[Structure and regulation of the assembly of bacteriophage T4 fibrillar proteins. I. Isolation and spectral properties of long fibers].

A preparative procedure for purification of the biological active proximal (A) and distal (BC') parts of bacteriophage T4 long-tail fibers is described. Absorption spectra of these proteins in the near ultraviolet region were measured. The absorption coefficients were determined on the basis of the nitrogen content, the absorption coefficient for the A part is epsilon 0.1% 277 nm = 0.93 +/- 0.06 and for the BC' part is epsilon 0.1%, 277,5 nm = 1.01 +/- 0.08. Calculations of the secondary structure from CD spectra show that there is a high content of beta-structure: 41% in the A part and 51% in the BC' part,--and also that alpha-helix are present in the native complex: 20% in A and 7% in BC'. A model for the spatial organisation of long fibers is proposed.