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Alda‐1 modulates the kinetic properties of mitochondrial aldehyde dehydrogenase ( ALDH 2)
Author(s) -
BelmontDíaz Javier A.,
YovalSánchez Belem,
CallejaCastañeda Luis F.,
Pardo Vázquez Juan P.,
RodríguezZavala José S.
Publication year - 2016
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.13833
Subject(s) - aldh2 , aldehyde dehydrogenase , cysteine , chemistry , aldehyde , biochemistry , enzyme , activator (genetics) , nad+ kinase , biophysics , stereochemistry , catalysis , biology , gene
Mitochondrial aldehyde dehydrogenase ( ALDH 2) has been proposed as a key enzyme in cardioprotection during ischemia–reperfusion processes. This proposal led to the search for activators of ALDH 2 with the aim to develop cardioprotective drugs. Alda‐1 was the first activator of ALDH 2 identified and its cardioprotective effect has been extensively proven in vivo ; however, the mechanism of activation is not fully understood. A crystallographic study showed that Alda‐1 binds to the entrance of the aldehyde‐binding site; therefore, Alda‐1 should in essence be an inhibitor. In the present study, kinetic experiments were performed to characterize the effect of Alda‐1 on the properties of ALDH 2 (kinetic parameters, determination of the rate‐limiting step, reactivity of the catalytic cysteine) and on the kinetic mechanism (type of kinetics, sequence of substrates entering, and products release). The results showed that Alda‐1 dramatically modifies the properties of ALDH 2, the K m for NAD + decreased by 2.4‐fold, and the catalytic efficiency increased 4.4‐fold; however, the K m for the aldehyde increased 8.6‐fold, thus, diminishing the catalytic efficiency. The alterations in these parameters resulted in a complex behavior, where Alda‐1 acts as inhibitor at low concentrations of aldehyde and as an activator at high concentrations. Additionally, the binding of Alda‐1 to ALDH 2 made the deacylation less limiting and diminished the p K a of the catalytic cysteine. Finally, NADH inhibition patterns indicated that Alda‐1 induced a change in the sequence of substrates entry and products release, in agreement with the proposal of both substrates entering ALDH 2 by the NAD + entrance site.