Hemocyanin in the hemolymph of the horseshoe crab, @entity10255 L., is a high-molecular-weight @entity920 protein which binds @entity26 cooperatively and shows a higher @entity26 affinity at pH 7 than at pH 9. Treatment with @entity1098 ( @entity11890 ) disaggregates the hemocyanin molecules and abolishes both the reverse Bohr effect and cooperative @entity26 binding. @entity2865 ions interact with the @entity1098 -treated material and, in the presence of saturating amounts of @entity1219 , a reverse Bohr effect is restored, but cooperativity is not. The @entity1098 -treated hemocyanin contains at least five electrophoretically distinct @entity17970 . These @entity17970 have similar molecular weights (about 66,000) but are functionally dissimilar. They have different @entity26 affinities and different responses to @entity2865 ions. The effect of @entity2865 ions on unfractionated hemocyanin is due to pH-dependent @entity2865 interactions with only two of the five @entity17970 components. The functional differences between the hemocyanin components may provide Limulus with a valuable respiratory flexibility in its interaction with the environment. The kinetics of @entity26 combination and dissociation for the various hemocyanin preparations show that variations in the rate of @entity26 dissociation are primarily responsible for the observed differences in @entity26 affinity. The rate of @entity26 dissociation varies 20-fold under conditions where the apparent rate of @entity26 combination shows less than a 2-fold variation. Cooperative interactions in the untreated hemocyanin are most obvious in the "off" reaction, which increases in rate as successive @entity26 molecules are released.

Functional differences in the multiple @entity17970 of the horseshoe crab, XXXX L.

@entity1219 :: ('CHEBI:26710', 'Chemical') :: ['NaCl'] @entity26 :: ('MESH:D010100', 'Chemical') :: ['oxygen'] @entity17970 :: ('MESH:D006433', 'Chemical') :: ['hemocyanins', 'hemocyanin'] @entity10255 :: ('6850', 'Species') :: ['Limulus polyphemus'] @entity11890 :: ('CHEBI:42191', 'Chemical') :: ['ethylenediaminetetra-acetate'] @entity920 :: ('MESH:D003300', 'Chemical') :: ['copper'] @entity2865 :: ('CHEBI:17996', 'Chemical') :: ['Chloride', 'chloride'] @entity1098 :: ('MESH:D004492', 'Chemical') :: ['EDTA']
@entity10255 :: (6850,Species) :: ['Limulus polyphemus']
