Rossmann fold

It was subsequently found that most dehydrogenases that utilize NAD or NADP contain this same structurally conserved Rossmann fold motif.

[10] 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.

[11] Since this segment is in contact with the ADP portion of dinucleotides such as FAD, NAD and NADP it is also called as an "ADP-binding beta-beta fold.

[12] The N- and C-terminal domains of UgdG share structural features with ancient mitochondrial ribonucleases named MAR.

This observation reinforces that the Rossmann structural motifs found in NAD(+)-dependent dehydrogenases can have a dual function working as a nucleotide cofactor binding domain and as a ribonuclease.

[4] Phylogenetic analysis of the NADP binding enzyme adrenodoxin reductase revealed that from prokaryotes, through metazoa and up to primates the sequence motif difference from that of most FAD and NAD-binding sites is strictly conserved.

[13] In many articles and textbooks, a Rossmann fold is defined as a strict repeated series of βαβ structure.

Yet, comprehensive examination of the Rossmann folds in many NAD(P) and FAD binding sites revealed that only the first βα structure is strictly conserved.

[13] The result by Hanukoglu (2017) is corroborated by Medvedev et al. (2020), in the form of an ECOD "H-group" called "Rossmann-related".