13-22). 

Prior to the advent of site-directed mutagenesis as a viable technique for the production of specifically modified proteins, the last major event to exert a major influence on the study of protein structure and function was the development of X-ray diffraction analysis for the detailed structural analysis of macromolecules. In the intervening thirty years, the availability of protein structures obtained in this manner combined with a wide range of physical and chemical studies of these proteins allowed development of substantial insight into the relationship between the structure of a protein and its functional attributes. There was some reason to expect, therefore, that functional characterization of specifically mutated proteins based on understanding developed with more classical techniques should permit efficient confirmation of existing hypotheses, particularly for proteins for which the available literature is as extensive as that for cytochrome c. 

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