Affinity chromatography in the study of macromolecular interactions: I. binding of DNA to immobilized histones II. interaction of two nonhistone chromosomal proteins with H1 histone and its subfractions immobilized on agarose

Part I The six major histone fractions of chicken erythrocytes have been individually immobilized on agarose. The binding of native and denatured DNA to these immobilized histones was studied. It was found that the binding efficiency of various immobilized histone fractions for native DNA decreases in the order of: H5, H1, H2B=H3, H4)H2A; which is in good agreement with previous results obtained using free solution techniques. Denatured DNA bound to the hlstone-agarose anomalously, giving a tight complex which was not dissociated by 2 M NaCl. Part II The interaction of calf thymus H1 histones with two calf thymus nonhistone proteins, HMG1 and HMG2, (High Mobility Group proteins, Walker et al., Eur. J. Biochem. 62. 461, 197^) has been studied using columns of H1 immobilized on agarose. HMG2 does not interact with immobilized H1, but HMG1 binds to H1 columns at low ionic strength and can be eluted with NaCl in the range of O.Of to 0.1 J M. Three chromatographic subfractions of H1 have also been immobilized and tested for their ability to bind HMG1. Based on the NaCl concentration required to elute HMG1 from the H1 subfraction columns, it is found that affinity of the H1 subfractions for HMG1 is 2>1>3.