Functional Non-Equivalence of α and β Hemes in Human Hemoglobins

Ho, Chien; Lindstrom, Ted R.

doi:10.1007/978-1-4684-3222-0_5

Cited by 10 publications

(3 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, this is not in agreement with the relative change in intensities between the -18 ppm T3-heme peak and the -12 ppm a-heme peak upon oxygenation as shown in Fig. 3 and discussed in our previous publications (12)(13)(14). In the presence of P2-glycerate (Fig.…”

Section: Experimental Section Materialscontrasting

confidence: 63%

Proton nuclear magnetic resonance investigation of structural changes associated with cooperative oxygenation of human adult hemoglobin

Viggiano

1979

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

The structural changes associated with cooperative oxygenation of human adult hemoglobin as a function of oxygen saturation in aqueous media at neutral pH and at 25-270C have been investigated by high-resolution proton nuclear magnetic resonance spectroscopy at 250 and 360 MHz. By monitoring the intensities of two hyperfine shifted proton resonances (at about -12 and -18 ppm from H20) and two exchangeable proton resonances (at alut -6.4 and -9.4 ppm from H20) as a function of oxygenation, the amount of oxygen bound to the a and /B chains of a hemoglobin molecule can be determined and the relationship between tertiary and quaternary structural changes under a given set of experimental conditions can be investigated. These results suggest that: (i) in the absence of organic phosphates, there is no preferential 02 binding to the a or chains; (ii) Despite considerable biochemical and biophysical studies devoted to the hemoglobin (Hb) molecule, the detailed molecular mechanism for the cooperative oxygenation of Hb is not fully understood. For example, it has not been possible, as yet, to correlate quantitatively various structural changes during the oxygenation process with the energetics of the process. A successful solution of the Hb problem is important not only because it would allow us to understand the molecular mechanism of a respiratory transport process, but also because it may give insights into the action of other more complex systems on which metabolic regulation depends. For recent reviews on the structure-function relationship in Hb, refer to refs. 1-5.Comparing the atomic models of deoxyhemoglobin and oxyhemoglobin-like methemoglobin, Perutz (6) has proposed a stereochemical mechanism for the cooperative oxygenation of Hb. In its original form, his model emphasized the link between the cooperativity and the transition between the two quaternary structures (deoxy quaternary structure is symbolized residues as excellent markers to monitor both tertiary and quaternary structural changes of Hb upon oxygenation. By choosing appropriate human mutant hemoglobins as well as chemically modified hemoglobins and by making use of Perutz's atomic models of hemoglobin, we have assigned a number of proton resonances, obtained through high-resolution proton nuclear magnetic resonance (NMR) spectroscopy, to specific amino acid residues in the Hb molecule. Of special interest to this work are the following resonances: the hyperfine shifted proton resonances at about -18 and -12 ppm from H20 due to protons from the # and a heme, respectively (8, 9); the exchangeable proton resonance at about -9.4 ppm from H20 due to the intersubunit hydrogen bond between a42(C7) tyrosine and f399(G1) aspartic acid in the a1/32 subunit interface, a characteristic feature of the deoxy quaternary structure (2, 10); and the exchangeable proton resonance at about -6.4 ppm from H20 due to the intrasubunit hydrogen bond between ,B98(FG5) valine and 3145(HC2) tyrosine, an important feature in the deoxy tertiary structure (11). Hence, b...

show abstract

Section: Experimental Section Materialscontrasting

confidence: 63%

Proton nuclear magnetic resonance investigation of structural changes associated with cooperative oxygenation of human adult hemoglobin

Viggiano

1979

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The reduced intensity of the resonance at -14.8 ppm suggests that 02 or CO binds to the figure 7: Difference CD spectra of solutions deoxyhemoglobins without IHP minus solutions with IHP and of oxy-minus deoxyhemoglobin A: deoxyhemoglobin Kempsey (-), deoxyhemoglobin NES-des-Arg (--), oxyhemoglobin A minus deoxhemoglobin A(.....). ß chain in preference to the a chain as in deoxyhemoglobins Kempsey and Yakima (Ho and Lindstrom, 1972;. It should be noted that the paramagnetically shifted resonances of deoxyhemoglobin A in 0.08 m Bis-Tris at pD 9.0 are at -16.9, -11.6, and -7.6 ppm, similar to those of deoxyhemoglobin A at pH 7.0 and very different from those of des-Arg-deoxyhemoglobin at pD 9.0.…”

