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The Present issue of Current Organic Chemistry is dedicated to Enzymatic Catalysis. There is no doubt that enzymes are gaining an utmost important in organic chemistry thanks to their well-known selectivity (chemo-, regio- and enantio-) displayed under mild and environmental friendly reaction conditions. Moreover, the impressive development of molecular biology is making available an increasing number of enzymes with desired properties. We can reasonably affirm that biocatalysis has given its contribution to solve problems in any area of organic chemistry, showing that it is possible to find a biological equivalent for any chemical reaction (for instance, recent reports have described enzymes able to enzymes able to catalyze Diels-Alder reactions). The following collection of papers will offer a wide overview of the opportunities offered today by enzymatic catalysis. It is divided into two parts, the first devoted to the presentation of classes of enzymes not yet well-known to synthetic chemists and to new methodologies in biocataylsis. Martinkova and Mylerova contributed the first article on “Synthetic applications of nitrile-converting enzymes”, a subject that is relatively new for synthetic applications but that already sees several industrial applications on multi-tons scale. The second contribution by Poppe and Retey is entitled “Properties and synthetic applications of ammonia-lyases”. It is a detailed report on the fundamental biochemistry and on the structure determination of enzymes that in vivo catalyze double bonds formation by ammonia elimination. They synthetic potentiality relays on the reverse reaction, that is on the stereoselective addition of ammonia to double bonds to give natural and unnatural amino acids. The third review by Burton concerns “Laccases and phenol oxidases in organic synthesis”. Using molecular oxygen as oxidant, these enzymes provide effective methods to achieve asymmetric oxy-functionalisation reactions and routes tocontrolled and predictable formation of oxy-and hydroxylated products and to polymers. At variance, the fourth review by DeMartin and coworkers, “Biocatalysis in reaction mixtures with undissolved solid substrates and products”, is related to the development of a reaction methodology in which substrates and / or products are mainly undissolved. Using this approach reaction yields can be improved and the necessity to use organic solvents to shift the thermodynamic equilibrium toward synthesis can be reduced by product precipitation, which makes the synthesis catalyzed by hydrolytic enzymes favourable even in water. The second part of this special issue is devoted to practical applications. Brenna describes in details the “Enzymes-mediated synthesis of chiral communication substances: fragrances for perfumery applications”. The use of enzyme-mediated reaction for the preparation of enantiomerically enriched chiral fragrances are exemplified by taking into consideration the main floral, musk and woody-ambery odorants employed in fine and functional perfumery. The microbial / enzymatic processes finalized to the synthesis of chiral intermediates for bioactive molecules (antihypertensive drugs, anticholesterol drugs, anticancer agents, antiviral agents, receptor agonists, and anti-Alzheimer's drugs), mainly taken from the research carried out at Brystol-Myers Squibb, have been described in the contribution by Patel: “Microbial / enzymatic synthesis of chiral intermediates for pharmaceuticals: case studies from BMS”. The contribution by Uyame Kobayashi (“Enzymatic Synthesis of Polyphenols”) exemplifies the non-conventional use of enzymes for polymer production. Specifically, oxidative enzymes have been reported to catalyze the formation of various polyphenols, included analogous of natural lacquers (artificial urushi). Finally, Galante and Formantici present a comprehensive overview on: “Enzyme Applications in Detergency and Manufactoring Industries”. This review is particularly impressive not only for the details and completeness of the description but because it draw the attention of those chemists who are mainly dedicated to academic research, to a practical aspect of enzyme utilization that is commonly overlooked and concerns the quality of our everyday life. We kindly thank all the authors for their excellent efforts and we welcome any ideas for new topics to be discussed in future COC issues. |
