Widdas W F, Baker G F, Baker P
Department of Biology, Royal Holloway College, University of London, Egham, Surrey, Great Britain.
Cytobios. 1994;80(320):7-24.
The red cell shrinkage rate due to bicarbonate in media of high pH (ca 9.4) has been compared with the hydroxyl shrinkage rate on a per mM basis. The shrinkage rate due to bicarbonate was only half that due to OH-/Cl- exchanges. It was therefore deduced that the Jacobs-Stewart cycle was limited by the carbonic anhydrase step and not by the rate of transport on the anion exchanger protein. To explain this and other anomalies the hypothesis is made that carbonic anhydrase has evolved as a pH-dependent catalyst with specific physiological functions in pH regulation and in other cellular mechanisms. The kinetic theory and some physiological implications of the hypothesis are discussed.
在高pH值（约9.4）的介质中，已将因碳酸氢盐导致的红细胞收缩率与每毫摩尔的羟基收缩率进行了比较。因碳酸氢盐导致的收缩率仅为因OH⁻/Cl⁻交换导致的收缩率的一半。因此推断，雅各布斯 - 斯图尔特循环受碳酸酐酶步骤的限制，而非受阴离子交换蛋白上的转运速率限制。为了解释这一现象及其他异常情况，提出了如下假说：碳酸酐酶已演化为一种pH依赖性催化剂，在pH调节及其他细胞机制中具有特定的生理功能。讨论了该假说的动力学理论及一些生理意义。
