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C Foppoli

Publications and source records attributed to C Foppoli.

At least 37 records · Page 2Linked to original sources
PubMed1988

Oxidative deamination of Se-(1-carboxyethyl)-,Se-(1-carboxypropyl)- and Se-(2-carboxyethyl)-selenocysteine by snake venom L-aminoacid oxidase.

Details are reported for the synthesis of Se-(1-carboxyethyl)-selenocysteine (1-CESeC), Se-(1-carboxypropyl)-selenocysteine (1-CPSeC) and Se-(2-carboxyethyl)-selenocysteine (2-CESeC). They can be obtained in pure cristalline form with good yield. Some chromatographic properties, useful for their identification, are described. The three aminoacids are good substrates for snake venom L-aminoacid oxidase, giving the corresponding alpha-ketoacids as reaction products.

Amino Acid Oxidoreductases↗
PubMed1987

Intracellular transport of thialysine and selenalysine in CHO cells.

The intracellular transport of thialysine and selenalysine in CHO cells has been studied. Data have been obtained indicating that the two lysine analogs can be transported by both the cationic aminoacid transport system and by the L transport system. The affinity of the cationic aminoacid transport system is similar for the two lysine analogs but lower than that for lysine and the affinity of the L transport system for the two lysine analogs is lower than that for leucine.

Amino Acids↗
PubMed1986

Transamination of L-cystathionine and related compounds by a bovine liver enzyme. Possible identification with glutamine transaminase.

A transaminase which catalyses the monodeamination of L-cystathionine was purified 1100-fold with a yield of 15% from bovine liver. The monoketoderivative of cystathionine spontaneously produces the cyclic ketimine. Other sulfur-containing amino acids related to cystathionine such as cystine, lanthionine and aminoethylcysteine were also substrates for the enzyme. The relative molecular mass of the enzyme was determined to be 94 000 with a probable dimeric structure formed of identical subunits. The isoelectric point of the enzyme was at pH 5.0 and the maximal enzymatic activity was found at pH 9.0--9.2. Kinetic parameters for cystathionine and for the other sulfur amino acids as well as for some alpha-keto acids were also determined. Among the natural amino acids tested, glutamine, methionine and histidine were the best amino donors. The enzyme exhibited maximal activity toward phenylpyruvate and alpha-keto-gamma-methiolbutyrate as amino acceptors. The broad specificity of the enzyme leads us to infer that the cystathionine transaminase is very similar or identical to glutamine transaminase.

Amino Acids↗
PubMed1986

Isolation and properties of a thialysine-resistant clone of CHO cells.

A variant clone of Chinese hamster ovary (CHO) cells resistant to thialysine has been isolated. It maintains the phenotypic properties even after 250 generations in medium without thialysine. Growth rate, cell viability and protein synthesis rate of the variant are much less affected by thialysine than the parental strain. In both the parental strain and the variant, thialysine acts in competition with lysine as indicated by the fact that all thialysine effects can be completely reversed by lysine.

Animals↗
PubMed1986

Effects of selenalysine on CHO cells.

Selenalysine, the lysine isolog with the 4-methylene group substituted by a Selenium atom, inhibits growth rate and plating efficiency of Chinese Hamster Ovary (CHO) cells. It does not affect DNA and RNA synthesis, but inhibits protein synthesis. Cells grown in the presence of selenalysine show a reduced viability and an increased cell volume. Almost all the effects of selenalysine on CHO cells can be reversed by lysine, thus indicating that selenalysine acts mainly in competition with lysine by impairing its utilization.

Animals↗
PubMed1986

Effects of selenalysine on thialysine resistant CHO cells.

A thialisyne resistant variant clone of CHO cells also shows a lower sensitivity to selenasyne, the lysine analog containing selenium. Growth rate, cell viability and protein synthesis rate are less affected by selenasyne in the variant compared to the parental strain. Data are reported showing that during cellular growth of either strain some toxic derivatives of selenasyne are produced and accumulated in the culture medium even in the presence of excess lysine.

Animals↗
PubMed1985

Effects of thialysine on CHO cells growth.

