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Biomedical subjects

B Salvato

Publications and source records attributed to B Salvato.

At least 73 records · Page 4Linked to original sources
PubMed1981

Evidence for acetylated amino-terminal residues in hemocyanins.

The NH2 amino acid terminals of hemocyanin from Carcinus maenas determined by the cyanate and by the dansyl-chloride methods gave very low yields. This gave values for the molecular weight which were abnormally high compared to those determined by physical methods. Assuming that the NH2 terminals are acetylated, the number of acetyl groups (determined spectrofluorimetrically) accounts for all the amino sugars present in hemocyanin and for the NH2 terminals assuming that the molecular weight of the polypeptide chains was 25,000 daltons.

Amino Acid Sequence↗
PubMed1981

The role of the cysteinyl and one of the tryptophyl residues in the neurotoxic action of suberitine.

The selective photooxidation of the single cysteinyl residue and one of the 3 tryptophyl residues of suberitine has been performed by irradiation using crystal violet and proflavine respectively as photosensitizers. Crystal violet and the protein form a 1:1 complex with a consequent partial inhibition of the neurotoxic activity. The latter is completely abolished by specific photooxidation of cysteine which is probably involved in the active site of the protein. The modification of the tryptophyl residue induces a large loss of the activity as a consequence of a photoinduced extensive denaturation of suberitine.

Cysteine↗
PubMed1979

Time dependence of hematoporphyrin distribution in selected tissues of normal rats and in ascites hepatoma.

The distribution of hematoporphyrin was determined in normal rats and in rats bearing ascites hepatoma as a function of time after i.p. injection of 10-20 mg/kg of dye. In both cases, hematoporphyrin displayed a high affinity for the tumor cells. At 20 mg/kg, the maximum difference between the amount of hematoporphyrin accumulated in the tumor and in the liver was obtained at 12 h after injection (tumor/liver ratio = 28). Our results suggest that hematoporphyrin is almost exclusively metabolized in the liver and excreted via the biliary tract, whereas only minor amounts are metabolized in the tumor cells. Moreover, the binding between the porphyrin and tumor cells is competitive with serum protein binding.

Animals↗
PubMed1979

Hemocyanin of Octopus vulgaris. The molecular weight of the minimal functional subunit in 3 M urea.

In the presence of 3 M urea Octopus vulgaris (Mollusca) hemocyanin dissociates completely, giving a single functional component which reassociates in the original aggregate after removal of urea. The molecular weight of this subunit has been determined by gel filtration, by viscosity measurements, and by ultracentrifugation. The values obtrained with the different methods range from 247,000 to 262,000. Electron microscopy shows that the reassociation of the functional subunit after removal of urea is complete and gives the typical cylindrical structure of the native protein. This component is the minimal functional subunit which can be obtained from Octopus hemocyanin without splitting covalent bonds. It is suggested that this component is made by five protomers (50,000 daltons) containing one oxygen binding site each bound covalently through, perhaps, the carbohydrate moieties of the protein.

Animals↗
PubMed1979

The binding of 1-anilino-8-naphthalene sulfonate to the hemocyanin of Octopus vulgaris.

The binding of 1-anilino-8-naphthalene sulfonate (ansyl) to native and copper-free hemocyanin of Octopus vulgaris has been studied in different conditions by measuring the fluorescence properties of the probe in the presence of hemocyanin. Native hemocyanin, either in the oxygenated or in the deoxygenated state, does not bind ansyl. The binding of ansyl with apohemocyanin induces a strong increase (from 0.004 to 0.6 -- 0.7) of the quantum yield and a blue shift from 520 nm to 460 nm of the emission maximum indicating the presence of ansyl binding sites in the protein. Experimental evidence is reported that the binding occurs at the copper-binding site of the protein. The dissociation constants of the ansyl-hemocyanin complexes are equal to about 10(-4) M, i.e. they are of the same order of those obtained with other proteins. The number of binding sites (n) of apohemocyanin for ansyl depends on the conformational state of the protein and ranges from 0.15 -- 0.80 mol/mol protein (Mr 50,000), depending on pH, ionic strength, and urea concentration. A negative interaction between the ansyl binding sites has been suggested.

Anilino Naphthalenesulfonates↗