DEGRADATION OF HISTONES DURING MANIPULATION OFISOLATED NUCLEI AND DEOXYRIBONUCLEOPROTEIN

1. 1. Incubation of isolated nuclei or deoxyribonucleoprotein for an hour at 37° in a neutral medium generated new components at the expense of the authentic histones. The amino acid composition of these artifacts indicated that they were derived from authentic histone, and their relative electrophoretic mobilities in polyacrylamide gels showed that they were somewhat smaller than the authentic histone. N-Terminal analysis confirmed that proteolysis occurred during the incubation which produced the artifacts. 2. 2. Many degradation products could be resolved from authentic histones electrophoretically or chromatographically, but all the resolving systems tried (perhaps except one) failed in one case or another to resolve some artifacts. The chromatographic behavior of the degradation products which were resolved resembled components normally found in histone preparations derived from rapid, strong-acid extraction. 3. 3. It was concluded that many degradation products could easily escape detection, and that those which were resolved could easily be mistaken for endogenous histones since they fit the general definition of histone very well. © 1968.