Enzymatic Mechanisms Involved in Evasion of Fungi to the Oxidative Stress: Focus on Scedosporium apiospermum

The airways of patients with cystic fibrosis (CF) are frequently colonized by various filamentous fungi, mainly Aspergillus fumigatus and Scedosporium species. To establish within the respiratory tract and cause an infection, these opportunistic fungi express pathogenic factors allowing adherence to the host tissues, uptake of extracellular iron, or evasion to the host immune response. During the colonization process, inhaled conidia and the subsequent hyphae are exposed to reactive oxygen species (ROS) and reactive nitrogen species (RNS) released by phagocytic cells, which cause in the fungal cells an oxidative stress and a nitrosative stress, respectively. To cope with these constraints, fungal pathogens have developed various mechanisms that protect the fungus against ROS and RNS, including enzymatic antioxidant systems. In this review, we summarize the different works performed on ROS- and RNS-detoxifying enzymes in fungi commonly encountered in the airways of CF patients and highlight their role in pathogenesis of the airway colonization or respiratory infections. The potential of these enzymes as serodiagnostic tools is also emphasized. In addition, taking advantage of the recent availability of the whole genome sequence of S. apiospermum, we identified the various genes encoding ROS- and RNS-detoxifying enzymes, which pave the way for future investigations on the role of these enzymes in pathogenesis of these emerging species since they may constitute new therapeutics targets

Dewar-benzene derivates: Synthesis, isomerization, hydrogenation

Applied SciencesApplied Science

Hydrogenation and hydrogenolysis in synthetic organic chemistry

The major aim of this book is to provide preparative organic chemists with the insight and the know-how necessary to apply catalytic hydrogenation and hydrogenolysis to synthetic problems. Several texts on hydrogenation and hydrogenolysis are available, but the authors feel that many chemists will welcome a book in which more attention has been paid to the mechanistic background of these reactions and its relation to synthetic problems. In this book a special effort has been made to present the various types of hydrogenation and hydrogenolysis reactions from both a mechanistic and a preparative point of view. After a short general introduction concerning catalyst systems and reaction conditions, hydrogenation and hydrogenolysis are discussed separately. The chapters have been organized according to a logical arrangement of the various bonds which can be reduced with hydrogen in the presence of a catalyst system. Reaction rate, selectivity, and steric course of the hydrogen addition are dealt with in relation to the reaction mechanism. Numerous synthetically interesting examples exemplify these aspects as well as the scope and limitations of the reactions.Applied Science

Enzymatic ammoniolysis of amino acid derivatives

The ammoniolysis of amino acid esters and their derivatives was performed with lipases and proteases yielding the corresponding amino acid amides with moderate to high enantioselectivity. Phenylglycine methyl ester racemized slowly under the reaction conditions

Method of preparing cross-linked enzyme particles

The invention relates to a method of preparing cross-linked enzyme particles using a cross-linking agent. According to the invention, the enzyme particles are formed and subsequently cross-linked using a cross-linking agent having at least n reactive groups where N>=3 and a molecular weight of >2,000 Da. The method according to the invention allows for obtaining enzyme particles having a higher enzyme activity than enzyme particles cross-linked according to the state of the art.Applied Science

A PROCESS FOR CARRYING OUT ENZYMATICALLY CATALYZED CONVERSIONS OF ORGANIC COMPOUNDS

Abstract of WO 9507359 (A1) A process for carrying out enzymatically catalyzed conversions of organic compounds comprises reacting an ester of an organic acid in a liquid organic phase with ammonia in the presence of a hydrolytic enzyme such as a lipase, esterase or protease. The process permits the highly enantioselective preparation of enantiomers of amides, esters and/or alcohols in good yield from racemic starting material under very mild reaction condition