Selection of strains, which were generated in this study and used for production of recombinant SH variants.

aSH variants: wt = wildtype SH, untagged; 1 = SH variant 1: four-subunit enzyme HoxFUYH with N-terminally StrepII-tagged HoxF; 2 = SH variant 2: six-subunit enzyme HoxFUYHI2 with N-terminally StrepII-tagged HoxI.
bAll recombinant strains were generated with E. coli BL21Star™ (DE3) as the basic strain.
cSpecific activities were determined in extracts from cells obtained in three independent ‘autoinduction’ batches under optimized growth conditions outlined in the methods section of the paper. Given values are arithmetic means of the triplicate measurements. Statistical values indicated (±) represent standard deviations. 1 Unit is defined as the H2-mediated reduction of 1 µmol NAD+per minute.