Editing Rossmann fold (section)

== Structure ==
[[File:Rossmann_fold_schematic.svg|thumb|360px|Schematic diagram of a six stranded Rossmann fold]]
{{multiple image
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| image1      = 5KKA_A_Rossmann_fold_front.png
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| alt1        = Front view
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| footer      = Cartoon diagram of the Rossmann fold (helices A-F red and strands 1-6 yellow) from ''[[E. coli]]'' [[malate dehydrogenase]] ({{PDBe-KB|5KKA}}).
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The Rossmann fold is composed of six parallel [[beta strand]]s that form an extended [[beta sheet]]. The first three strands are connected by [[Alpha helix|α- helices]] resulting in a beta-alpha-beta-alpha-beta structure.  This pattern is duplicated once to produce an inverted tandem repeat containing six strands. Overall, the strands are arranged in the order of 321456 (1 = N-terminal, 6 = C-terminal).<ref>{{cite web | title = NAD(P)-binding Rossmann-fold domains | work = [[Structural Classification of Proteins database|SCOP: Structural Classification of Proteins]] | url = http://scop.mrc-lmb.cam.ac.uk/scop/data/scop.b.d.c.A.html | access-date = 2017-12-17 | archive-date = 2018-11-21 | archive-url = https://web.archive.org/web/20181121202910/http://scop.mrc-lmb.cam.ac.uk/scop/data/scop.b.d.c.A.html | url-status = dead }}</ref>  Five stranded Rossmann-like folds are arranged in the order 32145.<ref>{{cite web | title = Nucleotide-binding domain | work = [[Structural Classification of Proteins database|SCOP: Structural Classification of Proteins]] | url = http://scop.mrc-lmb.cam.ac.uk/scop/data/scop.b.d.e.A.html | access-date = 2017-12-17 | archive-date = 2018-12-07 | archive-url = https://web.archive.org/web/20181207052012/http://scop.mrc-lmb.cam.ac.uk/scop/data/scop.b.d.e.A.html | url-status = dead }}</ref> The overall tertiary structure of the fold resembles a three-layered sandwich wherein the filling is composed of an extended beta sheet and the two slices of bread are formed by the connecting parallel alpha-helices.<ref name="Hanukoglu_2015" />

One of the features of the Rossmann fold is its [[cofactor (biochemistry)|co-factor]] binding specificity. Through the analysis of four NADH-binding enzymes, it was found that in all four enzymes the nucleotide co-factor entailed the same conformation and orientation with respect to the polypeptide chain.<ref name="Hanukoglu_2015"/>

The fold may contain additional strands joined by short helices or coils.<ref name="Hanukoglu_2015" /> The most conserved segment of Rossmann folds is the first beta-alpha-beta segment. Phosphate-binding loop is located between the first beta-strand and alpha-helix. On the tip of the second beta-strand, there is a conserved aspartate residue that is involved in ribose binding.<ref>{{cite journal | vauthors = Longo LM, Jabłońska J, Vyas P, Kanade M, Kolodny R, Ben-Tal N, Tawfik DS | title = On the emergence of P-Loop NTPase and Rossmann enzymes from a Beta-Alpha-Beta ancestral fragment | journal = eLife | volume = 9 | pages = e64415 | date = December 2020 | pmid = 33295875 | pmc = 7758060 | doi = 10.7554/eLife.64415 | veditors = Deane CM, Boudker O | doi-access = free }}</ref> Since this segment is in contact with the [[Adenosine diphosphate|ADP]] portion of dinucleotides such as [[Flavin adenine dinucleotide|FAD]], [[Nicotinamide adenine dinucleotide|NAD]] and [[Nicotinamide adenine dinucleotide phosphate|NADP]] it is also called as an "ADP-binding beta-beta fold.