Hb Arta [beta 45 (CD4) Phe-->Cys]: a new unstable haemoglobin with reduced oxygen affinity in trans with beta-thalassaemia.
Br J Haematol
; 91(3): 595-601, 1995 Nov.
Article
en En
| MEDLINE
| ID: mdl-8555060
ABSTRACT
The interaction of rare Hb variants with beta(0)-thalassaemia results in a quasihomozygous state where the erythrocytes contain the variant as the only major adult Hb component. Such a situation is a unique model that enables functional studies even in the case of a neutral variant that could not be isolated from Hb A. We report here an unusual patient carrying Hb Arta, a novel Hb variant [beta 45 (CD4) Phe-->Cys], in trans with beta(0)-thalassaemia gene (beta(0) 39). The aminoacid substitution at the critical CD corner of this Hb molecular renders the molecule unstable. In addition, haem is displaced in a position that favours the deoxy (T) conformation of the variant, but less than in Hb Cheverly [beta 45 (CD4) Phe-->Ser], and results in a p50 of 43 mmHg (pH 7.4, 37 degrees C) in the red cells with preservation of cooperativity. Solution studies of the almost pure Hb Arta show a 50% decrease in oxygen affinity and normal cooperativity; the Bohr effect and the interaction with organic phosphates are similar to those of Hb A. Hb Arta retains both normal homo- and heterotropic effects allowing a well-preserved oxygen transport in vivo despite a mild anaemia.
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Banco de datos:
MEDLINE
Asunto principal:
Oxígeno
/
Hemoglobinas Anormales
/
Talasemia beta
Tipo de estudio:
Prognostic_studies
Límite:
Adult
/
Female
/
Humans
Idioma:
En
Año:
1995
Tipo del documento:
Article