Isopycnic centrifugation of sheared chromatin in metrizamide gradients.

摘要: Much information basic to the understanding of fundamental processes in cell biology can be obtained by studies structure, composition and properties interphase chromosomes. For a number reasons, isopycnic sedimentation chromatin suitable medium might appear offer good approach developing reproducible method purifying, possibly fractionating, this complex material. However, are such that is not easy find. Chromatin will band isopycnically CsCl [ 11, but only after fixation with formaldehyde since high concentrations salt rapidly dissociate nucleoproteins [2]. Unfortunately, reaction irreversible material so fractionated little use for further study. does sucrose gradients, very dense sucrose-glucose gradients [3]. These viscous unsheared (s~~,~ 30000 80000) sedimented through them reasonable time. This would militate against any fractionation which depends on being sheared extensively [4,5] . chloral hydrate [6], these also difficult handle may have same disadvantage as gradients. The recent report metrizamide banding unfused ribonucleoprotein particles [7] immediately suggested fractionating chromatin. paper reports preliminary formation density solutions