Roselli C, Boussac A, Mattioli T A, Griffiths J A, el-Sayed M A
Section de Bioénergetique, Commissariat á l'Energie Atomique Saclay, Gif-sur-Yvette, France.
Proc Natl Acad Sci U S A. 1996 Dec 10;93(25):14333-7. doi: 10.1073/pnas.93.25.14333.
Near infrared Yb3+ vibronic sideband spectroscopy was used to characterize specific lanthanide binding sites in bacteriorhodopsin (bR) and retinal free bacteriorhodopsin (bO). The VSB spectra for deionized bO regenerated with a ratio of 1:1 and 2:1 ion to bO are identical. Application of a two-dimensional anti-correlation technique suggests that only a single Yb3+ site is observed. The Yb3+ binding site in bO is observed to consist of PO2- groups and carboxylic acid groups, both of which are bound in a bidentate manner. An additional contribution most likely arising from a phenolic group is also observed. This implies that the ligands for the observed single binding site are the lipid head groups and amino acid residues. The vibronic sidebands of Yb3+ in deionized bR regenerated at a ratio of 2:1 ion to bR are essentially identical to those in bO. The other high-affinity binding site is thus either not evident or its fluorescence is quenched. A discussion is given on the difference in binding of Ca2+ (or Mg2+) and lanthanides in phospholipid membrane proteins.
近红外Yb3+振动边带光谱被用于表征细菌视紫红质（bR）和无视网膜细菌视紫红质（bO）中特定的镧系元素结合位点。用离子与bO的比例为1:1和2:1再生的去离子bO的VSB光谱是相同的。二维反相关技术的应用表明只观察到一个单一的Yb3+位点。观察到bO中的Yb3+结合位点由PO2-基团和羧酸基团组成，两者均以双齿方式结合。还观察到最有可能来自酚基团的额外贡献。这意味着观察到的单一结合位点的配体是脂质头部基团和氨基酸残基。以离子与bR的比例为2:1再生的去离子bR中Yb3+的振动边带与bO中的基本相同。因此，另一个高亲和力结合位点要么不明显，要么其荧光被淬灭。文中讨论了Ca2+（或Mg2+）与镧系元素在磷脂膜蛋白中结合的差异。
