1,721,069 research outputs found
Permanenza presso il “Medical College of Virginia”, Richmond, USA, come ricercatore visitatore ospite del Prof. Verne Schirch.
No full textDurante le visite sono stati condotti degli studi sul meccanismo d’azione della serina idrossimetiltrasferasi
Responsabile progetto “Professori visitatori” dell’Università di Roma “La Sapienza”, anno 2008. Docente invitato: Prof. Robert A. John, School of Biosciences, University of Cardiff, Regno Unito
No full textIl Professor Robert. A. John è un esperto di fama internazionale nello studio degli enzimi dipendenti dal piridossale 5'-fosfato (PLP). La sua attività di ricerca è
rivolta soprattutto alla comprensione del meccanismo catalitico di alcuni di questi enzimi, tramite indagini cinetiche nella fase pre-stazionaria e allo stato
stazionario, con substrati naturali e loro analoghi. Il Prof. John ha inoltre una lunga esperienza nella progettazione e sperimentazione di inibitori basati sul
meccanismo d'azione degli enzimi PLP-dipendenti.
La collaborazione con il nostro gruppo di ricerca, che fa capo al Prof. Francesco Bossa, è incominciata molti anni fa e si è protratta fino ad oggi in modo molto
fruttuoso, come testimoniano le numerose pubblicazioni su riviste biochimiche internazionali. Questa domanda di finanziamento ha l'obiettivo di facilitare il
confronto scientifico, già in atto, tra il proponente, gli altri membri del gruppo di ricerca e il Prof. John. In particolare, durante il soggiorno del Prof. John a Roma
verranno portati a termine, o iniziati, esperimenti su due enzimi PLP-dipendenti: la glutammico decarbossilasi (Gad) e la glutammato 1-semialdeide aminomutasi
(GSA-AM)
COMUNICAZIONE ORALE A CONGRESSO “The contribution of a conformationally-mobile, active-site loop to the reaction catalysed by glutamate semialdehyde aminomutase”, in the 2nd International Symposium on Vitamin B6, PQQ, Carbonyl Catalysis and Quinoproteins, Santa Fe, New Mexico, U.S.A., 31 October- 5 November 1999.
No full textCOMUNICAZIONE ORALE A CONGRESSO SU INVITO “Asymmetric reactivity of glutamate semialdehyde aminomutase with cyanoborohydride” in the European meeting on pyridoxal phosphate-dependent enzymes, Basel, Switzerland, 20-23 September 1997.
No full textDistribuzione dei chirotteri nella regione laziale (Italia centrale) e lista delle specie dell’area
No full textThe mechanism of high-yielding chiral syntheses catalysed by wild-type and mutant forms of aspartate aminotransferase
No full textThe ability of aspartate aminotransferase to catalyse p-elimination of a-amino acids that have a good leaving group at Cp has been exploited in the synthesis of novel amino acids by the inclusion of appropriate nucleophiles as co-substrates. Two compounds, L-serine 0-sulphate and 3-chloro-~-alaninew, ere used as p-elimination substrates. Nucleophiles used successfully as co-substrates were thiosulphate, 2-mercaptoethanol, mercaptoacetate and aminoethylthiopseudourea. The synthesis achieved using serine 0-sulphate and thiosulphate was found to produce sulphocysteine with a yield of 70%. Circular dichroism demonstrated that the compound was a single enantiomer and, therefore, that nucleophilic addition had taken place on the enzyme. The initial rate of synthesis was 10% of the rate at which the enzyme catalyses its normal transamination reaction. The synthetic reaction was accompanied by minor side reactions that led to small amounts of additional amino acid and 0x0 acid products through partitions of the main reaction at two stages in the mechanism. By mutating Arg292, which is the residue that binds the distal carboxyl group of natural substrates, the wild-type enzyme was converted to a form that could discriminate completely between serine 0-sulphate and chloroalanine as p-eliminating substrate. Similar alterations in nucleophile cosubstrate specificity were also observed. Whereas, for example, the wild-type enzyme catalysed syntheses between 3-chloroalanine and either mercaptoethanol or mercaptoacetate with equal facility, the Arg292Asp enzyme showed complete preference for mercaptoethanol. The system should be of general use in the synthesis of novel amino acids as single enantiomers with potentially interesting biological activities
Metodologie biochimiche. Principi e tecniche per l'espressione, la purificazione e la caratterizzazione delle proteine
No full textCOMUNICAZIONE ORALE A CONGRESSO SU INVITO “Studies on the evolutionary origins of pyridoxal-phosphate-dependent enzymes: catalytic promiscuity and reaction specificity”, in “Quo Vadis Proteomics”, Napoli, 26 Marzo 2001.
No full textBiomedical aspects of pyridoxal 5’-phosphate availability
No full textThe biologically active form of vitamin B6, pyridoxal 5'-phosphate (PLP), is a cofactor in over 160 enzyme activities involved in a number of metabolic pathways, including neurotransmitter synthesis and degradation. In humans, PLP is recycled from food and from degraded PLP-dependent enzymes in a salvage pathway requiring the action of pyridoxal kinase, pyridoxine 5'-phosphate oxidase and phosphatases. Once pyridoxal 5'-phosphate is made, it is targeted to the dozens different apoenzymes that need it as a cofactor. The regulation of the salvage pathway and the mechanism of addition of PLP to the apoenzymes are poorly understood and represent a very challenging research field. Severe neurological disorders, such as convulsions and epileptic encephalopathy, result from a reduced availability of pyridoxal 5'-phosphate in the cell, due to inborn errors in the enzymes of the salvage pathway or other metabolisms and to interactions of drugs with PLP or pyridoxal kinase. Multifactorial neurological pathologies, such as autism, schizophrenia, Alzheimer's disease, Parkinson's disease and epilepsy have also been correlated to inadequate intracellular levels of PLP
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