1,721,012 research outputs found
New industrial enzymatic catalysts for the functionalization of nucleosides of pharma interest
No full textImmobilizzazione di enzimi e mutagenesi sito-specifica
No full textL’immobilizzazione di enzimi su supporto solido consente di ottenere biocatalizzatori insolubili facilmente recuperabili dall’ambiente di reazione, riutilizzabili e caratterizzati da maggiore stabilità.
Per evitare approcci dispendiosi del tipo “trial and
error” nella scelta del supporto e della tecnica
di immobilizzazione, è fondamentale integrare
le informazioni strutturali sulla proteina con le
proprietà chimico-fisiche dei carrier utilizzati
per l’immobilizzazione. L’importanza di questa
strategia è stata confermata da tecniche di
mutagenesi sito-specifica e di analisi LC-MS/MS
utilizzate per determinare l’orientamento dell’enzima
sul supporto, descrittivo del grado di accessibilità
del sito attivo da parte dei substrati, e quindi
dell’attività dell’enzima immobilizzato
Protemics approaches to elucidate the orientation of immobilized enzymes: PGA, a case of study
No full textNucleoside phosphorylases from clostridium perfringens in the synthesis of 2',3'-dideoxyinosine
No full textFour Clostridium perfringens phosphorylases were subcloned, overexpressed and analyzed for their substrate specificity. DeoD(1) and PunA could use a variety of purine substrates, including an antiviral drug 2',3'-dideoxyinosine (ddI). In one-pot synthesis using Clostridium phosphorylases, 2',3'-dideoxyuridine and hypoxanthine were converted to ddI at yield of about 30%
A collection of immobilized and stabilized nucleoside phosphorylases for the synthesis of nucleoside analogues
No full textNucleoside phosphorylases (NPs; E.C. 2.4.2) catalyze the reversible cleavage of the glycosidic bond of (deoxy) ribonucleosides in the presence of inorganic orthophosphate to generate the nucleobase and a-D-(deoxy)ribose-1-phosphate. If a second nucleobase is added to the reaction medium the formation of a new nucleoside can result.
We have recently reported on the production and characterization of a purine nucleoside phosphorylase from A. hydrophila (AhPNPII). This PNP has been used in the synthesis of a few 6-substituted-purine-9-ribosides.
We have now isolated, cloned and expressed four new NPs from C. koseri, C. perfringens and S. pyogenes (CkPNPI, CkPNPII, CpUP and SpUP). Their substrate specificity has been investigated and compared to that of AhPNPII and other enzymes previously reported. CpUP, AhPNPII and CkPNPI were immobilized and used in the synthesis of antiviral araA and ddI
Coupling of Site-Directed Mutagenesis and Immobilization for the Rational Design of More Efficient Biocatalysts: The Case of Immobilized 3G3K PGA from E. coli
No full textWe have investigated the performances of the immobilized 3G3K mutant of the Penicillin G acylase (PGA) from E. coli obtained by site-directed mutagenesis. The 3G3K mutant, characterized by a tag consisting of three lysines alternating with three glycines at the end of the beta-chain, was previously reported to have a higher ratio between the rate of the antibiotic synthesis and the rate of the acylating agent hydrolysis than the wild type enzyme (vs/vh1 value). New immobilization studies were carried out with the 3G3K mutant by using different glyoxyl supports (activated with aldehyde groups). The catalytic properties of the new immobilized preparations were tested in the synthesis
of Cefamandole and Cefonicid by kinetically controlled N-acylation (kcNa). Compared to the commercial wild type PGA, the immobilized 3G3K acylase on glyoxyl agarose showed higher
synthetic performances, in all the tested reactions, in terms of reaction rates and yields
Immobilized and stabilized nucleoside phosphorylases for the enzymatic synthesis of modified pyrimidine nucleosides
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