The effect of ring currents on carbon chemical shiftsin cytochromes

详细信息    查看全文

• 作者：Laurence Blanchard ; C. Neil Hunter and Michael P. Williamson
• 关键词：Carbon chemical shifts ; Cytochrome c ; Secondary structure ; Heme ring current effect
• 刊名：Journal of Biomolecular NMR
• 出版年：1997
• 出版时间：1997
• 年：1997
• 卷：9
• 期：4
• 页码：389-395
• 全文大小：326 KB

文摘

Calculations suggest that some carbon chemical shifts in proteinsshould have large ring current shifts (>1 ppm). We present13C, 15N and 1H assignments forcytochrome c₂ from Rhodospirillum rubrum, compare these withshifts for other cytochromes c, and show that the calculated ring currentshifts are similar to experimentally observed shifts, but that there remainsubstantial conformation-dependent shifts of side-chain carbons. Ringcurrent shifts as large as 6 ppm are observed. We show that the ring currenteffects do not seriously affect the Chemical Shift Index method fordelineating secondary structure, but may have an impact on more precisemethods for generating structural constraints.