Thialysine, the lysine isolog with the 4-methylene group substituted by a sulfur atom, inhibits the growth rate and plating efficiency of Chinese Hamster Ovary (CHO) cells. The inhibition can be reversed by lysine, when added to the culture medium together with thialysine or shortly after; to have a complete reversion a lysine concentration five times that of thialysine is necessary. Cells grown in the presence of thialysine show a decreased viability and an increased volume. Thialysine inhibits protein synthesis, while it does not affect DNA and RNA synthesis. Protein synthesis inhibition can be reversed by lysine. Overall the results obtained indicate that thialysine affects cellular functions by impairing lysine utilization.

Animals↗
PubMed1983

Left ventricular mass and function before and after antihypertensive treatment.

We have studied the effect of blood pressure control upon left ventricular mass and function. Twenty hypertensive patients without clinical or electrocardiographic signs of cardiac involvement were given sequentially: placebo for two weeks; captopril (250 mg/day) for eight weeks; and captopril (125 mg/day), alone or combined with chlorthalidone (25 mg/day), for eight weeks. M-mode echocardiography was performed at the end of placebo period, after eight and after 16 weeks active treatment. Blood pressure was significantly reduced (p less than 0.01) by therapy, the maximum decrease being observed at the end of the study. Similarly, interventricular septal thickness, posterior wall thickness and left ventricular mass index showed a significant reduction (P less than 0.01 at the eighth and P less than 0.001 at the 16th week), while no changes were detected in left ventricular function. Furthermore, both wall stress index at end-diastole and end-systolic stress were significantly lowered by treatment (at the 16th week P less than 0.01 and P less than 0.001, respectively). Baseline systolic blood pressure was inversely correlated with the ratio of the left ventricular radius to posterior wall thickness (r = -0.97, P less than 0.001) but no relation was found between post-treatment fall in either systolic or diastolic blood pressure and left ventricular mass index. After treatment more patients showed normal left ventricular wall thickness in relation to systolic blood pressure. We conclude that in uncomplicated hypertensive patients captopril, either alone or combined with chlorthalidone, can reverse left ventricular hypertrophy by decreasing both septal and posterior wall thickness.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1982

Thialysine utilization by E. coli and its effects on cell growth.

Thialysine can be utilized for growth by a wild type K12 strain of E. coli. It is incorporated into proteins in substitution and in competition with lysine; up to 17% of protein lysine can be substituted by thialysine. Nevertheless the presence of thialysine in the culture medium gives rise to an inhibition of cell growth rate. This effect has been correlated to the inhibition of protein synthesis rate by thialysine and to the extent of protein lysine substitution by the analog. On the other hand this substitution does not affect cell viability.

Bacterial Proteins↗
PubMed1982

Selenalysine utilization for growth and protein synthesis by a lysine requiring E. coli mutant.

Selenalysine can be utilized in substitution of lysine by a lysine requiring E. coli mutant. The presence of some lysine in the culture medium is necessary to allow selenalysine utilization for growth; in the presence of an excess of lysine, selenalysine is not utilized. When utilized, selenalysine gives rise to an increase of final growth. However, it shows some toxic effects as demonstrated by the decrease of both growth rate and cell viability. Selenalysine is incorporated into proteins in substitution of lysine. Up to a maximum of 50% of total protein lysine can be substituted. The decrease of cell viability is correlated with the extent of lysine substitution.

Cell Division↗
PubMedDate not supplied

Studies on recognition of selenahomolysine by aminoacid transport systems and aminocyl-tRNA synthetase.

In E. coli, Se-3 aminopropylselenocysteine or selenahomolysine (SeHL) does not affect intracellular lysine transport, i.e. it cannot bind E. coli lysine transport systems. In CHO cells it inhibits cationic aminoacid transport system, but only in the presence of Na+, this indicating that it behaves like polar neutral aminoacids. On the other hand, it poorly affects leucine transport both in the presence and in the absence of Na+. SeHL is not activated by aminoacyl-tRNA synthetase preparations from bacterial and mammalian sources, thus it cannot be utilized for protein synthesis.

