1,721,127 research outputs found
Stereoselective deamination of (5 ' RS)-5-methyl-2 ',3 '-isopropylidene adenosine catalyzed by adenosine deaminase: preparation of diastereomerically pure 5 '-methyl adenosine and inosine derivatives.
No full textAdenosine deaminase from calf intestine catalyzes the stereoselective deamination of (5'S)-5'-methyl-2',3'-isopropylidene adenosine to the corresponding inosine derivative, so that by enzymatic deamination of (5'RS)-5'-methyl-2',3'-isopropylidene adenosine, the diastereomerically pure (5'S)-inosine and the unreacted (5'R)-adenosine derivatives can be efficiently prepared
Lipase-catalyzed protection of the hydroxy groups of the nucleosides inosine and 2 '-deoxyinosine : a new chemoenzymatic synthesis of the antiviral drug 2 ',3 '-dideoxyinosine
No full textThe selective acylation of the hydroxy groups of the nucleosides inosine la and 2'-deoxyinosine Ib has been achieved in the presence of Candida antarctica and Pseudomonas sp. lipases in organic solvents ; starting from the 5'-acetyl derivative of 2'-deoxyinosine, an efficient chemoenzymatic synthesis of the antiviral drug 2',3'-dideoxyinosine has been achieve
2',3'-Isopropylidene group, a molecular scaffold to study the activity of adenosine and adenylate deaminase on adenosine analogues modified in the ribose moiety
No full text2',3'-Isopropylidene group can be used as a molecular scaffold for the introduction of modifications at 5' and 1' positions of adenosine and these modified nucleosides are used to evaluate the biocatalytic activity of adenosine and adenylate deaminase
1H, 13C and 15N NMR assignments for N- and O-acylethanolamines, important family of naturally occurring bioactive lipid mediators
No full textThe complete 1H, 13C and 15N NMR signal assignments of some N- and O-acylethanolamines, important family of naturally occurring bioactive lipid mediators, were achieved using one-dimensional and two-dimensional experiments (gs-HMQC and gs-HMBC)
Sintesi di 1-C-metil ribofuranosidi, intermedi per la preparazione di 1'-C-metil ribonucleosidi
No full textThe action of adenosine deaminase (EC 3.5.4.4.) on adenosine and deoxyadenosine acetates : The crucial role of the 5 '-hydroxy group for the enzyme activity
No full textFrom adenosine 1,2'-deoxyadenosine 3 and 3'-deoxyadenosine 5 all the acetates were prepared by lipase-catalyzed reactions. Only the acetates with free 5'-hydroxy group were deaminated by adenosine deaminase (ADA), confirming the crucial role of 5'-OH for the enzyme activity
Optimized synthesis and characterization of N-acylethanolamines and O-acylethanolamines, important family of lipid-signalling molecules
No full textThe endocannabinoid anandamide (N-arachidonoylethanolamine, AEA), a physiologically occurring bioactive compound on CB1 and CB2 receptors, has multiple physiological functions. Since the discovery of AEA additional non-cannabinoid endogenous compounds such as N-palmitoylethanolamine (PEA), and N-oleoylethanolamine (OEA) have been identified from mammalian tissues. Virodhamine (O-arachidonoylethanolamine, VA) is the only identified new member of the endocannabinoid family that is characterised by an ester linkage between acylic acid and ethanolamine instead of the amide linkage found in AEA and others non-cannabinoid N-acylethanolamines. It has been reported, as a cautionary note for lipid analyses, that VA can be produced nonenzymatically from AEA (and vice versa) as consequence of O,N-acyl migrations. O,N-acyl migrations are well documented in synthetic organic chemistry literature, but are not well described or recognized with regard to methods in lipid isolation or lipid enzyme studies. We here report an economical and effective protocol for large scale synthesis and characterization of some N- and O-acylethanolamines that could be useful as reference standards in order to investigate their possible formation in biological membranes, with potentially interesting biological properties
Complete 1H and 13C NMR spectral assignment of of α- and β-adenosine, 2'-deoxyadenosine and their acetate derivatives
No full text1H and 13C NMR chemical shifts of α- and β-anomers of adenosine, 2'-deoxyadenosine and their acetate derivatives were completely and definitely assigned using the concerted application of one- and two-dimensional experiments (gCOSY, gNOESY, gHSQC, and gHMBC). The influence of the stereochemistry of the purine base on the NMR data of the hydrogen and carbon atoms of the furanose moiety was investigated
Lipase-catalyzed monoprotection of 1,4-diols in an organic solvent using vinyl benzoate as acyl transfer agent
No full textLipase from Mucor miehei (MML) has been selected as the most suitable enzyme to catalyze the efficient monobenzoylation of 1,4-diols using vinyl benzoate as acyl transfer reagent in tert-butyl methyl ether. The regioselectivity of the monobenzoylation of 2-substituted-1,4-diols has been studied as well
Lipase-catalyzed deacylation by alcoholysis : A selective, useful transesterification reaction
No full textAlcoholysis is a transesterification reaction, according to which an ester RCOOR' reacts with an alcohol R(O)H with formation of another ester RCOOR and liberation of the alcohol R'OH. The deacylation may be catalyzed by a lipase in organic solvents and constitutes a useful step in the synthesis of complex molecules where different groups are present. The enzymatic deprotection procedure acquires a particular significance, considering the hydrophobic nature of the substrates and their solubility in organic solvents. In these non-conventional media lipases are still considerably active and a great variety of examples of regio- and chemoselectivity of the enzymatic deacylation have been reported. Application of resolution or asymmetrization procedures to the preparation of stereochemically pure products will also be examined and discussed. (copyright) 2006 Bentham Science Publishers Ltd
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