USE OF NITRIC-OXIDE AS A PROBE FOR ASSESSING FORMATION OF ASYMMETRICAL HEMOGLOBIN HYBRIDS - ATTEMPTED COMPARISON BETWEEN ALPHA-NO-BETA-NO-ALPHA-DEOXY-BETA-DEOXY, ALPHA-2-NO-BETA-2-DEOXY, AND ALPHA-2-DEOXY-BETA-2-NO HYBRIDS

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  • 1 January 1978
    • journal article
    • research article
    • Vol. 253  (10) , 3602-3606
Abstract
Some nitrosyl Hb derivatives have different optical spectram according to the nature of their quaternary structure. This property was used to detect the presence of in asymmetrical hybrids .alpha.NO.beta.NO.alpha.''O2.beta.''O2 in a mixture of the 2 Hb, .alpha.2NO.beta.2NO and .alpha.2''O2.beta.''O2. When changes are made, by deoxygenation, in the conformation of the hybrid, there is a characteristic modification in the optical spectrum of the nitrosyl subunits. Quantitative analysis of this phenomenon shows that asymmetrical .alpha.NO.beta.NO.alpha.deoxy.beta.deoxy and symmetrical .alpha.2NO.beta.2deoxy hybrids have distinct properties. The structure-linked optical transition is different in rate and amplitude. It is faster and larger for the asymmetrical molecule. CO binding kinetics performed in absence of phosphate indicated that the allosteric equilibrium is more displaced in favor of the T state for .alpha.NO.beta.NO.alpha.deoxy.beta.deoxy by comparison with the symmetrical deoxygenated intermediates.