Goto R, Hanamura S, Tamemasa O
J Pharmacobiodyn. 1982 Oct;5(10):780-8. doi: 10.1248/bpb1978.5.780.
In order to ascertain the significance of the hydrophobic region in the carrier protein responsible for the D-leucine transport reported previously, the effects of p-chloromercuribenzene sulfonate (PCMBS) were investigated on the transport of D- and L-leucines in Ehrlich ascites tumor cells. The uptake of D-leucine in the presence of PCMBS was inhibited more strongly than that of L-leucine. Km values for D-leucine uptake increased with increasing concentration of PCMBS, while those for L-leucine showed only a little increase. D-Leucine uptake was restored considerably from the PCMBS inhibition by washing with buffer, whereas L-leucine uptake was only slightly affected. The inhibition of D-leucine exit by PCMBS was also higher than that of L-leucine. These results suggest that the binding site of PCMBS for the carrier protein of Ehrlich cells is involved in its hydrophobic region that would be more significant for the binding of alkyl side chain D-leucine than that of L-leucine.
为了确定先前报道的负责D-亮氨酸转运的载体蛋白中疏水区域的重要性，研究了对氯汞苯磺酸盐（PCMBS）对艾氏腹水瘤细胞中D-和L-亮氨酸转运的影响。在PCMBS存在下，D-亮氨酸的摄取比L-亮氨酸受到更强的抑制。D-亮氨酸摄取的Km值随PCMBS浓度的增加而增加，而L-亮氨酸的Km值仅略有增加。通过用缓冲液洗涤，D-亮氨酸摄取从PCMBS抑制中得到相当程度的恢复，而L-亮氨酸摄取仅受到轻微影响。PCMBS对D-亮氨酸外流的抑制也高于L-亮氨酸。这些结果表明，PCMBS与艾氏细胞载体蛋白的结合位点涉及其疏水区域，该区域对烷基侧链D-亮氨酸的结合比对L-亮氨酸的结合更重要。
