AbstractThe far uv circular dichroism (CD) and infrared spectra of bacterial spinae are reported. Estimates of the protein secondary structure were obtained by three‐component curve‐fitting methods supplemented by rank and factor analysis of CD data matrices. Native spinae were shown to contain approximately 88% antiparallel β‐sheet, 7% α‐helix, and 5% unordered structure based on estimates using poly(L‐lysine). Basis CD spectra derived from globular proteins were shown to give unreliable estimates.