Comparison of histidine proton magnetic resonances of human carbonmonoxyhaemoglobin in different buffers

• Published in: Journal of molecular biology Vol. 186; no. 2; pp. 471 - 473
• Main Authors: Perutz, Max F., Gronenborn, Angela M., Clore, G.Marius, Shih, Daniel T.-b., Craescu, Constantin T.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 20.11.1985; Elsevier
• Subjects: Biological and medical sciences; Buffers; Carboxyhemoglobin; Fundamental and applied biological sciences. Psychology; Hemoglobins; Histidine; Humans; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; Molecular biophysics; Physico-chemical properties of biomolecules; Protons; Human; Hemoprotein; Histidine; Hemoglobin; Proton; NMR spectrometry; Carbon monoxide; Buffer solution; Complexes; Comparative study
• ISSN: 0022-2836; 1089-8638
• DOI: 10.1016/0022-2836(85)90119-6

We have recorded the C-2 proton resonances of the histidines of carbonmonoxyhaemoglobin A and of four abnormal human HbCOs † † Abbreviations used: Hb, deoxyhaemoglobin: HbCO. carbonmonoxyhaemoglobin. in different buffers and at different concentrations of haemoglobin. Resonance H assigned by Perutz et al. (1985) to His HC3(146)β, is present at both pH 7.30 and pH 6.90, but somewhat broadened when recorded in 5 to 10% HbCO A in 0.1 m-bis-Tris. The broadening disappears on tenfold dilution of the Hb with bis-Tris and the resonance then stands out sharply. Resonance H is absent at both Hb concentrations in HbCO Cowtown (His HC3(146)β → Leu). HbCO Fort de France (His CD3(45)α → Arg) in 0.1 m-bis-Tris of pH 6.90 has a spectrum similar to that of HbCO A. In the same buffer a resonance marked L by Russu et al. (1982) is absent from the spectrum of Hb Abbruzzo (His H21(143)β → Arg), whereas resonance H is present. Hb Barcelona contains an additional histidine in position FG 1(94)β; in 0.1 m-bis-Tris buffer of pH 6.90 its resonance is not resolved and resonance H is either shifted or broadened. The resonances of both histidines are resolved in phosphate buffer. At pH 6.90, spectra in 0–1 m-bis-Tris buffer are similar to those previously recorded in 0.2 m-HEPES. Addition of 0.1 m-KCl produces marked changes. Replacement of bis-Tris by 0.2 m-KCl + 0.2 m-phosphate gives rise to a different and much better resolved spectrum.