In their Communication on p. 1562 ff., K. Gruber et al. describe a structure correlation of active-site loop conformations for Old Yellow Enzymes (OYEs) in combination with their known stereopreferences in the reduction of an aromatic nitroalkene. This revealed three different clusters of OYEs. An analysis of these structural clusters enabled the identification of sequence motifs, which are highly conserved throughout the whole enzyme family. These motifs may be used to predict structural and biocatalytic properties of OYEs. The cover picture shows a schematic representation in which sequences of OYEs are scanned for classification according to the identified sequence motifs. Above the sequences, structures of OYEs illustrating distinct clusters are shown.