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A more detailed examination of the influence of magnesium ion on ALDH2 enzyme activity ([dagger]).

Within many mammalian systems aldehyde dehydrogenases (ALDH's) convert toxic aldehydes into more manageable carboxylic acids. Nicotinamide adenine dinucleotide ([NAD.sup.+]) is an essential coenzyme for this enzymatic process to occur. Through the course of a five step reaction scheme (1) [NAD.sup.+] is converted to its reduced form (NADH) and released. The release of NADH from the ALDH is necessary for further turnover of the enzyme. The addition of magnesium ions to these ALDH systems modulates activity, in some cases increasing activity (ALDH2) and in others, like ALDH1, decreasing activity. The specific role of the magnesium ions the reaction scheme of the different ALDH's is in the process of being resolved. (2)

Our research is focused on using the intrinsic fluorescence of NADH to provide fundamental information regarding factors that influence the enzyme-cofactor interactions. By applying time resolved fluorescence spectroscopy we have been able to distinguish between free NADH in solution ([] = 0.4 ns) and NADH bound to recombinant rat ALDH2 ([tau] = 6.0 ns) in the presence of magnesium ions. With such as dramatic difference in fluorescence lifetimes, we have been able to determine ALDH2 enzyme activity, the steady state NADH-ALDH2 complex concentration, the rate of rate of NADH displacement from NADH-ALDH2 complex and the dissociation constant for NADH with ALDH2 under a wide range of magnesium ion concentrations. From these results we have been able to more clearly identify the influence the magnesium ion has on individual steps in the overall five step reaction. Future studies will involve closely examining the influence other divalent metal cations have on this system.


Jordan Karlstad * ([double dagger]), Thomas P. Gonnella ([double dagger]), and Matthew J. Picklo ([section])

Division of Science and Mathematics, Mayville State University, Mayville, ND 58257

([dagger]) This project is supported by NIH grant P20 RR016741 from the INBRE Program of the National Center for Research Resources.

([double dagger]) Division of Science and Mathematics, Mayville State University

([section]) Department of Pharmacology, Physiology, and Therapeutics, University of North Dakota

(1) Hammen, P. K.; Allali-Hassani, A.; Hallenga, K.; Hurley, T.D.; Weiner, H. Biochemistry 2002, 41, 7156.

(2) Ho, K. K.; Hurley, T.D.; Weiner, H. Biochemistry 2006, 45, 9445.
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Author:Karlstad, Jordan; Gonnella, Thomas P.; Picklo, Matthew J.
Publication:Proceedings of the North Dakota Academy of Science
Article Type:Technical report
Geographic Code:1U4ND
Date:Apr 1, 2008
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