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Biomedical subjects

L Pecci

Publications and source records attributed to L Pecci.

At least 37 records · Page 2Linked to original sources
PubMed1990

Detection of 2H-1,4-thiazine-5,6-dihydro-3-carboxylic acid (aminoethylcysteine ketimine) in the bovine brain.

2H-1,4-Thiazine-5,6-dihydro-3-carboxylic acid (trivial name: aminoethylcysteine ketimine) is a cyclic sulfur-containing imino acid detected in bovine brain extracts by means of three different procedures. Gas liquid chromatography of protein-free extracts of five bovine brains revealed the presence of this compound at concentrations ranging from 2 to 3 nmol/g wet weight of tissue. The enzymatic method based on the inhibition of D-amino acid oxidase activity by aminoethylcysteine ketimine together with an high-performance liquid chromatography procedure confirm the identification and quantitations obtained with gas liquid chromatography. The discovery of this compound structurally similar to pipecolic acid opens the question of its physiological role in the central nervous system.

Amino Acids, Sulfur↗
PubMed1990

Detection of cystathionine ketimine in bovine cerebellum.

A new sulfur-containing cyclic imino acid, cystathionine ketimine, has been detected in bovine cerebellum by gas chromatography, gas chromatography-mass spectrometry, and high pressure liquid chromatography procedures. Gas chromatography and gas-mass analyses are based on derivatization of endogenous cystathionine ketimine with diazomethane after a simple enrichment procedure. The high pressure liquid chromatography procedure takes advantage of the selective absorbance at 380 nm of the phenyl isothiocyanate-ketimine interaction product. The concentration of this new sulfur imino acid found in a pool of four bovine cerebella is approximately 0.5 nmol/g.

Animals↗
PubMed1988

Bovine brain ketimine reductase.

We report the purification from bovine brain of an NAD(P)H-dependent reductase which actively reduces a new class of cyclic unsaturated compounds, named ketimines. Ketimines arise from the transamination of some sulphur-containing amino acids, such as L-cystathionine, S-aminoethyl-L-cysteine and L-lanthionine. The enzyme also reduces delta 1-piperidine 2-carboxylate, the carbon analog of aminoethylcysteine ketimine. Some kinetic and molecular properties of this enzyme have been determined. Subcellular localization and regional brain distribution have also been studied. The ketimine reductase activity was found to be associated with the soluble fraction, and was located prevalently in the cerebellum and cerebral cortices. Cyclothionine and 1,4-thiomorpholine-3,5-dicarboxylic acid, the enzymatic reduction products of cystathionine ketimine and lanthionine ketimine, respectively, have been detected in bovine brain, thus suggesting a role of this enzyme in their biosynthesis.

Animals↗
PubMed1988

Detection of cystathionine and lanthionine ketimines in human urine.

A recently developed HPLC procedure for the determination of cystathionine ketimine (CK) and lanthionine ketimine (LK) has been applied to the detection of these compounds in human urine. The assay has taken advantage of the selective production of an absorbance at 380 nm, not seen with other amino acids, when the two ketimines are reacted with phenylisothiocyanate. Coelution with authentic phenylthiohydantoin derivatives of CK and LK and the identical absorption spectra establish the identity of the compounds found in the urine with the synthetic products. Quantitation of the two ketimines by HPLC indicates that the excretion of CK and LK is respectively 606 micrograms and 84 micrograms per g of creatinine as mean values of 10 healthy subjects of both sexes, 20-40 years old, in the early morning voided urine.

Adult↗
PubMed1987

Individual knowledge of emotions in asthmatic children.

Twenty male asthmatic children (ages 9-11) and their controls were interviewed regarding their concept of emotion using the interview format developed by Harris et al. (1981). The purpose of the study was to examine the asthmatic children's views on the nature and effects of happiness, anger and fear, together with strategies of self-control. The results indicate that healthy and asthmatic children have a different individual view of emotion. The most relevant finding concerns the different way in which healthy and asthmatic children consider fear: the most frequent view of fear in healthy children is similar to a behaviouristic model of emotion, while asthmatic children express a notion very similar to a cognitive model. Regarding anger, almost all healthy children believe themselves capable of exerting self-control whether on the inner mental components or on its outer expression, where a change of direction of mental processes is the only way asthmatic children see to modify their anger. The implications of these findings both for a description of asthmatic personality and therapy are outlined.