mentioning

confidence: 78%

Influence of globin structure on the state of the heme. I. Human deoxyhemoglobin

Perutz¹,

Ladner²,

Simon³

et al. 1974

Biochemistry

Self Cite

307

222

View full text Add to dashboard Cite

“…Nmr and spin-labeling techniques have been shown to be useful in the study of hemoglobin structure and function (Davis et al, 1969(Davis et al, ,1971; Lindstrom et al, 1972a,b; Lindstrom ; Ho and Lindstrom, 1972;Ho et al, 1970Ho et al, , 1973; Baldassare et al, 1970;Ogawa et a!., 1968; McConnell, 1971, 1972a,b;Ogata et al, 1972;Shulman, 1971,1972;Cassoly et al, 1971). Nmr spectra of the hyperfine (or contact) shifted proton resonances have shown that the a and 0 hemes in deoxyHb A are not structurally equivalent and under certain circumstances, nonequivalent in their ligand affinities (Davis et al, 1971;Lindstrom et al, 1971Lindstrom et al, , 1972a; Lindstrom ; Ho and Lindstrom, 1972). In some cases, these hyperfine shifted resonances are sensitive to changes in the quaternary structure of the hemoglobin molecule (Davis et al, 1971;Perutz et al, 1974).…”

mentioning

confidence: 99%

Nuclear magnetic resonance and spin-label studies of hemoglobin Kempsey

Tr¹,

Jj²,

Bunn³

et al. 1973

Biochemistry

Self Cite

View full text Add to dashboard Cite

Nuclear magnetic resonance and spin-label studies of Hb Kempsey indicate that the substitution of asparagine for aspartate at G 1(99)0 produces widespread structural changes. The structural differences as well as concomitant changes in the functional properties indicate that the * subunit interface has a profound influence on the heme groups as they bind ligands. Comparison of the hyperfine shifted nuclear magnetic resonance (nmr) spectra of deoxyHb A and deoxyHb Kempsey shows that the structure of both a and 0 hemes is altered. Similar comparison of the ring-current shifted proton resonances of HbCO A and HbCO Kempsey X xemoglobin Kempsey is a mutant human hemoglobin which produces erythrocytosis in individuals heterozygous for Hb A1 and Hb Kempsey (Reed et al., 1968). Hb Kempsey differs from Hb A by a single amino acid substitution in the «102 subunit interface where the aspartic acid at 099 is replaced by an asparagine residue (Reed et al., 1968).Normally in deoxyHb A, the carboxy group of the aspartate at G 1(99)0 forms a hydrogen bond with the phenolic hydroxyl group of the tyrosine at C7(42)a and this hydrogen bond is broken in the transformation to the liganded form of Hb A (Perutz and Ten Eyck, 1971). In deoxyHb Kempsey, this important intersubunit hydrogen bond cannot be formed and the deoxy quaternary structure is less stable (Morimoto et al., 1971). In fact, the crystals of deoxyHb Kempsey have been found to have oxy-like quaternary structure (Perutz et al., 1974). This quaternary structural change in Hb Kempsey is thought to be the cause of the increased oxygen affinity and reduced cooperativity. In 0.05 m bis-tris + 0.1 m NaCl at pH 7.2 and 20°, the partial pressure of oxygen necessary to saturate 50% of the hemes {pbo) in Hb Kempsey is only 0.25 Torr whereas the pbi) of Hb A under similar conditions t From the Department of Biophysics and Microbiology and the

show abstract

Functional Non-Equivalence of α and β Hemes in Human Hemoglobins

Cited by 10 publications

References 28 publications

Proton nuclear magnetic resonance investigation of structural changes associated with cooperative oxygenation of human adult hemoglobin

Proton nuclear magnetic resonance investigation of structural changes associated with cooperative oxygenation of human adult hemoglobin

Influence of globin structure on the state of the heme. I. Human deoxyhemoglobin

Nuclear magnetic resonance and spin-label studies of hemoglobin Kempsey

Contact Info

Product

Resources

About