Structural and Mechanistic Aspects

MeHNL is also capable of catalyzing the nitroaldol reaction, albeit with lower activity and selectivity, whereas PaHNL showed no activity at all [116]. The only (P)-selective enzyme with a a/p-hydrolase fold (like HbHNL and MeHNL), AfHNL, catalyzed the Henry reaction of aromatic aldehydes and MeNO [117]. 

LuHNL from L. usitatissimum shows high sequence similarity to the Zn -alcohol dehydrogenase superfamily [66,139]. However, no structure has been published so far. HNL activity is also found in the cupin fold superfamily, which was discovered recently, and a novel group of metal-dependent bacterial HNLs has been reported [17,74,75]. 

25 HYDROXYNITRILE LYASES FOR BIOCATALYTIC SYNTHESIS OF CHIRAL CYANOHYDRINS 

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In the first chapter, devoted to thiazole itself, specific emphasis has been given to the structure and mechanistic aspects of the reactivity of the molecule most of the theoretical methods and physical techniques available to date have been applied in the study of thiazole and its derivatives, and the results are discussed in detail The chapter devoted to methods of synthesis is especially detailed and traces the way for the preparation of any monocyclic thiazole derivative. Three chapters concern the non-tautomeric functional derivatives, and two are devoted to amino-, hydroxy- and mercaptothiazoles these chapters constitute the core of the book. All discussion of chemical properties is complemented by tables in which all the known derivatives are inventoried and characterized by their usual physical properties. This information should be of particular value to organic chemists in identifying natural or Synthetic thiazoles. Two brief chapters concern mesoionic thiazoles and selenazoles. Finally, an important chapter is devoted to cyanine dyes derived from thiazolium salts, completing some classical reviews on the subject and discussing recent developments in the studies of the reaction mechanisms involved in their synthesis. 

Structural and Mechanistic Aspects of Additions of Nucleophiles to Diazonium Ions... 

The biologically uncommon Ni center associated with FeS clusters is a powerful and unique catalytic unity. In this chapter we have reviewed the structural and mechanistic aspects of three NiFeS centers the active site of hydrogenase and Clusters A and C of CODH/ACS. In the former, the association of a Ni center with the most unusual FeCOCN2 unit is a fascinating one. Model chemists, spectroscopists, and crystallographers have joined efforts to try and elucidate the reaction mechanism. Although a consensus is being slowly reached, the exact roles of the different active site components have not yet been fully established. Ni appears to be the catalytic center proper, whereas the unusual Fe center may be specially suited to bind a by-... 

Because there exist a number of reviews which deals with the structural and mechanistic aspects of high-valent iron-oxo and peroxo complexes [6,7], we focus in this report on the application and catalysis of iron complexes in selected important oxidation reactions. When appropriate we will discuss the involvement and characterization of Fe-oxo intermediates in these reactions. 

Structural and Mechanistic Aspects of Copper Catalyzed Atom Transfer Radical Polymerization... 

ATRP, other factors, such as solvent and temperature, must also be taken into consideration. Typical monomers and alkyl halide initiators that are used in ATRP are shown in Scheme 5 [47], The copper complex is perhaps the most important component of this catalytic system because it regulates the dynamic equilibrium between dormant and active species. In this article, structural and mechanistic aspects of copper-catalyzed ATRP are discussed. 

The groups of Philipsborn [84], Heaton [85-88] and Mann [89-91] have used ° Rh NMR extensively to elucidate structural and mechanistic aspects of a wide variety of metal carbonyl and metal cluster complexes. Further, Zamaraevl [92] has shown that NMR studies on several quadrupolar nuclei, e. g. Mo, help with the characterization of the alkyl peroxo-complexes, which are thought to be inter-... 

Structural and Mechanistic Aspects of the Dehydration of Isomeric Butyl Alcohols over Porous Aluminosilicate Acid Catalysts... 

Fundamental knowledge of the structure, function and mechanism of DNA-modifying enzymes has been important not only in understanding how these enzymes perform a myriad of chemical reactions Ml vZvo but also for the development of the field of recombinant DNA technology. The functions of the major groups of enzymes in deoxyribonucleic acid synthesis, hydrolysis and modification are reviewed, as well as some structural and mechanistic aspects of the restriction endonucleases, ligases and polymerases. 

The goal of diiron model chemistry is to develop small molecule systems that accurately reproduce spectroscopic, structural, and more ambitiously, reactivity aspects of driron metaUoproteins. Despite being structurally similar, diiron enzymes carry out a variety of catalytic processes see Iron Proteins with Dinuclear Active Sites)Advancements in the synthesis and characterization of small molecule mimics for nonheme diiron enzymes have been tremendous in the last decade. Biomimetic studies have been carried out in efforts to reproduce the structural and functional aspects of these biocatalysts. Although this has been a challenging endeavor, much information regarding the structural and mechanistic aspects of catalytic intermediates has been obtained. 

C. AmatoreandA. Jutand, Structural and Mechanistic Aspects of Palladium-Catalyzed Cross-Couplings, in Handbook of Organopalladium Chemistry for Organic Synthesis , ed. E. Negishi, John Whey Sons, Hoboken, NJ, 2002, p. 943. 

W. H. Starnes Jr., Structural and mechanistic aspects of the thermal degradation of poly(vinyl chloride). Prog. Polym. ScL, 27, 2133-2170 (2002). 

Amatore, C., Jutand, A. Structural and mechanistic aspects of palladium-catalyzed cross-coupling. Handbook of Organopalladium Chemistry for Organic Synthesis 2002,1,943-972. 

Backlund M, Weidolf L, Ingelman-Sundberg M. Structural and mechanistic aspects of transcriptional induction of cytochrome P450 1A1 by benzimidazole derivatives in rat hepatoma H4IIE cells. Eur J Biochem/FEBS 1999 26 66-71. 

During the past 12 years (the period covered by this review), very few new thcrmochromic molecular systems have been reported. The main families of compounds have continued to be the major focus of interest, with only a shift in the balance between them for example, spiropyrans have been less studied (in terms of development of new compounds) while interest in anils has increased. There has also been a shift away from work essentially devoted to the description of new compounds, as, in recent years, the attention of authors has mainly been directed toward thermodynamic, kinetic, structural, and mechanistic aspects. For this purpose, a large variety of techniques, including not only spectroscopic techniques (UV-visible, NMR) but also X-ray diffraction and theoretical calculations, have been employed, leading to a better knowledge of the fundamental aspect of the thermochromism of organic compounds. 

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