An infrared spectroscopic study of β‐galactosidase structure in aqueous solutions

Fourier‐transform infrared spectroscopy has been used to elucidate the secondary structure of E. coli β‐galactosidase in aqueous solution. The structure of this enzyme was previously unknown above the level of the amino acid sequence. Spectra have been recorded in both H2O and D2O media; mutually complementing data are obtained, that provide unambiguous structural information. The results show that β‐galactosidase contains 40% β‐sheet and 35% α‐helical structure, with smaller proportions of random coil (12%) and β‐turns (13%).