CIM device for enzyme kinetics experiment aboard the International Space Station

Abstract

The main objective of this experiment is to verify the differences in kinetic parameters of enzymes reaction aboard the ISS. For this experiment the invertase enzyme was selected, as a case study in microgravity. It is expected that significant differences occur in the sucrose hydrolysis by invertase, due to diffusion phenomenon in microgravity. The experiment consists of two series of tests, each one with five different sucrose concentrations, to evaluate the invertase kinetics. The reaction is allowed during a period of time, after which the reactions are interrupted by addition of an enzyme inhibitor. The samples of the enzymes, after reaction, must return to earth for biochemical analysis in laboratory. It is expected that significant differences should occur in the hydrolysis of sucrose by invertase, due the diffusion phenomenon, that suffers alterations in microgravity. To perform this experiment in microgravity on ISS, CIM device was developed, with two sets of 5 chambers each, in a total of 10, to realize the mixture of two liquids and the enzyme. This compact device requires no electric power, and it can easily be operated by an astronaut manually. This device is an important evolution over the previous version, MEK device, which flew on ISS Brazilian "Centenary Mission", in March, 2006. The results were partly satisfactory and indicated an increase in reaction rate values, but a metal contamination of the samples due to the resistor oxidation, interfered in the biochemical reaction: this required confirmation and of the experiment and confrontation of data. This experiment aims at the study of the enzymatic kinetics of invertase, which catalyzes carbohydrates hydrolysis, such as sucrose, producing glucose and fructose. The study of enzymatic kinetics is fundamental for the comprehension of the enzymes action mechanism, in and out of the cells, and this may lead to the design of more efficient enzymatic bioreactors. Therefore, the study of the effects of microgravity on the enzymes action can be helpful to better understand their action mechanism on earth, and then to think of enzymatic processes and microorganisms applications, both on earth and in space. Copyright ©2010 by the International Astonautical Federation. All rights reserved.