I am working with an aldehyde dehydrogenase that is NAD-specific and was wondering why it doesn't utilise NADP despite the difference between the 2 cofactors is only a phosphate group. Any thoughts on this or good reference to read will be appreciated.
An explanation for the distinct roles of NADP and NAD:
"The total concentration of NAD+ + NADH in most tissues is about 10-5 M; that of NADP+ + NADP[H] is about 10 times lower. In many cells and tissues, the ratio of NAD+ (oxidized) to NADH (reduced) is high, favoring hydride transfer to NAD+ to form NADH; by contrast, NADPH (reduced) is generally present in greater amounts than its oxidized form, NADP+, favoring hydride transfer from NADPH. This reflects the specialized metabolic roles of the two cofactors: NAD+ generally functions in catabolic oxidations, and NADPH is the usual cofactor in anabolic reductions. A few enzymes will use either cofactor, but most show a strong preference for one cofactor over the other. This functional specialization allows a cell to maintain two distinct pools of electron carriers in the same cellular compartment."
from http://www.bioinfo.org.cn/book/biochemistry/chapt13/bio7.htm
Hi Adam,
Thanks for this great insight, it makes a lot of sense. However, is there any evidence at the molecular or mechanistic level which suggests how these enzymes are able to selectively use only one of the cofactors? For example differences in there pyridine nucleotide binding sites..
Someone wrote a paper on this very subject:
Article NADP-Dependent enzymes. I: Conserved stereochemistry of cofa...
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