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Titolo:
Structure/function of C5 convertases of complement
Autore:
Rawal, N; Pangburn, MK;
Indirizzi:
Univ Texas Hlth Ctr, Dept Biochem, Tyler, TX 75708 USA Univ Texas Hlth Ctr Tyler TX USA 75708 Dept Biochem, Tyler, TX 75708 USA
Titolo Testata:
INTERNATIONAL IMMUNOPHARMACOLOGY
fascicolo: 3, volume: 1, anno: 2001,
pagine: 415 - 422
SICI:
1567-5769(200103)1:3<415:SOCCOC>2.0.ZU;2-0
Fonte:
ISI
Lingua:
ENG
Soggetto:
COBRA VENOM FACTOR; ALTERNATIVE-PATHWAY; CLASSICAL PATHWAY; FLUID PHASE; MONOCLONAL-ANTIBODY; SERINE PROTEASES; C3-C5 CONVERTASE; COMPONENT C5; ACTIVATION; SYSTEM;
Keywords:
C5; C5 convertase; C3 convertase; complement; alternative pathway;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
63
Recensione:
Indirizzi per estratti:
Indirizzo: Rawal, N Univ Texas Hlth Ctr, Dept Biochem, 11937 US Highway 271, Tyler, TX 75708 USA Univ Texas Hlth Ctr 11937 US Highway 271 Tyler TX USA 75708 8 USA
Citazione:
N. Rawal e M.K. Pangburn, "Structure/function of C5 convertases of complement", INT IMMUNO, 1(3), 2001, pp. 415-422

Abstract

C5 convertases are serine proteases that cleave both C3 and C5. Alternative pathway C3/C5 convertases formed with monomeric C3b (C3b,Bb) because of their weak interaction with C5 primarily cleave C3 thereby opsonizing the cell surface with C3b. In contrast, C3/C5 convertases formed with a high density of C3b/cell exhibit higher affinities for C5 as indicated by K-m valueswell below the physiological concentration of C5 in blood. These C3/C5 convertases bind C5 efficiently and cleave it at a velocity approaching V-max thereby switching the enzyme from C3 cleavage to production of the cytolytic C5b-9 complex. Studies of the structure of C3/C5 convertases have postulated that C4b-C3b and C3b-C3b dimers form high affinity C5 binding sites while indel studies have shown two binding sites in C5 for the convertase in addition to the C5 cleavage site. Together, these studies indicate that withincreasing deposition of C3b on the surface, C3b complexes are formed which through multivalent attachment bind the substrate C5 with higher affinities thereby converting the low affinity C3/C5 convertases to high affinity C5 convertases. The process underlying the formation of high affinity C5 convertases during complement activation is discussed. (C) 2001 Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 06/04/20 alle ore 21:42:48