Physicochemical and functional properties of Perinereis cultrifera (Grübe) erythrocruorin.
Biochim Biophys Acta
; 494(1): 1-8, 1977 Sep 27.
Article
en En
| MEDLINE
| ID: mdl-20151
ABSTRACT
Perinereis erythrocruorin has the following physicochemical properties So20,w = 55S, corresponding to a molecular weight around 2.7-10(6); minimum molecular weight (on the basis of the heme content) 23 700 +/- 500; isoelectric point 5.1; alpha-helix content approximately 40%. At alkaline pH values in the oxygenated form the 55-S molecules dissociate into subunits with a weight average sedimentation coefficient of 3S, corresponding to a molecular weight approximately 35 000. Deoxygenation of partially dissociated samples promotes association of the 3-S subunits into a 9S component. The functional properties of Perinereis erythrocruorin are characterized by a low cooperativity in oxygen binding (n 1/2 = 1.5) at neutral pH. Cooperativity increases reversibly towards both the acid and alkaline pH range, irrespective of changes in molecular weight. This finding, taken together with the ultracentrifuge results, suggests that a subunit may represent the functional unit of the protein. The pH dependence of the oxygen affinity can be accounted for in terms of a single oxygen linked group with a pK of 8.
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Banco de datos:
MEDLINE
Asunto principal:
Eritrocruorinas
/
Hemoglobinas
Idioma:
En
Año:
1977
Tipo del documento:
Article