Determination of the solvent accessibility of specific aromatic residues in gamma-crystallin by photo-CIDNP NMR measurements.
Determination of the solvent accessibility of specific aromatic residues in gamma-crystallin by photo-CIDNP NMR measurements.
复制标题
通过光 CIDNP NMR 测量测定 γ-晶状体蛋白中特定芳香族残基的溶剂可及性。
DOI：
10.3109/02713688408997194
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发表时间：
1984
影响因子：
2
通讯作者：
R. Kaptein
中科院分区：
文献类型：
--
作者：
W. Garner;A. Spector;T. Schleich;R. Kaptein
利用5瓦氩激光激发（488nm）的3- n -羧甲基荧光黄素（flavin I）染料与该蛋白形成的环状自由基对相互作用所产生的核磁共振谱线的显著强度增强，测量了calf- γ II晶体蛋白在溶液（1mm）中某些芳香残基的表面或溶剂可及性。这种效应被称为光化学诱导的动态核极化（photocidnp）。“光”和“暗”核磁共振波谱在脉冲傅立叶变换模式下在布鲁克360兆赫仪器上交替扫描。减法得到的光- cidnp差分光谱包含极化残基的谱线。在黄素染料中，只有酪氨酸、组氨酸和色氨酸可以被极化。基于van der Waal接触半径，从原子坐标计算了这些残基各自的理论静态可及性，并为评价动态核磁共振光- cidnp结果和分配共振提供了依据。这些结果表明，当4种色氨酸残基被完全掩埋时，5种组氨酸中的His-113和His-14；15种酪氨酸中的tyr165和tyr62充分暴露可引起光- cidnp效应。这些结果证实并扩展了以前通过理论静电程序和FT-NMR测量获得的观察结果。
The surface or solvent accessibility of certain individual aromatic residues of calf-gamma II crystallin in solution (1 mM) were measured by the dramatic intensity enhancements of NMR lines generated by the interactions of cyclic radical pair formation of the 3-N-carboxymethyl lumiflavin (flavin I) dye excited (488nm) by an argon laser (5 watts) with the protein. This effect is called photo-chemically induced dynamic nuclear polarization: photo-CIDNP. The "light" and "dark" NMR spectra were taken in alternating scans in the pulsed Fourier transform mode on a Bruker 360 MHz instrument. Subtraction results in the photo-CIDNP difference spectrum containing lines of the polarized residues. With flavin dyes only tyrosine, histidine, and tryptophan can be polarized. The respective theoretical static accessibility of these residues based upon van der Waal's contact radii have been calculated from the atomic coordinates and provide a basis for evaluating the dynamic NMR photo-CIDNP results and for assigning the resonances. These results suggest that while the four tryptophan residues are completely buried, His-113 and His-14 of the five histidines; and Tyr-165 and Tyr-62 of the fifteen tyrosines are sufficiently exposed to elicit a photo-CIDNP effect. These results confirm and extend the observations previously obtained with theoretical electrostatic programs and FT-NMR measurements.