Muszkat K A, Preygerzon V, Tu A T
Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel.
J Protein Chem. 1994 Apr;13(3):333-7. doi: 10.1007/BF01901566.
CIDNP and COSY measurements were applied to study aromatic side chain interactions and conformations in myotoxin alpha, a Crotalus venom toxin which acts as blocker of the Ca2+ influx in the sarcoplasmic reticulum calcium pump. New evidence for the existence of a hydrophobic aromatic cluster at the amino terminus was obtained. This cluster consists of Tyr1, His5, His10, and (possibly) F12. The CIDNP data clearly establish that the usual order of the tyrosine 2, 6 and 3, 5 proton signals of Tyr1 is inverted, because of the large diamagnetic shielding effects of one ring on the other. The lines of the 2, 6 ring protons of Tyr1 and proton 4 in each of His5 and His10 are significantly broadened, an outcome of the side-chain hydrophobic interaction. The aromatic cluster could possibly present a hydrophobic sticky patch for binding of toxin by Ca2+ ATPase.
采用化学诱导动态核极化（CIDNP）和同核自旋-自旋相关谱（COSY）测量技术研究了肌毒素α中芳香族侧链的相互作用和构象。肌毒素α是一种响尾蛇毒液毒素，可作为肌浆网钙泵中钙离子内流的阻滞剂。获得了氨基末端存在疏水芳香簇的新证据。该簇由Tyr1、His5、His10和（可能的）F12组成。CIDNP数据清楚地表明，由于一个环对另一个环的大抗磁屏蔽效应，Tyr1的酪氨酸2、6和3、5质子信号的通常顺序发生了反转。Tyr1的2、6环质子以及His5和His10中每个的质子4的谱线明显变宽，这是侧链疏水相互作用的结果。芳香簇可能为Ca2+ATP酶结合毒素提供一个疏水粘性区域。
