Site selectivity in the binding of inorganic anions to serum transferrin.
Site selectivity in the binding of inorganic anions to serum transferrin.
复制标题
无机阴离子与血清转铁蛋白结合的位点选择性。
DOI：
10.1016/0162-0134(90)84011-d
复制
发表时间：
1990
影响因子：
3.9
通讯作者：
Mohamed-Hani,N
中科院分区：
文献类型：
--
作者：
Harris,WR;Nesset-Tollefson,D;Stenback,JZ;Mohamed-Hani,N
Equilibrium constants for the sequential binding of two anions at the specific metal-binding sites of apotransferrin have been measured by difference ultraviolet spectroscopy in 0.1 M N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid (Hepes) at pH 7.4 25°C. Log K1values for phosphate, phosphite, sulfate, and arsenate fall in the narrow range of 3.5–4.0, while the log K1for bicarbonate is 2.73. No binding is observed for nitrate, perchlorate, or borate. A dinegative charge appears to be the most important criterion for anion binding. Equilibrium constants have also been measured for binding of anions to both forms of mono(ferric)transferrin. There appears to be a very small site selectivity (0.2 to 0.4 log units) for phosphate, arsenate, and phosphite that favors binding to the N-terminal site, but there is no detectable selectivity for binding of sulfate or bicarbonate. Comparison of the binding affinities and anion selectivity with literature data on anion-binding to protonated macrocyles and cryptates strongly supports the existence of specific anion-binding sites on the protein. Binding constants were also measured in 0.01 M Hepes. The anionic sulfonate group of the buffer appears to have a small effect on anion binding.
