Measuring Kinetic Isotope Effects on Enzyme Systems Through TRESI-MS

摘要

The ability to measure kinetic isotope effects by time-resolved electrospray ionization mass spectrometry can now be realized. For the first time, a 1 deg ~(13)C kinetic isotope effect of 1.0322 +- 0.0100 on the chymotrypsin catalyzed hydrolysis of p-NPA is established using online TRESI-MS, which is significantly near the KIE of 1.030 +- 0.002 reported by Hess et.al. using offline isotope ratio mass spectrometry. The robustness of TRESI towards measuring a large isotope effect, such as that seen with the yeast alcohol dehydrogenase oxidation of ethanol by way of hydrogen transfer to the NAD~(+) cofactor, represents the future work for this project and will solidify this novel technique as method to measure kinetic isotope effects on enzyme systems.