摘要
温度升高使天然紫膜在可见差分吸收光谱中650nm处出现一吸收峰,这意味着紫膜去离子兰膜的形成,而这在脱氧胆酸处理后的紫膜中并未出现.天然紫膜与脱脂紫膜在630nm处的吸收与温度间的关系进一步表明:只有天然紫膜在温度大于68℃才有膜结合离子的释放,释放的离子结合于移去的膜脂之上.紫膜结合离子的释放改变了天然紫膜中bR的构象.热致离子的释放还受介质pH值及介质中离子的影响.pH5.03时,热致离子释放温度提前至温度46℃,而pH7.00,10mM MgCl_2及pH9.00时都没有观察到紫膜离子释放.温度对紫膜在不同pH值时表面电位影响的不一致性进一步表明这是由于膜表面电荷参与的结果.
The Peak at - 650nm appeared in visible-difference absorption spectra of nPM (native purple membrane), but not appeared in that of dPM (delipidated PM) when temperature increased. It meant the formation of deionized blue membrane by heating. The comparison of relationship between absorption of nPM and dPM at 630nm and temperature futher showed that only the nPM can release its binding cations. It suggested that dissociated cations by heating were bound to lipids of PM and the release of cations changed the conformation of BR. Cations released by heating were also affected by pH and ionic strength. At pH 5.03, The temperature which caused cation release of PM decreaced to 46 ℃, but at pH 9.00 or 10mM MgCl2 pH7.00, cation release by heating were prohibited. The effect of temperature on surface potential of nPM was defferent at pH 4.95 and 7.40, It may be the changes of surface charge at different pH.
出处
《生物物理学报》
CAS
CSCD
北大核心
1990年第4期540-544,共5页
Acta Biophysica Sinica
