Kreim Michael, Giersch Christoph
Institut für Botanik, Darmstadt University of Technology, Schnittspahnstr. 3-5, 64287 Darmstadt, Germany.
Phytochemistry. 2007 Aug-Sep;68(16-18):2152-62. doi: 10.1016/j.phytochem.2007.03.043. Epub 2007 May 30.
To measure the kinetics of enzymes, the proteins are usually assayed in vitro after isolation from their parent organisms. We make an attempt to show how one might determine enzyme elasticities in an intact system by a multiple modulation approach. Certain target enzymes are modulated in their activities and the changes in metabolite concentrations and flux rates upon the modulations are used to calculate the enzyme elasticities. Central to this approach is that the modulations must be independent of each other, and an algorithm is developed for finding all independent modulations that allow determining the elasticities of a given enzyme. This approach is applied to a mass-action model of the Calvin cycle. The goal is to determine the elasticities of as many enzymes as possible by modulating the activities of as few of them as possible. It is shown that the elasticities of 20 (out of 22) Calvin cycle enzymes can be determined by modulating just five reactions. Moreover, visualization of independence of modulations may be used to decompose the Calvin cycle into several sections that are independent of each other regarding flow of matter and information.
为了测量酶的动力学，通常在从其亲本生物体中分离出来后，在体外对蛋白质进行测定。我们试图展示如何通过多重调节方法在完整系统中确定酶的弹性。某些目标酶的活性受到调节，并利用调节后代谢物浓度和通量率的变化来计算酶的弹性。该方法的核心是调节必须相互独立，并且开发了一种算法来找到所有允许确定给定酶弹性的独立调节。此方法应用于卡尔文循环的质量作用模型。目标是通过调节尽可能少的酶的活性来确定尽可能多的酶的弹性。结果表明，只需调节五个反应就可以确定（22个中的）20个卡尔文循环酶的弹性。此外，调节独立性的可视化可用于将卡尔文循环分解为几个在物质和信息流方面相互独立的部分。
