HBED、EHPG分子内氢键与光谱性质

在pH 7.4、0.1 mol·L-1 Hepes条件下,由Tb3+荧光测得Tb-EHPG条件稳定常数log K为13.95±0.13;EHPG与金属离子结合后分子内O…H-O型氢键断裂而导致荧光被淬灭；HBED与金属离子结合后分子内N…H-O型氢键断裂而导致荧光增强,荧光变化均与结合的金属离子的原子量成反比.由此总结了稀土离子与HBED,EHPG结合的规律.并用荧光方法推断了脱铁伴清蛋白N-,C-端结合部位酪氨酸残基的分子内氢键类型.

Spectral Study on the Intramolecular H-Bonds of HBED and EHPG

N,N’-ethylenebis2-(o-hydroxyphenolic)glycine](EHPG) N,N’-di(2-hydroxybenzyl) ethylenediamine-N,N’-diacetic acid(HBED) are two ligands which have the same molecular weight but have different structures.In 0.1 mol·L-1 N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid(Hepes) at pH 7.4,by measuring the fluorescence intensities at 545 nm of Tb3+,we get the conditional binding constants of Tb-EHPG log K=13.95±0.13.EHPG and HBED have different types of intramolecular H-bonds,so the effects of metals binding on their fluorescence are very different,the former’s is decrease while the latter’s is increase,but the same is that all fluorescence change is an inverse of metal ion’s atomic weight.In this paper,we obtain the regular patterns of lanthanide ions binding EHPG and HBED,and the intramolecular H-Bond types of apoovotransferrin in N-terminal and C-terminal binding site are inferred by fluorescence methods.