THE DETERMINATION OF BINDING CONSTANTS OF MICELLAR-PACKAGED GRAMICIDIN-A BY C-13-NMR AND NA-23-NMR

被引:30
作者
JING, NJ [1 ]
PRASAD, KU [1 ]
URRY, DW [1 ]
机构
[1] UNIV ALABAMA, MOLEC BIOPHYS LAB, BIRMINGHAM, AL 35294 USA
来源
BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES | 1995年 / 1238卷 / 01期
关键词
GRAMICIDIN A; C-13; LABELED; DODECYL PHOSPHOCHOLINE MICELLE; IONIC TITRATION; CIRCULAR DICHROISM;
D O I
10.1016/0005-2736(95)00095-K
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Based on the malonyl gramicidin A structure of a single-stranded head-to-head hydrogen bonded right-handed, beta(6.3)-helix in dodecyl phosphocholine (DPC) lipid micelles (Jing et al. (1994) Biophys. J. 66, A353), the determination of cation binding sites for gramicidin A (GA) in DPC micelles becomes a significant step in the study of ion transport through the model channel. First, the investigation of cation binding sites in DPC micellar packaged gramicidin A was achieved by C-13-NMR experiments at 30 degrees C using four C-13 labeled GA samples. Then, the analyses based on two different equations, one for single and one for double occupancy, were employed to evaluate the correct occupancy model for GA in DPC micelles. The results clearly indicate double occupancy to be correct for Na+ ion as well as for K+, Rb+, Cs+ and Tl+ ions. Finally, the binding constants for Na+ ion were also estimated by the measurement of the longitudinal relaxation time (T-1) using Na-23-NMR of the same sample at the same temperature as used for the C-13-NMR study. The binding constants obtained from Na-23-NMR are essentially equivalent to those determined from the C-13-chemical shifts.
引用
收藏
页码:1 / 11
页数:11
相关论文
共 34 条