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152 results on '"GULLOTTI, M."'

9. Selectivity in the peroxidase catalyzed oxidation of phenolic sulfides

Author

De Riso, A, Gullotti, M, Casella, L, Monzani, E, Profumo, A, Gianelli, L, DE GIOIA, L, Gaiji, N, Colonna, S, Colonna, S., DE GIOIA, LUCA, De Riso, A, Gullotti, M, Casella, L, Monzani, E, Profumo, A, Gianelli, L, DE GIOIA, L, Gaiji, N, Colonna, S, Colonna, S., and DE GIOIA, LUCA

Abstract

The catalytic oxidation of ortho- and para-alkylthiophenols, carrying methyl or ethyl substituents at sulfur, by lactoperoxidase (LPO), horseradish peroxidase (HRP) or chloroperoxidase (CPO), in the presence of hydrogen peroxide, has been investigated. HPP and CPO are active toward these substrates, whereas LPO is only active with the ortho-substituted compounds. The enzymatic solutions containing ortho-alkylthiophenols develop an intense blue color (with optical absorptions near 400 and 600nm) that is attributed to the formation of relatively stable dimeric three-electron bonded complexes resulting from the association of enzyme-derived radical cations with the phenolic sulfide. The products of the enzymatic reactions by HRP and LPO are oligomers resulting from phenol oxidative coupling reactions and the sulfoxide, with minor amounts of oligomers containing mono or disulfoxide functionalities. With CPO the major product is always the sulfoxide, while phenol coupling products are formed in minor amounts. The selectivity exhibited by LPO toward 2- and 4-methylthiophenol has been investigated through binding experiments, NMR relaxation measurements of LPO-substrate complexes and docking calculations. The para-isomer binds much more strongly than the ortho-isomer to the enzymes. The stronger binding depends on the establishment of hydrogen bonding interactions with protein residues in the active site. (C) 2003 Elsevier Science B.V. All rights reserved.

Published
2003

24. STERIC AND SOLVENT EFFECTS IN OXYGEN UPTAKE BY SALICYLIDENEIMINATO COBALT(II) COMPLEXES

Author

Cariati, F, Fusi, A, Gullotti, M, Morazzoni, F, Pasini, A, Salghetti, F, Ugo, R, CARIATI, F, FUSI, A, GULLOTTI, M, MORAZZONI, FRANCA, PASINI, A, SALGHETTI,F, UGO, R., Cariati, F, Fusi, A, Gullotti, M, Morazzoni, F, Pasini, A, Salghetti, F, Ugo, R, CARIATI, F, FUSI, A, GULLOTTI, M, MORAZZONI, FRANCA, PASINI, A, SALGHETTI,F, and UGO, R.

Published
1971

25. Optically active complexes of Schiff bases. Part II. Complexes of cobalt(II) with tetradentate Schiff bases and their reactivity with oxygen

Author

Busetto, C, Cariati, F, Fusi, A, Gullotti, M, Morazzoni, F, Pasini, A, Ugo, R, Valenti, V, BUSETTO, C, CARIATI, F, FUSI, A, GULLOTTI, M, PASINI, A, UGO, R, VALENTI, V., MORAZZONI, FRANCA, Busetto, C, Cariati, F, Fusi, A, Gullotti, M, Morazzoni, F, Pasini, A, Ugo, R, Valenti, V, BUSETTO, C, CARIATI, F, FUSI, A, GULLOTTI, M, PASINI, A, UGO, R, VALENTI, V., and MORAZZONI, FRANCA

Abstract

Complexes of cobalt(II) with Schiff bases obtained by condensation of salicylaldehyde with substituted ethylenediamines have been synthesised together with five-co-ordinated pyridine adducts. E.s.r., electronic, and c.d. spectra and magnetic susceptibilities have been reported. Energy level schemes have been calculated by a ligand field approach in order to fit the magnetic properties and allow an assignment of the observed absorption bands. The reaction with oxygen has been studied and discussed in terms of both the electron configuration of the cobalt atom and the steric effects of substituents on the carbon atoms of the substituted ethylenediamines.

Published
1973

29. Azide-binding studies reveal type 3 copper heterogeneity in ascorbate oxidase from the green zucchini squash (Cucurbita pepo)

Author

Casella, L, Gullotti, M, Pallanza, G, Pintar, A, and Marchesini, A

Abstract

Titration of native ascorbate oxidase from green zucchini squash (Cucurbita pepo) with azide in 0.1 M-phosphate buffer, pH 6.8, exhibits a biphasic spectral behaviour. Binding of the anion with ‘high affinity’ (K greater than 5000 M-1) produces a broad increase of absorption in the 400-500 nm region (delta epsilon approximately 1000 M-1.cm-1) and c.d. activity in the 300-450 nm region, whereas azide binding with ‘low affinity’ (K approximately 100 M-1) is characterized by an intense absorption band at 420 nm (delta epsilon = 6000 M-1.cm-1), corresponding to negative c.d. activity and a decrease of absorption at 330 nm (delta epsilon = -2000 M-1.cm-1). The high-affinity binding involves a minor fraction of the protein containing Type 3 copper in the reduced state, and the spectral features of this azide adduct can be eliminated by treatment of the native enzyme with small amounts of H2O2, followed by dialysis before azide addition. As shown by e.s.r. spectroscopy, Type 2 copper is involved in both types of binding, its signal being converted into that of a species with small hyperfine splitting constant [12 mT (approximately 120 G)] in the case of the low-affinity azide adduct. The spectral similarities of the two types of azide adducts with the corresponding adducts formed by native laccase, which also exhibits Type 3 copper heterogeneity, are discussed.

Published
1988
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35. [Occult gastrointestinal hemorrhage. Description of a case with unusual clinical presentation]

Author

flavio bobbio, Mc, Bertoncelli, Catania E, Zaccala G, Gf, Portigliotti, Gullotti M, and Monteverde A

Subjects
Diagnosis, Differential, Male, Diverticulum, Humans, Jejunal Diseases, Gastrointestinal Hemorrhage, Aged
Abstract

Bleeding from small bowel is a quite rare event and often is a diagnostic challenge to physician and surgeon. We present a case of a patient with an acute massive haemorrhage due to jejunal diverticulosis and with an unusual clinical setting. The site of bleeding was localized by scan with radiotagged erythrocytes, but the diagnosis of jejunal diverticule was evident only at laparotomy. The patient underwent to surgical resection of the affected bowel (40 cm). Although jejunal diverticula are considered a rare source of gastrointestinal haemorrhage, we suggest that this disorder must be considered in all patients with occult gastrointestinal bleeding especially in the elderly.

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