SOME CONFORMATIONAL STUDIES OF LARVAL CUTICULAR PROTEIN FROM CALLIPHORA-VICINA

Protein extracted from lipid-free late instar larval cuticles of Calliphora vicina consists of a mixture of similar proteins which, when in solution (phosphate buffer pH 6 or 0.05 M NaCl), exist largely in a disordered conformation as shown by infrared (IR) and optical rotary dispersion (ORD) data. ORD showed the presence of about 13% α-helical and 20% β-structures. IR absorption showed the proteins, when in the solid state, to be largely in the β-conformation. Associations take place between some of the proteins, as shown by electrophoresis and light scattering, but tyrosyl-, tryptophanyl- and phenylalanyl-residues are not involved in such associations. © 1979.