Nuclear magnetic resonance studies of amino acids and proteins. Side-chain mobility of methionine in the crystalline amino acid and in crystalline sperm whale (Physeter catodon) myoglobin.
Nuclear magnetic resonance studies of amino acids and proteins. Side-chain mobility of methionine in the crystalline amino acid and in crystalline sperm whale (Physeter catodon) myoglobin.
复制标题
氨基酸和蛋白质的核磁共振研究。
DOI：
10.1021/bi00277a028
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发表时间：
1983
期刊：
影响因子：
2.9
通讯作者：
Oldfield,E
中科院分区：
文献类型：
--
作者：
Keniry,MA;Rothgeb,TM;Smith,RL;Gutowsky,HS;Oldfield,E
本文测定了~-[t-~ H~]蛋氨酸、D，L晶格中的~-[t-~ H ~]蛋氨酸和结晶固态的[S-甲基-2H ~3]蛋氨酸的氘（~ 2 H）核磁共振（NMR）谱和自旋-晶格弛豫时间（TI）随温度的变化。除了通过使用磁排序方法获得[~-~ H~]甲硫氨酸标记的抹香鲸（Physeter curodon）肌红蛋白的2 H T1和线宽结果作为温度的函数之外[Rothgeb，TM，& Oldfield，E.（1981）J. Biof. Chem.256，1432-14461。结果表明，在L-氨基酸中，在低温（5-10 ℃）下，具有8.3 f1 kJ的活化能（AE*）的甲基旋转主导TI，而在较高温度下，发生另外的大幅度侧链运动，这引起ZH NMR线形和TI的变化。这种运动在D，L晶格中被抑制，表明晶格效应可能对固态无水氨基酸的流动性有很强的影响。在S6处进一步取代形成锍盐[S-Me-hyl-H-]-甲硫氨酸导致AE* 大幅增加至15.9kJ，该值与在缬氨酸和亮氨酸中发现的14-16 kJ相当，所述缬氨酸和亮氨酸含有结构相似的异丙基部分。这些结果表明，对甲基旋转xere的非常低的屏障目前在研究溶液中、膜中和结晶固态中蛋白质的动态结构中引起了相当大的兴趣（威廉姆斯，1978; Frauenfelder等人，1979年; Frauenfelder和Petsko，1980年; Artymiuk等人，1979; Gurd和Rothgeb，1979; Karplus和McCammon，1981; Keniry等人，1982; Schramm等人，1981; Schramm & Oldfield，1982）。核磁共振（NMR）波谱，由于其对超过1000个时间尺度的宽范围的灵敏度，
We have obtained deuterium (2H) nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation times (TI) of~-[t-~ H~] methionine,~-[t-~ H~] methionine in a D, L lattice, and [S-methyf-2H3] methionine in the crystalline solid state, as a function of temperature, in addition to obtaining 2H T1 and line-width results as a function of temperature on [~-~ H~] methionine-labeled sperm whale (Physeter curodon) myoglobins by using the method of magnetic ordering [Rothgeb, TM, & Oldfield, E.(1981) J. Biof. Chem. 256, 1432-14461. The results indicate that in the L-amino acid, methyl rotation having an activation energy (AE*) of 8.3 f 1 kJ dominates TI at low temperatures (5-10 “C), while at higher temperatures an additional large-amplitude side-chain motion occurs which causes changes in the ZH NMR line shape and Tl. This motion is inhibited in the D, L lattice, indicating that lattice effects may have a strong effect on the mobility of anhydrous amino acids in the solid state. Further substitution at S6 to form the sulfonium salt [S-me~ hyl-~ H~]-methionine causes a large increase in AE*, to 15.9 f 2 kJ, a value comparable to the 14-16 kJ found in valine and leucine, which contain the structurally similar isopropyl moiety. These results suggest that the very low barriers to methyl rotation xere is currently considerable interest in investigating the dynamic structures of proteins in solution, in membranes, and in the crystalline solid state (Williams, 1978; Frauenfelder et al., 1979; Frauenfelder & Petsko, 1980; Artymiuk et al., 1979; Gurd & Rothgeb, 1979; Karplus & McCammon, 1981; Keniry et al., 1982; Schramm et al., 1981; Schramm & Oldfield, 1982). Nuclear magnetic resonance (NMR)’spectroscopy, because of its sensitivity to the wide range of time scales over