Biomedical subjects
Publications and source records attributed to G Taibi.
In the cerebral hemispheres of the chick embryo, the level of nucleoside phosphotransferase activity is much higher than that of thymidine kinase and it increases progressively during development up to the adult stage. Therefore nucleoside phosphotransferase is not coupled with DNA synthesis.
The prevalence of probable multiple sclerosis in Agrigento city on the south-west coast of Sicily is at least 2 per 100 000. This is likely to be a considerable underestimate of the true prevalence because the study presented particular difficulties in that the city is far from the neurological centres of Palermo. Catania, and Messina. There is no neurological department at either the general or the psychiatric hospital in Agrigento and there was a low awareness of the disease among the doctors in the city. Most of the patients were diagnosed in other centres. Agrigento is a good example of the difficulties of studying multiple sclerosis in a rural city which has no special interest in neurological problems and is far from a neurological centre. Studies in such centres must be pursued with great enthusiasm and over a long period of time, and all available sources of information in the city, medical and lay, and in other cities, must be utilised if a high proportion of the patients is to be found.
This paper describes a purification procedure and some properties of a nonspecific nucleoside phosphotransferase of chick embryo, an activity which catalyzes the transfer of chick embryo, an activity which catalyzes the transfer of the phosphate ester from a deoxyribonucleotide or a pyrimidine ribonucleotide to a deoxyribonucleoside acceptor. The enzyme is very unstable to heat, dilution and dialysis and it is almost entirely inactivated by DEAE-cellulose chromatography or gel filtration. A marked enhancement in its stability is caused by numerous nucleotides. In these experiments at least 920-fold purification was obtained by using dTTP (50 microM) as nucleotide protector. The enzyme, purified in presence of dTTP, has a molecular weight about 270,000, an isoelectric point of 6.27, a pH optimum of 8.8 and is stable at 37 degrees C at least for 10 min. In absence of nucleotide protector, nucleoside phosphofranserferase is connected at 37 degrees C or by gel filtration in a very small active form with a lower molecular weight (about 30,000) and a pH optimum of 7.6.
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A nucleoside phosphotransferase purified about 40fold from chick embryos utilizes efficiently as phosphate donors deoxyribonucleoside and pyrimidine ribonucleoside monophosphates, whereas the pyrimidine deoxyribonucleoside appear to be the preferred acceptors of phosphate. The enzyme is very unstable to heat, dilution and dialysis. A marked enhancement in the stability is caused by nucleotides and it seems associated with the formation of an aggregated state of the protein.
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Explore the source record for details and available documents.