Anger↗
PubMed1987

Hexahydro-1,4-thiazepine-3,5-dicarboxylic acid and thiomorpholine-3,5-dicarboxylic acid are present in normal human urine.

Hexahydro-1,4-thiazepine-3,5-dicarboxylic acid and thiomorpholine-3,5-dicarboxylic acid, simply referred to as cyclothionine and TMDA, respectively, are two cyclic sulfur-containing imino acids detected in bovine brain. Human urine has been investigated to establish the occurrence of these imino acids as common constituents under normal conditions. The morning urine of healthy subjects has been analyzed for enrichment of these compounds by using an ion-exchange procedure. Gas/liquid chromatography of the final extracts revealed the presence of peaks coeluting with authentic cyclothionine and TMDA. The latter compound eluted very close to an unknown sulfur-containing compound. A resolved peak of TMDA has been obtained by high-performance liquid chromatography of the final extracts derivatized with phenylisothiocyanate. Selected ion monitoring with multiple-ion detection applied to the compounds separated by gas chromatography revealed the presence of the respective molecular ions and of the decarboxylated fragments, thus confirming the identification of cyclothionine and TMDA in human urine.

Adult↗
PubMed1985

Gas-chromatographic mass-spectrometric detection of 1,4-hexahydrothiazepine-3,5-dicarboxylic acid (cyclothionine) in bovine brain.

Cystathionine has been reported to undergo enzymatic changes leading to the formation of seven membered cyclic products (Ricci, G., Santoro, L., Achilli, M., Matarese, R. M., Nardini, M., and Cavallini, D. (1983) J. Biol. Chem. 258, 10511-10517; Cavallini, D., Costa, M., Pensa, B., and Coccia, R. (1985) Biochem. Int. 10, 641-646). Gas-chromatographic and mass-spectrometric evidence reported in this paper indicates that the cyclic derivative of cystathionine, 1,4-hexahydrothiazepine-3,5-dicarboxylic acid, here simply named cyclothionine, is a normal component of bovine brain. This finding together with the detection of the same compound in the urine of cystathioninuric patients (Kodama, H., Sasaki, K., Mikasa, H., Cavallini, D., and Ricci, G. (1984) J. Chromatogr. 311, 183-188) supports the conclusion that cystathionine, apart from its role in trans-sulfuration, is converted also into cyclic compounds whose biochemical significance is as yet unknown.

Animals↗
PubMed1985

1,4-Thiomorpholine-3,5-dicarboxylic acid, a novel cyclic imino acid detected in bovine brain.

Gas-liquid chromatography of enriched bovine brain extract revealed the occurrence of several sulfur-containing compounds. By co-chromatography with authentic product and by mass-spectrometric analysis, one of these compounds has been identified as 1,4-thiomorpholine-3,5-dicarboxylic acid (TMDA). The possible derivation of TMDA from lanthionine is discussed. This represents the second S-containing cyclic amino acid so far discovered in a mammalian brain whose physiological significance has not yet been explored.

Animals↗
PubMed1983

gamma-Carboxyglutamic acid content in human kidney and placenta.

The presence of gamma-carboxyglutamate-containing proteins in human placenta and kidney has been examined. For the detection of these proteins gamma-carboxyglutamate content of alkaline hydrolysates of tissue homogenates has been determined. gamma-Carboxyglutamic acid was identified by amino acid analysis of alkaline and acid hydrolysates. In kidney a gamma-carboxyglutamate content of 4 nmol/mg of protein has been found, however in placenta this amino acid was undetectable (less than 0.1 nmol/mg of protein).

1-Carboxyglutamic Acid↗
PubMed1981

Multiple forms of bovine liver rhodanese.

The heterogeneity of crystalline rhodanese from bovine liver has been studied. The enzyme was separated by preparative disc electrophoresis into four stable forms designated I(3.5%), II(17.0%), III(62.0%) and IV(17.5%). All these components have the same molecular weight of about 35,000 both in native and denaturing conditions. No differences in the primary structure have been detected in amino acid composition and by peptide mapping. Although the isolated forms show similar values of specific activity, except form I, their content of transferable sulfur is different. The enzyme-sulfur complexes of the four components have slightly different circular dichroism spectra in the near ultraviolet, though their spectra in the sulfur-free state are identical. We conclude that these forms are conformational isomers originated from form IV which is predominant in the mitochondrial extract of liver cells.

