Biomedical subjects
Publications and source records attributed to Reginald F Cross.
The molecular radii (r) of a series of peptides have been determined by molecular modeling. With these data, it is shown that electrophoretic mobility (mu(ep)) is proportional to 1/r2, and that the dependence presented in textbooks (mu(ep) infinity 1/r) is wrong. Use of the approximately equivalent, mass-based Offord equation is discussed, and other relevant considerations are presented.
A molecular modeling package has been used to systematically hydrate a series of previously built peptides. The volume data derived have been used with the log-log form of the inverse square law and published electrophoretic mobilities to test for the most likely states of hydration. Starting with the bare peptides and increasing hydration, however, the strength of correlation diminishes, indicating that the average electromigrating peptide is not extensively hydrated. The shapes of the peptides are predominantly oblate ellipsoidal, but generally do not deviate significantly from spherical and progressive hydration increases this trend. Thus, shape correction does not play a significant role in the calculations.