1,721,115 research outputs found
Biocatalysis in peptide synthesis: from non aqueous media to solid phase synthesis
No full textSelectivity and efficiency of enzymes can be fruitfully exploited in peptide chemistry for amide bond formation1, protection/deprotection strategies2, targetted modifications of side chains and also for selective cleavage of linkers in solid phase synthesis3.
Recent advances in applied biocatalysis enable the enzymatic peptide synthesis in rather extreme non conventional conditions, ranging from organic media, substrates anchored on solid supports and substrates mainly undissolved in nearly solvent-less systems4. Moreover, the technological advances in enzyme discovery and engineering have led to a broad range of efficient and selective enzymes to be used at lab scale.
Examples of how different „non conventional“ synthetic methodologies can match various peptide synthetic purposes will be presented. In a number of cases, translating an enzymatic reaction into an efficient biocatalysed process of practical applicability still remains a major bottleneck that hampers the full exploitation of the catalytic potential of enzymes. The use of computational tools, as modelling and statistics, will be discussed in the perspective of a more rational and effective exploitation of the technological and scientific advances in the field of applied biocatalysis, with particular regard to the field of peptide chemistry
Immobilisation of Enzymes and Control of Water Activity in Low-Water Media: Properties and Applications of Celite R-640 (Celite Rods)
No full text
CONTROL OF ENZYME HYDRATION IN PENICILLIN AMIDASE CATALYSED SYNTHESIS OF AMIDE BOND
No full textPenicillin amidase catalyses the synthesis of amide bond in very high yield (>98%), using equimolar concentrations of the amine and the phenylacetic components. In situ hydrated phosphates were employed for controlling the water activity in a benzene/water system (97:3 v/v), where the water is taken up by the salt with formation of the hydrated species
ACTIVITY OF IMMOBILISED PENICILLIN AMIDASE IN TOLUENE AT CONTROLLED WATER ACTIVITY
No full textJ. MOL. CATAL. B: ENZYMATI
Understanding Enzyme Immobilisation
No full textEnzymes are versatile catalysts in the laboratory and on an industrial scale. To broaden their applicability in the laboratory and to ensure their (re)use in manufacturing the stability of enzymes can often require improvement. Immobilisation can address the issue of enzymatic instability. Immobilisation can also help to enable the employment of enzymes in different solvents, at extremes of pH and temperature and exceptionally high substrate concentrations. At the same time substrate-specificity, enantioselectivity and reactivity can be modified. However, most often the molecular and physical–chemical bases of these phenomena have not been elucidated yet. This tutorial review focuses on the understanding of enzyme immobilisation
Thermodynamic analysis of enzyme enantioselectivity: a statistical approach by means of new differential HybridMIF descriptors
No full textThe study of relationships between substrate structure and enzyme stereoselectivity was approached by means of a new molecular descriptor: the “differential Hybrid Molecular Interaction Field” (dH-MIF). The descriptor was conceived with the purpose of combining enthalpic and entropic information related to enzyme–enantiomer interactions. The dH-MIFs were developed based on experimental data previously published by the group of Karl Hult on the enantioselectivity of the W104A mutant of lipase B from Candida antarctica, which is endowed with an enlarged stereoselectivity pocket. Because of the increased conformational freedom of substrates, the entropic contribution to enantiodiscrimination is particularly relevant in kinetic resolution of alcohols catalyzed by this enzyme. By combining molecular dynamic simulations and GRID analysis the new dH-MIF descriptors proved to be able to extract both enthalpic and entropic information from models of the tetrahedral intermediates of enantiomers
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