Animals↗
PubMed1980

Cyanylation of rhodanese by 2-nitro-5-thiocyanobenzoic acid.

Cyanylation of rhodanese (thiosulfate:cyanide sulfurtransferase, EC 2.8.1.1) with a nearly stoichiometric amount of 2-nitro-5-thiocyanobenzoic acid produces a modification of the essential sulfhydryl group. Different S-cyano derivatives are obtained with the enzyme intermediate bearing transferable sulfur bound as a persulfide group (sulfur-rhodanese: E-S-SH) and with the sulfur-free rhodanese (E-SH). The interaction of a neighboring sulfhydryl group splits thiocyanate from the sulfur-rhodanese derivative and cyanide from the sulfur-free rhodanese derivative. In both cases an intramolecular disulfide bond is formed. Iodoacetate is effective on the modified enzyme only after cyanide addition which splits the disulfide so that the essential sulfhydryl group can be alkylated.

Animals↗
PubMed1977

Selective reactivity of rhodanese sulfhydryl groups with 5,5'-dithio-bis(2-nitrobenzoic acid).

The reactivity of the sulfhydryl groups of sulfur-containing and sulfur-free rhodanese (thiosulfate : cyanide sulfurtransferase, EC 2.8.1.1) with 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNB) has been investigated. Only 0.6 sulfhydryl group of the sulfur-containing enzyme reacts with DTNB. After removal of sulfur from persulfide groups a further 0.6 sulfhydryl group (i.e. a total of 1.2) becomes accessible to the reagent. The resulting enzyme-thionitrobenzoate complex shows an absorption spectrum with a shoulder at 325 nm due to bound thionitrobenzoate. Both thiosulfate and cyanide remove thionitrobenzoate from the enzyme restoring its catalytic properties. The modified enzyme is protected from alkylation by iodoacetate until thionitrobenzoate is removed. The existence of a further sulfhydryl group close to the catalytic one is suggested.

Animals↗
PubMed1976

Reaction of rhodanese with dithiothreitol.

The reaction between bovine rhodanese (thiosulfate:cyanide sulfurtransferase, EC 2.8.1.1) and reduced dithiothreitol has been studied. This reagent, in the absence of thiosulfate, reduces the amount of sulfur carried by rhodanese with formation of sulfide and oxidized dithiothreitol: E-S-SH + reduced dithiothreitol replaced by E-SH + HS- + oxidized dithiothreitol, (E = enzyme). An inactivation was observed at high dithiothreitol/enzyme ratios or at very low enzyme concentrations. The inactivation was not observed in the presence of thiosulfate and can be reversed by cyanide or thiosulfate. A thiosulfate reduction activity of rhodanese was also found using dithiothreitol as reductant.

Animals↗
PubMed1975

Inactivation of rhodanese by pyridoxal 5'-phosphate.

Pyridoxal 5'-phosphate and other aromatic aldehydes inactivate rhodanese. The inactivation reaches higher extents if the enzyme is in the sulfur-free form. The identification of the reactive residue as an amino group has been made by spectrophotometric determination of the 5'-phosphorylated pyridoxyl derivative of the enzyme. The inactivation increases with pyridoxal 5'-phosphate concentration and can be partially removed by adding thiosulfate or valine. Prolonged dialysis against phosphate buffer also leads to the enzyme reactivation. The absorption spectra of the pyridoxal phosphate - rhodanese complex show a peak at 410 nm related to the Schiff base and a shoulder in the 330 nm region which is probably due to the reaction between pyridoxal 5'-phosphate and both the amino and thiol groups of the enzyme that appear reasonably close to each other. The relationship betweenloss of activity and pyridoxal 5'-phosphate binding to the enzyme shows that complete inactivation is achieved when four lysyl residues are linked to pyridoxal 5'-phosphate.

Animals↗
PubMed1975

Selenium binding to beef-kidney rhodanese.

The reaction of beef kidney rhodanese with selenosulfate was studied. The selenium-treated enzyme shows an absorption spectrum with a maximum at 375 nm attributable to a sulfoselenide group. This absorption is bleached by addition of cyanide. After cyanide treatment stoichiometric amount of selenocyanate can be found. The intrinsic fluorescence of rhodanese is quenched by addition of stoichiometric selenosulfate. This effect can be reversed by cyanide or sulfite but not by selenite or glutathione. By comparison with model complexes the selenium-rhodanese intermediate was identified as a cysteinyl-selenium derivative.

Animals↗