PubMed Health⌕ Search

Biomedical subjects

R Pagani

Publications and source records attributed to R Pagani.

159 records · Page 9Linked to original sources
PubMedDate not supplied

Properties of rat liver L-threonine deaminase.

We have studied several properties of rat liver L-threonine deaminase: (1) the affinity for the two substrates, L-serine and L-threonine; (2) the threonine/serine activity ratio which changes with increasing pH; (3) the activation, by pyridoxal 5'-phosphate which is linked to the nonprotonated form of the coenzyme and to at least an -SH group of the enzyme, and (4) the reactivation by pyridoxal 5'-phosphate and pyridoxamine 5'-phosphate after dissociation of the coenzyme. The mechanism of the reactivation by pyridoxamine 5'-phosphate is the most interesting problem opened by the present research.

Animals↗
PubMedDate not supplied

Activation and inhibition of rat liver L-threonine dehydrogenase.

We have studied some characteristics of mitochondrial rat liver L-threonine dehydrogenase during freezing: the enzyme shows a net increase in activity and a "shift" in the pH optimum after storage at -20 degrees C of mitochondrial preparations. An unknown effector, which inhibited significantly the dehydrogenase activity, was isolated from the same preparations kept for 7-10 days at -20 degrees C. Some properties of the inhibitor have been determined.

Alcohol Oxidoreductases↗
PubMedDate not supplied

Primary structure of rat liver L-threonine deaminase.

The primary structure of rat liver L-threonine deaminase has been studied utilizing a highly purified preparation (S.A. = 940 U/mg protein) obtained from Wistar male rats. These data have been compared with the predicted sequences obtained by other Authors, showing a considerable concordance with the Noda's prediction and difference with the Ogawa's results. The FAB-MS analysis has demonstrated the presence of an acetyl group as blocking agent on the N-terminal alanine.

Amino Acid Sequence↗
PubMedDate not supplied

Amino acid sequence around the pyridoxal 5'-phosphate binding site of rat liver L-threonine deaminase.

Rat liver L-threonine deaminase is a pyridoxal 5'-phosphate dependent enzyme. In the present study we have studied the amino acid sequence composition of the peptide surrounding the coenzyme binding lysine at the active site of the native enzyme. We have also examined the homology between this peptide and the analogue forms of L-threonine deaminase from different sources.

Amino Acid Sequence↗
PubMedDate not supplied

Synthesis and NMR properties of 2-(4-pyridyl) thiazolidine-4-carboxylic acids.

Various thiazolidine derivatives, obtained through condensation between pyridoxal or pyridoxal-5'-phosphate with several aminothiols, have been obtained and examined for their NMR spectra. For the compounds tested, we demonstrated the presence in solution of the two diasteroisomeric thiazolidines, A and C, which differ for the configuration at C2, and are interconverted via the open chain Schiff's base, with different rates, depending on the pH. The possibility that, when aminothiols react with PLP bound to the enzyme, only one of the two diasteroisomers may be formed, and the biological role of such derivatives is discussed.

Cysteine↗
PubMedDate not supplied

Spinach threonine dehydratase. Inhibition by L-cysteine and D-cysteine.

L-threonine deaminase from spinach is inhibited by D- and L-cysteine. The inhibition patterns by D-cysteine and by L-cysteine are non-competitive. The value of Ki for D-cysteine and L-cysteine is of the same order of magnitude. Inhibitions by L-isoleucine and L-cysteine are additional. These results indicate that inhibition by L-cysteine occurs on a site of enzyme which is different from the binding site for L-isoleucine and L-valine. Probably L-cysteine and D-cysteine form the thiazolidinic ring with a PLP mole. Which is not costituent of the active site, but located in a different region.

Binding Sites↗
PubMedDate not supplied

[Primary suppurated splenic cysts. A case report].

The authors describe a case of an epidermoidal cyst of the spleen, which they were able to observe in an emergency case, due to suppuration of the cyst. Primary cysts of the spleen represent a rare dysontegenetic pathological condition which is, for this reason, often underestimated. The general clinical summary is related here, with particular reference to supporative complications, which cause problema of differential diagnosis with patients suffering from abscess of the spleen. The diagnosis can be made as a result of standard X-ray procedures and computed tomography and above all, following a simple scan. The treatment recommended in this case is an open splenectomy, in order to check the allarming clinical symptoms of the patient, which can deteriorate. The use of laparoscopical techniques or trans-cutaneous draining is reserved for salected cases.

Adult↗
PubMedDate not supplied

Purification and properties of rat liver L-threonine deaminase.

Rat liver threonine deaminase has been partially purified. The enzyme deaminates L-threonine and L-serine, is not affected by isoleucine, nor by AMP and ADP. L-cysteine and analogues are inhibitors of threonine deaminase and it is very likely that the inhibition is due to the formation of a thiazolidine ring with PLP bound to the enzyme. However, the simple formation of this ring does seem to explain completely the different degree and type of inhibition shown by L-cysteine and analogues. The hypothesis that the different behaviour of L- and D-cysteine is due also to interactions independent of the formation of thiazolidinic ring is discussed.

Animals↗