Enhanced Inhibition of Polymerization of Sickle Cell Hemoglobin in the Presence of Recombinant Mutants of Human Fetal Hemoglobin with Substitutions at Position 43 in the 
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- 作者：Ming F. Tam ; Jun Chen ; Tsuey-Chyi S. Tam ; Ching-Hsuan Tsai ; Tong-Jian Shen ; Virgil Simplaceanu ; Timothy N. Feinstein ; Doug Barrick ; and Chien Ho
- 刊名：Biochemistry
- 出版年：2005
- 出版时间：September 13, 2005
- 年：2005
- 卷：44
- 期：36
- 页码：12188 - 12195
- 全文大小：113K
- 年卷期：v.44,no.36(September 13, 2005)
- ISSN：1520-4995
文摘
Four recombinant mutants of human fetal hemoglobin [Hb F (
2
2)] with amino acidsubstitutions at the position 43 of the -chain, rHb (D43L), rHb (D43E), rHb (D43W), and rHb(D43R), have been expressed in our Escherichia coli expression system and used to investigate theirinhibitory effect on the polymerization of deoxygenated sickle cell hemoglobin (Hb S). Oxygen-bindingstudies show that rHb (D43E), rHb (D43W), and rHb (D43R) exhibit higher oxygen affinity thanhuman normal adult hemoglobin (Hb A), Hb F, or rHb (D43L), and all four rHbs are cooperative inbinding O2. Proton nuclear magnetic resonance (NMR) studies of these four rHbs indicate that the quaternaryand tertiary structures around the heme pockets are similar to those of Hb F in both deoxy (T) and liganded(R) states. Solution light-scattering experiments indicate that these mutants remain mostly tetrameric inthe liganded (R) state. In equimolar mixtures of Hb S and each of the four rHb mutants (D43L, D43E,D43R, and D43W), the solubility (Csat) of each of the pairs of Hbs is higher than that of a similarmixture of Hb S and Hb A, as measured by dextran-Csat experiments. Furthermore, the Csat values forHb S/rHb (D43L), Hb S/rHb (D43E), and Hb S/rHb (D43R) mixtures are substantially higher thanthat for Hb S/Hb F. The results suggest that these three mutants of Hb F are more effective than Hb F ininhibiting the polymerization of deoxy-Hb S in equimolar mixtures.
22)] with amino acidsubstitutions at the position 43 of the -chain, rHb (D43L), rHb (D43E), rHb (D43W), and rHb(D43R), have been expressed in our Escherichia coli expression system and used to investigate theirinhibitory effect on the polymerization of deoxygenated sickle cell hemoglobin (Hb S). Oxygen-bindingstudies show that rHb (D43E), rHb (D43W), and rHb (D43R) exhibit higher oxygen affinity thanhuman normal adult hemoglobin (Hb A), Hb F, or rHb (D43L), and all four rHbs are cooperative inbinding O2. Proton nuclear magnetic resonance (NMR) studies of these four rHbs indicate that the quaternaryand tertiary structures around the heme pockets are similar to those of Hb F in both deoxy (T) and liganded(R) states. Solution light-scattering experiments indicate that these mutants remain mostly tetrameric inthe liganded (R) state. In equimolar mixtures of Hb S and each of the four rHb mutants (D43L, D43E,D43R, and D43W), the solubility (Csat) of each of the pairs of Hbs is higher than that of a similarmixture of Hb S and Hb A, as measured by dextran-Csat experiments. Furthermore, the Csat values forHb S/rHb (D43L), Hb S/rHb (D43E), and Hb S/rHb (D43R) mixtures are substantially higher thanthat for Hb S/Hb F. The results suggest that these three mutants of Hb F are more effective than Hb F ininhibiting the polymerization of deoxy-Hb S in equimolar mixtures.