Menard M P, Cousins R J
J Nutr. 1983 Jul;113(7):1434-42. doi: 10.1093/jn/113.7.1434.
Zinc uptake into isolated brush border membrane vesicles from rat intestine was investigated by using a rapid filtration technique. Uptake was saturable at 0.2 mM extravesicular zinc, while at 1.0 mM zinc uptake was nonsaturable. ATP and Na+ did not stimulate uptake. Some binding of zinc was noted at zero intravesicular space indicating some membrane binding may occur during transport. Initial rates of uptake were linear up to 0.3 and 0.45 mM extravesicular zinc with vesicles prepared from rats fed adequate and deficient amounts of zinc, respectively. Kinetic analysis of uptake data yielded a Km of 0.38 mM and Jmax of 5.4 nmol X minute-1 X mg protein-1 with vesicles from zinc-adequate rats. With vesicles from zinc-depleted rats the Km was 0.44 mM and Jmax was 12.0 nmol X minute-1 X mg protein-1. These uptake data suggest the brush border membrane transport system for zinc is influenced by zinc status.
采用快速过滤技术研究了锌进入大鼠肠道分离的刷状缘膜囊泡的过程。在囊泡外锌浓度为0.2 mM时，摄取呈饱和状态，而在锌浓度为1.0 mM时，摄取不饱和。ATP和Na+不刺激摄取。在囊泡内空间为零时观察到一些锌的结合，表明在转运过程中可能发生一些膜结合。分别用喂食足量和缺锌大鼠制备的囊泡，在囊泡外锌浓度高达0.3和0.45 mM时，摄取的初始速率呈线性。对摄取数据的动力学分析得出，来自锌充足大鼠的囊泡的Km为0.38 mM，Jmax为5.4 nmol·分钟-1·mg蛋白-1。来自缺锌大鼠的囊泡的Km为0.44 mM，Jmax为12.0 nmol·分钟-1·mg蛋白-1。这些摄取数据表明，锌的刷状缘膜转运系统受锌状态的影响。
