Juswinder Singh1, Janet M. Thornton1
1Laboratory of Molecular Biology, Crystallography Department, Birkbeck College, Malet Street, London WC1E 7HX, England
Tóm tắt
An analysis has been made of the geometry of phenylalanine‐phenylalanine interactions in proteins of known structure. 162 Phe‐Phe interactions were found with C‐C distances less than 4.6 Å. Three angles were used to define the geometry of interaction, P = the angle betwen ring planes, and polar coordinates, Tθ, Tϕ to specify the relative spatial disposition of the two rings. The overall distribution of P values is the same as that expected for a random distribution of planes in 3 dimensions; i.e. the majority, of interactions have P approaching 90°. However, for high Tθ values (when one Phe lies directly above the ring of the other Phe) the distribution is non‐random, and a preference for perpendicular interactions is expressed. This preference is in accord with recent quantum‐mechanical calculations.
