Table 3. The content of secondary structure in wt HMBS and mutants estimated from far UV CD spectra.

Secondary structure is estimated from far-UV CD spectra using the CDNN algorithm [34].

Mutation	α-helix (%)	β-sheet (%)
Wt	26.7±0.3	23.4±0.3
Wt (X-ray)*	31.2	19.8
R116W	16.2±0.1	41.9±0.4
K132N	27.0±0.7	24.5±1.5
R167W	28.4±0.3	21.8±0.3
R173W	24.9±0.3	26.6±0.5
V215E	17.7±0.2	38.3±0.6

*Determined from the crystal structure of the human enzyme (PBD 3ECR) using the DSSP algorithm [42,43].