β‐Conformation in γ‐globulin

An oriented film of γ‐globulin fibrils obtained by precipitating human γ‐globulin with anti‐human γ‐globulin horse serum was examined with polarized infrared light. When the film was examined with light polarized parallel to the fibril axis, the amide I band was observed at 1635 cm. −1 , indicating the cross‐β structure in γ‐globulin fibrils. The reasonableness of this structure for γ‐globulin is discussed by comparing its optical rotatory dispersion constants with those of poly‐ O ‐acetyl‐ L ‐serine, which had previously been shown to be the intrachain cross‐β structure.