Institute for Molecular Biophysics, University of Mainz, Germany.
Arch Biochem Biophys. 2010 Mar 15;495(2):112-21. doi: 10.1016/j.abb.2009.12.025. Epub 2010 Jan 4.
Hemocyanins from Crustacea usually are found as 1x6 or 2x6-meric assemblies. An exception is the hemocyanin isolated from thalassinidean shrimps where the main component is a 24-meric structure. Our analysis of oxygen binding data of the thalassinidean shrimp Upogebia pusilla based on a three-state MWC-model revealed that despite the 24-meric structure the functional properties can be described very well based on the hexamer as allosteric unit. In contrast to the hemocyanins from other thalassinidean shrimps the oxygen affinity of hemocyanin from U. pusilla is increased upon addition of l-lactate. A particular feature of this hemocyanin seems to be that l-lactate already enhances oxygen affinity under resting conditions which possibly compensates the rather low intrinsic affinity observed in absence of l-lactate. The fast rate of oxygen dissociation might indicate that in this hemocyanin a higher cooperativity is less important than a fast response of saturation level to changes in oxygen concentration.
甲壳动物的血蓝蛋白通常以 1x6 或 2x6- 聚体的形式存在。一个例外是从长尾虾蛄中分离出的血蓝蛋白，其主要成分是 24- 聚体结构。我们基于三态 MWC 模型对长尾虾蛄 Upogebia pusilla 的氧结合数据进行分析，结果表明，尽管具有 24- 聚体结构，但基于六聚体作为变构单位，可以很好地描述其功能特性。与其他长尾虾蛄的血蓝蛋白不同，U. pusilla 的血蓝蛋白的氧亲和力在添加 l- 乳酸后会增加。这种血蓝蛋白的一个特殊特征似乎是，l- 乳酸在静息条件下就已经增强了氧亲和力，这可能补偿了在没有 l- 乳酸时观察到的相当低的固有亲和力。氧离解的快速速率可能表明，在这种血蓝蛋白中，较高的协同性不如对氧浓度变化的饱和水平的快速响应重要。