Amino Acids↗
PubMedDate not supplied

On the product of the reaction between cysteamine and 3-bromopyruvate.

Some properties of TZCA, the addition compounds of cysteamine and 3-bromopyruvate, have been investigated. From the behaviour of the UV absorption spectra in acidic and alkaline solutions in the presence or absence of oxygen, it was shown that the instability of TZCA was imputable to an oxidative degradation. It was further shown that TZCA undergoes in alkali spontaneous oxidative decarboxylation, and that the arising product may be hydrolyzed to cystamine and glyoxylic acid. Some chemical reactions and the paper chromatographic behaviour of TZCA are reported. It was shown that TZCA, despite its great instability, may be the reactions described, and thus differentiated from other adducts of bromopyruvate and different aminothiols.

Chemical Phenomena↗
PubMedDate not supplied

Oxidative deamination of S-(1-carboxyethyl)-L-cysteine and S-(1-carboxypropyl)-L-cysteine by L-aminoacid oxidase.

S-(1-carboxyethyl)-L-cysteine (1-CEC) and S-(1-carboxypropyl)-L-cysteine (1-CPC) are oxidatively deaminated by L-aminoacid oxidase with consumption of half a mole of oxygen per mole of substrate in the presence of catalase. This reaction gives rise to the corresponding alpha-ketoacids, identified by some chemical and chromatographic tests and by comparison with synthetic compounds. It has been possible, therefore, to demonstrate that S-(1-carboxyethyl)-thiopvruvic acid (1-CETP) and S-(1-carboxypropyl)-thiopvruvic acid (1-CPTP) are the main products of oxidative deamination of 1-CEC and 1-CPC.

Amino Acid Oxidoreductases↗
PubMedDate not supplied

Synthesis and chromatographic properties of S-(1-carboxyethyl)-L-cysteine and S-(1-carboxypropyl)-L-cysteine.

Details are reported for the synthesis of S-(1-carboxyethyl)-L-cysteine (1-CEC) and S-(1-carboxypropyl)-L-cysteine (1-CPC) from cysteine and 2-bromopropionic acid or 2-bromobutyric acid, respectively. Some analytical data and the behaviour of these two compounds on paper and ion-exchange chromatography are also reported, which allow their identification.

Amino Acid Oxidoreductases↗
PubMedDate not supplied

Oxidative deamination of thialysine by snake venom L-aminoacid oxidase.

Thialysine is oxidatively deaminated by snake venom L-aminoacid oxidase at alkaline pH. The oxygen consumption curves show a characteristic diphasic course: the quick uptake of half a mole of oxygen per mole of substrate, in aggreement with a typical oxidative deamination, is followed by a slow extra oxygen consumption. The first product of the reaction is the corresponding alpha-oxo-epsilon-amino acid, which spontaneously cyclizes to the internal Schiff base 5-6-dihydro-delta 3,1,4-thiazin-3-carboxylic acid (TZCA). This latter has been identified by its UV absorption spectrum, by some chemical reactions, by paper chromatography, and by the production of cystamine and glyoxylic acid after prolonged oxidation of thialysine followed by acid hydrolysis. The possibility of an alpha-beta elimination reaction giving rise to cysteamine from thialysine, coupled to the oxidative deamination, has been excluded.

Amino Acid Oxidoreductases↗
PubMedDate not supplied

Oxidation of D-thiazolidine-4-carboxylic acid by hog kidney D-aminoacid oxidase.

D-Thiazolidine-4-carboxylic acid is a good substrate for hog kidney D-aminoacid oxidase. Data are presented showing that the only oxidation product is delta 3-thiazoline-4-carboxylic acid, which does not undergo further spontaneous degradation. Thus, the oxidation of D-thiazolidine-4-carboxylic acid by D-aminoacid oxidase differs considerably from the oxidation of its L-isomer catalyzed by rat liver mitochondria which gives as final product N-formylcystine, possibly through the intermediate delta 2-thiazoline-4-carboxylic acid.

Animals↗