The optical rotatory properties of the beta-configuration in polypeptides and proteins.

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Abstract
Poly-L-lysine and an L-tyrosine copolymer have been converted to [beta]-form by heating In alkaline solutions. Aggregation is suppressible, and the product appears to consist of single molecules in planar, folded configurations producing the antiparallel chain arrangments. This form has a trough at 230 m[mu] (m[image] = [long dash]6400), a peak at 205 m[mu] (m[image] =+22,000) in the ORD [optical rotatory dispersion], and a trough at 218 m[mu] ([theta] =[long dash]23,000) in the CD [circular dlchrolsm]. A similar configuration is produced at neutral pH with the addition of sodium dodecyl sulfate. Here the trough is more shallow, presumably ecause of solvent perturbation on the n-[pi] * transitloa Outside the absorption band the ORD is characterized by a0 = [long dash]340, b0 = -152 for the alkaline solution form, and by a0 =174 and bo [long dash]9 for the form in detergent solution. Several proteins are shown to have ORD and CD spectra very similar to that expected for certain proportions of [beta]-form and disordered soil. Here the fit in the 230 region is better with the constants of the sodium dodecyl sulfate-produced [beta]-form.