Fig. 3

CO-difference spectral analysis. a CO-difference spectrum of cell extract of E. coli DH5α[pUC8:16] expressing VHb; peak and trough at 419 and 436 nm, respectively, characteristic of VHb are indicated. b CO-difference spectrum of cell extract of untransformed N. europaea; characteristic peak at 414 nm is indicated. c CO-difference spectra of cell extracts from three individual isolates of N. europaea transformed with vgb on plasmid pSK2; peak at 416 nm and shoulder at 423 nm are indicated.