Most dehydrogenases that use NAD or NADP bind the cofactor in a conserved protein domain called the Rossmann fold (named for Michael Rossmann, who deduced the structure of lactate dehydrogenase and first described this structural motif).
● A domain is a section of protein structure sufficient to perform a particular chemical or physical task such as binding of a substrate.
●The Rossmann fold typically consists of a six stranded parallel beta sheet and four associated alpha helices
●Characterised by alternating beta-alpha-beta(beta strand-alpha helix-beta strand)
● The beta strands are hydrogen bonded forming a beta sheet
● The beta alpha beta fold structure is commonly observed in dinucleotide coenzymes such as FAD, SAM,NAD,NADP
● The association between a dehydrogenase and NAD/NADP is relatively loose
● So the coenzyme can quickly diffuse from one enzyme to other, acting as water soluble carrier of electrons from one metabolite to another
●The enzymes which have Rossman fold are Rossmann enzymes
●Oxidoreductase with Rossman fold are:-
☆ Lactate dehydrogenase
☆ Alcohol dehydrogenase
☆ Glyceraldehyde-3 -phosphate dehydrogenase
☆ Malate dehydrogenase
☆ 6 phosphogluconate dehydrogenase
☆ D-glycerate dehydrogenase