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Titolo:
Properties of St I and St II, two isotoxins isolated from Stichodactyla helianthus: a comparison
Autore:
Martinez, D; Campos, AM; Pazos, F; Alvarez, C; Lanio, ME; Casallanovo, F; Schreier, S; Salinas, RK; Vergara, C; Lissi, E;
Indirizzi:
Univ Santiago, Dept Chem, Fac Chem & Biol, Santiago, Chile Univ Santiago Santiago Chile ept Chem, Fac Chem & Biol, Santiago, Chile Univ La Habana, Fac Biol, Havana, Cuba Univ La Habana Havana CubaUniv La Habana, Fac Biol, Havana, Cuba Univ Sao Paulo, Inst Chem, Sao Paulo, Brazil Univ Sao Paulo Sao Paulo Brazil Sao Paulo, Inst Chem, Sao Paulo, Brazil Univ Chile, Fac Sci, Santiago, Chile Univ Chile Santiago ChileUniv Chile, Fac Sci, Santiago, Chile
Titolo Testata:
TOXICON
fascicolo: 10, volume: 39, anno: 2001,
pagine: 1547 - 1560
SICI:
0041-0101(200110)39:10<1547:POSIAS>2.0.ZU;2-P
Fonte:
ISI
Lingua:
ENG
Soggetto:
SEA-ANEMONE STICHODACTYLA; STICHOLYSIN-II; SECONDARY STRUCTURE; HEMOLYTIC-ACTIVITY; MECHANISM; MEMBRANES; CYTOLYSIN; CONFORMATION; ERYTHROCYTES; RADICALS;
Keywords:
sticholysins; hemolytic activity; conformation; membrane binding;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
24
Recensione:
Indirizzi per estratti:
Indirizzo: Lissi, E Univ Santiago, Dept Chem, Fac Chem & Biol, Santiago, Chile Univ Santiago Santiago Chile Fac Chem & Biol, Santiago, Chile
Citazione:
D. Martinez et al., "Properties of St I and St II, two isotoxins isolated from Stichodactyla helianthus: a comparison", TOXICON, 39(10), 2001, pp. 1547-1560

Abstract

Sticholysins I and II are two highly hemolytic polypeptides purified from the Caribbean Sea anemone Stichodactyla helianthus. Their high sequence homology (93%) indicates that they correspond to isoforms of the same hemolysin. The spectroscopic measurements show a close similarity in the secondary structure content, conformation and stability of both toxins. Exposure of the toxins to high pHs (> 11), a free radical source (AAPH), urea or temperature produce permanent changes in the toxin that lead to a significant lossof HA. It is significant to note that this loss of hemolytic activity occurs when other indicators, probably with the only exception of near-UV CD spectra, barely detect changes in the protein structure. This emphasizes the sensitivity of the protein function to changes in the macromolecule conformation. The most noticeable difference between both toxins is the considerably higher activity of St II, both measured in terms of erythrocyte internalK+ exit or hemolysis; which is related to enthalpic factors. This difference is not due to an incomplete association of St I to the membrane. We consider then that the different pore forming capacity of both toxins in erythrocytes can be explained in terms of the difference in charge of the N-terminal fragment, than can considerably reduce the St I insertion rate in the membrane probably due to the negatively charged outer leaflet of the red blood cell, without a significant reduction of its capacity to bind to the cell membrane. This electrostatic effect, together with a slightly more relaxed structure in St II, could explain the higher pore forming capacity of St II in the red blood cell membrane. (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 19/01/20 alle ore 09:16:22