Biomedical subjects
Publications and source records attributed to C De Marco.
Details are reported for the synthesis of DL-selenazolidine-4-carboxylic acid starting from DL-selenocystine and formaldehyde. Some chemical reactions and the paper and ion-exchange chromatographic behaviour of selenazolidine carboxylic acid in comparison with thiazolidine-4-carboxylic acid are described.
In the presence of pyridoxal phosphate selenahomolysine undergoes alpha-beta elimination with production of pyruvate, ammonia and selenohomocysteamine. If the reaction occurs in anaerobic conditions the coupling of pyridoxal phosphate with selenohomocysteamine in a tetrahydro-selenazine ring may be detected by the appearance of an absorption band at 320 nm. In the presence of air the autoxidation rate of selenohomocysteamine is too high to allow the detection of the selenazine derivative. The results obtained add to the previously reported ones indicating that selenium- and sulfur-containing aminoacids react in quite the same way in the non enzymic model studied.
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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.
Selenalysine, a lysine analog having the C4 methylene group substituted by a selenium atom, may be decarboxylated to selenolanthionamine by bacterial lysine decarboxylase. The kinetic parameters obtained studying comparatively the decarboxylation of lysine, thialysine and selenalysine showed that while the enzyme is more effective on lysine than on its two analogs, there are no great differences between the last two. These results indicate that the substrate specificity of lysine decarboxylase is greatly affected by the substitution of a carbon atom of the substrate molecule, but the presence of either sulfur or selenium as eteroatom is without appreciable effect on the binding of the lysine analogs to the enzyme. In other words either sulfur- or selenium-containing substrate analogs are acted upon in the same way by lysine decarboxylase.
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.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Details are reported for the synthesis of Se-carboxymethylselenohomocysteamine from selenohomocysteamine and monochloroacetic acid. Data on its behaviour on paper and ion-exchange chromatography are also reported, which allow its identification.
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Details are reported for the synthesis of 1,3-thiazane-2-carboxylic acid, or beta-homothiaproline, 3-Bromopropylamine is allowed to react with sodium thiosulfate to give S-sulfo-homocysteamine, which is then split in acidic medium to homocystamine. Homocystamine is reduced by a slight excess of dithioerythritol and allowed to react with sodium glyoxylate. beta-Homothiaproline is then isolated by ion exchange on Dowex 50 and finally obtained in pure crystalline form, with a fairly good yield. Some chemical and chromatographic properties of beta-homothiaproline, in comparison with gamma-homothiaproline (1,3-thiazane-4-carboxylic acid), beta-thiaproline (thiazolidine-2-carboxylic acid) and gamma-thiaproline (thiazolidine-4-carboxylic acid) are described.
CMSeC labeled with 14C in the carboxymethyl moiety was incubated with snake venom L-aminoacid oxidase. As the product of the reaction only one ketoacid was detected, which retained all the radioactivity of the oxidized substrate. This clearly shows that no breakdown of the C-Se bond of CMSeC occurs during its oxidation, and confirms previously reported data indicating that the ketoacid arising from CMSeC is CMSeP.
Details are reported for the preparation of the 2-aminoethyl, 3-aminopropyl sulfide from 3-bromopropylamine and 2-mercaptoethylamine. For this compound, the shorter name cystathionamine is proposed. The corresponding sulfoxide and sulfone have been also prepared. Some analytical data and chromatographic properties are reported. Preliminary results show that cystathionamine is a good substrate for the pig kidney diamineoxidase.
Details are reported for the synthesis of selenocystathionamine, the 2-aminoethyl, 3-aminopropyl selenide, NH2CH2CH2-Se-CH2CH2CH2NH2. Paper and ion exchange chromatographic behaviour of the compound has been investigated. By automated ion exchange chromatography on a sulfonated resin selenocystathionamine may be easily differentiated from cystathionamine, cystamine and selenocystamine. It has been shown that selenocystathionamine is oxidatively deaminated by pig kidney diamineoxidase. Preliminary data indicate that the first product of the reaction is a cyclized aminoaldehyde which then undergoes further degradation.
Selenocystamine is oxidatively deaminated by pig kidney diamineoxidase. The first product of the reaction is the corresponding cyclized aminoaldehyde, selenocystaldimine, which then undergoes further degradation. The oxidative deamination is thus the first step of a series of cyclic reactions which give rise to extensive cleavage of selenocystamine.