HB Rancho Mirage [β143(H21)HIS→ASP]; A Variant in the 2,3-DPG Binding Site Showing Normal Oxygen Affinity at Pewsioidgical pH
作者:
MooW. F.,
HineT. K.,
JoansonM. H.,
JueD. L.,
HollandS.,
GeorgeS.,
PiemA. M.,
MichalskiL. A.,
McDonaldM. J.,
期刊:
Hemoglobin
(Taylor Available online 1992)
卷期:
Volume 16,
issue 1-2
页码: 35-44
ISSN:0363-0269
年代: 1992
DOI:10.3109/03630269209005674
出版商: Taylor&Francis
数据来源: Taylor
摘要:
Hb Rancho Mirage was detected in a 17-year-old male in association with a mild anemia. Hemoglobin electrophoresis revealed the variant had a mobility between Hbs A and J on cellulose acetate (pH 8.6) and a mobility like Hb F on citrate agar (pH 6.4). A substitution of His→Asp was found at position 143 in theßchain, a residue that contributes to the anionic 2,3-DPG binding site in Hb. This variant exhibited normal oxygen affinity at physiologic pH and reduced affinity at alkaline pH. This suggested a subtle shift in the allosteric equilibrium due most likely to the introduction of a negative charge that stabilized the 2,3-DPG pocket. Both homotrophic (heme-heme) and heterotropic (2,3-DPG and protons) effects were reduced; this might be a consequence of an alteration in the carboxyl terminal region of theß-subunits. Although a His→Asp substitution would be considered to cause reasonable disruption of the 2,3-DPG and C-terminal conformation of theß- subunits, the properties of Hb Rancho Mirage suggest that, in fact, there appear to be no major perturbation of the critical C-terminal residues.
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