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Titolo:
How does hexachlorobenzene treatment affect liver uroporphyrinogen decarboxylase?
Autore:
Chaufan, G; de Molina, MDR; de Viale, LCS;
Indirizzi:
Univ Buenos Aires, Fac Ciencias Exactas & Nat, Dept Quim Biol, Lab Porfirias Expt & Metab Hemo, Buenos Aires, DF, Argentina Univ Buenos Aires BuenosAires DF Argentina Buenos Aires, DF, Argentina
Titolo Testata:
INTERNATIONAL JOURNAL OF BIOCHEMISTRY & CELL BIOLOGY
fascicolo: 6, volume: 33, anno: 2001,
pagine: 621 - 630
SICI:
1357-2725(200106)33:6<621:HDHTAL>2.0.ZU;2-E
Fonte:
ISI
Lingua:
ENG
Soggetto:
PORPHYRINOGEN CARBOXY-LYASE; HUMAN-ERYTHROCYTES; CUTANEA-TARDA; PURIFICATION; RAT; INHIBITION; OXIDATION; ENZYME; BIOSYNTHESIS; SITE(S);
Keywords:
active site; antigenic determinants; hexachlorobenzene; porphyria cutanea tarda; uroporphyrinogen decarboxylase;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
31
Recensione:
Indirizzi per estratti:
Indirizzo: de Viale, LCS OHiggins 4332, RA-1429 Buenos Aires, DF, Argentina OHiggins4332 Buenos Aires DF Argentina RA-1429 , Argentina
Citazione:
G. Chaufan et al., "How does hexachlorobenzene treatment affect liver uroporphyrinogen decarboxylase?", INT J BIO C, 33(6), 2001, pp. 621-630

Abstract

The aims of the present work were: (1) to investigate whether the strong decrease of liver uroporphyrinogen decarboxylase (UroD) activity observed inexperimental porphyria cutanea tarda is due to alteration of the enzymaticprotein and (2) to improve the knowledge about the normal liver enzyme. With these purposes, several physicochemical studies for enzymatic characterization were carried out comparatively on the 12-fold purified liver enzyme of both normal and hexachlorobenzene porphyric rat. The study shows that the enzyme from porphyric rats has a higher activation energy, lower reactivity index and lower optimum pH than the normal one. In addition, it did not reach the V-max at any of the substrate concentrations assayed (up to 28 muM uroporphyrinogen III), while the: normal enzyme reached the plateau around 14 muM. The porphyric enzyme appears to be more protected than the normalagainst the inhibitory action of several metals, particularly Cu2+ and Pb2, and against thermal inactivation. Zn2+ did not affect enzymatic activity, whereas Cu2+, Hg2+, Fe2+, Pb2+, and Cd2+ lowered the activities: of both normal and porphyric enzyme in a dose-related way. It was also observed that the larger the atomic radius in its hydrated state, the lower the effect of the metal. Neither glutathione nor dithiothreitol significantly altered enzymatic activity in the range of concentrations assayed. beta -Mercaptoethanol had diverse effects, as regards both the concentration assayed and the enzymatic sample used. Assays with cystine showed a dual behaviour of both normal and porphyric enzymatic activity. Western blots for both preparations revealed a single band (65 kDa) with a similar intensity. This study show that hexachlorobenzene treatment modifies the physicochemical propel ties of liver UroD leading to a sharp decrease of its activity, without affecting its antigenic reactivity probably as a consequence of changes at the conformational level promoted by the binding of its reported inhibitor. (C) 2001 Elsevier Science Ltd. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 03/04/20 alle ore 08:02:55