淡水虾肠道中钠和氯协同转运过程中的变构协同性。

Allosteric cooperativity during intestinal cotransport of sodium and chloride in freshwater prawns.

作者信息

Ahearn G A, Tornquist A

出版信息

Biochim Biophys Acta. 1977 Dec 1;471(2):273-9. doi: 10.1016/0005-2736(77)90255-3.

PMID:921981

Abstract

Coupled influxes of sodium and chloride across the mucosal border of a freshwater prawn intestine were sigmoidal functions of luminal ion concentrations, indicative of a cooperative allosteric transport process. This process had a higher affinity for Cl (KCl = 94 mM) than for Na (KNa = 155 mM), maximally transported twice as much cation as anion (JNa max = 1.6; JCl max = 0.75 mumol-cm-2-h-1), and exhibited identical Hill interaction indices for both ions nNa = 3.4; nCl = 3.5). The suggestion is made that this cooperative carrier mechanism may be regulatory, maintaining relatively constant luminal ion concentrations which, in turn may facilitate ion-dependent absorption of non-electrolytes.

摘要

淡水虾肠道黏膜边界处钠和氯的协同内流是管腔离子浓度的S形函数，这表明存在协同变构转运过程。该过程对Cl的亲和力（KCl = 94 mM）高于对Na的亲和力（KNa = 155 mM），最大转运时阳离子的转运量是阴离子的两倍（JNa max = 1.6；JCl max = 0.75 μmol·cm⁻²·h⁻¹），并且两种离子的希尔相互作用指数相同（nNa = 3.4；nCl = 3.5）。有人提出，这种协同载体机制可能具有调节作用，维持相对恒定的管腔离子浓度，进而可能促进非电解质的离子依赖性吸收。