EPR OF METHEMOGLOBIN FORMATION IN RED CELLS W/ UNSTABLE HEMOGLOBIN
EPR OF METHEMOGLOBIN FORMATION IN RED CELLS W/ UNSTABLE HEMOGLOBIN
批准号:
6121166
负责人:
ODED SHAKA
金额:
$2.73万
依托单位国家:
美国
项目类别:
财政年份:
1998
资助国家:
美国
项目状态:
已结题
起止时间:
1998-05-05 至 2000-04-30
中文摘要
从衣原体真配子体的叶绿体中提取的血红蛋白,
克隆并在E.杆菌 这种血红蛋白类似于几种
在B10位置具有tyr残基并且在E7位置具有glut,
据信这两者都参与了与结合O2的H键合
这导致了极慢的解离速率。 另一方面,在一项研究中,
衣原体血红蛋白是不寻常的,因为铁蛋白具有一个
高自旋到低自旋(六配位)跃迁pK为8.5,而
铁蛋白具有高自旋到低自旋(六配位)
转变pK为6.4。 这表明,低分子量的远端配体
亚铁和铁蛋白的自旋形式可能不同。
铁蛋白表现出单一的低自旋形式,g值为
2.52,2.31,1.86,因此各向异性类似于肌红蛋白
氢氧化 然而,17 O EPR和18 O共振拉曼研究未能
提供了氢氧化物配体的直接证据 光谱研究
B10 Tyr、E7 Gln和E10 Lys残基的远端突变体
至今未能鉴定出可能的氨基酸配体。 进一步
正在进行研究以鉴定远端配体,
了解不寻常的低自旋EPR谱。
英文摘要
A Hb from the chloroplast of Chlamydomonas eugametos has been
cloned andexpressed in E. coli. This Hb resembles several invetebrate
in having a tyr residue in the B10 and a glut in the E7 positions,
both of which are believed to participate in H-bonding to bound O2
that results in extremely slow off-rates. On the other hand,
Chlamydomonas Hb is unusual in that the ferrous protein has a
high-spin to low spin (six-coordinate) transition pK of 8.5, whereas
the ferric protein has a high-spin to low spin (six-coordinate)
transition pK of 6.4. This suggests that the distal ligand of the low
spin forms of the ferrous and the ferric proteins may be different.
The ferric protein exhibits a single low spin form with g values of
2.52, 2.31, 1.86, and thus an anisotropy similar to that of myoglobin
hydroxide. However, 17O EPR and 18O resonance Raman studies failed to
provide direct evidence for a hydroxide ligand. Spectroscopic studies
on the distal mutants of the B10 Tyr, E7 Gln, and the E10 Lys residues
have so far failed to identify a possible amino acid ligand. Further
studies are being conducted to identify the distal ligand and to
understand the unusual low spin EPR spectrum.
期刊论文(0)
专著(0)
科研奖励(0)
会议论文
EPR OF METHEMOGLOBIN FORMATION IN RED CELLS W/ UNSTABLE HEMOGLOBIN
-
批准号:6281735
-
项目类别:
-
资助金额:$3.74万
-
财政年份:1998
-
负责人:ODED SHAKA
-
依托单位:
海外基金