Use of nitric oxide as a probe for assessing the formation of asymmetrical hemoglobin hybrids. An attempted comparison between alphaNObetaNOalphadeoxybetadeoxy, alpha2NObeta2deoxy, and alpha2deoxybeta2NO hybrids.

Cassoly, Robert

doi:10.1016/s0021-9258(17)34844-5

Cited by 23 publications

(1 citation statement)

References 29 publications

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“…There is other evidence that the doubly liganded tetramer possesses special properties. Work with asymmetric Hb hybrids indicate two types of the doubly liganded tetramer exist, one R-like and one T-like (Cassoly, 1978). This is also evident in the cooperative free energy values for the doubly liganded forms (Smith & Ackers, 1985).…”

Section: Discussionmentioning

confidence: 95%

Testing the two-state model: anomalous effector binding to human hemoglobin

Marden¹,

Es²,

Qh³

1986

Biochemistry

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Three allosteric states are required to describe the relaxation of (carbon monoxy) hemoglobin following flash photolysis. Combined absorbance and fluorescence probes were used. The absorbance signals consist of a component corresponding to ligand recombination and a component for the R-T transition. The fluorescence of 8-hydroxy-1,3,6-pyrenetrisulfonate (HPT), an analogue of 2,3-diphosphoglycerate, shows rates and amplitudes correlated with the absorbance transients. Measurements were made at pII 6, 6.5, and 7.0 at CO partial pressures of 0.1 and 1 atm. The fractional photolysis was varied in each case to change the initial distribution of the R states. Data show an immediate absorbance change due to ligand dissociation, while the changes in the ligand isosbestic and the fluorescence signals occur with time constants of 80 microseconds (at pH 6.5). The signals then show a biphasic return to equilibrium, characteristic of the allosteric system. The measurements provide three independent probes of the kinetics of the substates of hemoglobin. Although the ligand binding data can be generally represented by a two-state model, the fluorescence data require T states with different affinities for HPT.

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Section: Discussionmentioning

confidence: 95%