Nuclear‐Magnetic Resonance and Optical‐Spectroscopic Studies of Conformation and Interactions in the Cleaved Halves of Histone F2B

Abstract

In a previous study it was proposed that salt‐induced intrachain and interchain interactions in histone F2B were located largely in the carboxyl half of the molecule. To confirm this proposal F2B was cleaved at the methionines 59 and 62 to give the two halves of the molecule. Optical rotatory dispersion studies show that the induced secondary conformation is located entirely in the carboxyl half of the molecule and that the amino half of the molecule remains in the random coil from at all ionic strengths. Nuclear magnetic resonance studies show that the residues whose mobilities are restricted by the secondary conformation and interchain interactions lie between 66 and 102 in the carboxyl half. Although the amino half of the molecule remains in the random coil conformation throughout the range of ionic strengths 0 to 2.5 M NaCl, between 1.5 and 2.5 M NaCl nuclear magnetic resonance studies show that interchain interactions take place in the segment 30 to 50. The behaviour of the whole molecule is the average of the behaviours of its constituent halves showing that the different sections of the molecule are probably functionally independent. Copyright © 1972, Wiley Blackwell. All rights reserved