水溶液中N-6,N-6-二甲基腺嘌呤受限内旋转的H核磁共振研究。

H nuclear magnetic resonance study of restricted internal rotation of N-6,N-6-dimethyladenine in aqueous solution.

作者信息

Pitner T P, Glickson J D

出版信息

Biochemistry. 1975 Jul 15;14(14):3083-7. doi: 10.1021/bi00685a007.

Abstract

Kinetics of internal rotation about the C(6)-N(6) bond of N-6,N-6-dimethyladenine (M2-6A) was investigated by -1H nuclear magnetic resonance line-shape analysis of the methyl resonances (220 MHz). Rates of rotation were determined for M2-6A deuterated at N(1) and for neutral M2-6A. Activation parameters for monodeuterated M2-6A at 22 degrees are Ea = 13.8kcal/mol, log A = 12.6, incrementG++=14.9 kcal/mol, incrementH++ = 13.1 kcal/mol, incrementS++ = minus 5.8 eu; for neutral M2-6A: Ea = 15.5 kcal/mol, log A = 14.9, incrementG++ = 12.6 kcal/mol, incrementH++ = 14.9 kcal/mol, incrementS++ =7.8 eu. Vertical stacking of bases interferes with internal rotation of the dimethylamino group.

摘要

通过对甲基共振（220兆赫兹）进行¹H核磁共振线形分析，研究了N⁶,N⁶ - 二甲基腺嘌呤（M2 - 6A）围绕C(6)-N(6)键的内旋转动力学。测定了在N(1)处氘代的M2 - 6A以及中性M2 - 6A的旋转速率。22℃下单氘代M2 - 6A的活化参数为：Ea = 13.8千卡/摩尔，log A = 12.6，ΔG‡ = 14.9千卡/摩尔，ΔH‡ = 13.1千卡/摩尔，ΔS‡ = -5.8熵单位；中性M2 - 6A的活化参数为：Ea = 15.5千卡/摩尔，log A = 14.9，ΔG‡ = 12.6千卡/摩尔，ΔH‡ = 14.9千卡/摩尔，ΔS‡ = 7.8熵单位。碱基的垂直堆积会干扰二甲基氨基的内旋转。