Senior M B, Olins D E
Biochemistry. 1975 Jul 29;14(15):3332-7. doi: 10.1021/bi00686a007.
Formaldehyde (HCHO) fixation of chicken erythrocyte chromatin produces a marked decrease in its positive circular dichroism (CD), above 260 nm, and the appearance of s small negative ellipticity around 295 nm. The ultraviolet spectrum of chromatin is unaffected, nor does HCHO produce any changes in the uv or CD spectra of chicken erythrocyte DNA. The extent of the circular dichroism transition from the native chromatin to the suppressed spectrum is dependent on the concentration of HCHO and salt concentration. The kinetics of the reactions are complex, implicating at least two reactive species. Studies of the reaction of HCHO with chromatin in ethylene glycol and CD measurements of aqueous chromatin solution with added glutaraldehyde preclude simple dehydration and general cross-linking effects as causes of the CD changes observed. The results are interpreted as indicating a conformational change of the DNA in chromatin caused by histone-DNA or histone-histone cross-linking.
用甲醛（HCHO）固定鸡红细胞染色质会使其在260nm以上的正圆二色性（CD）显著降低，并在295nm左右出现一个小的负椭圆率。染色质的紫外光谱不受影响，HCHO也不会使鸡红细胞DNA的紫外或CD光谱发生任何变化。从天然染色质到受抑制光谱的圆二色性转变程度取决于HCHO的浓度和盐浓度。反应动力学很复杂，涉及至少两种反应物种。对HCHO与乙二醇中染色质反应的研究以及对添加戊二醛的染色质水溶液的CD测量排除了简单脱水和一般交联效应是观察到的CD变化的原因。结果被解释为表明染色质中DNA的构象变化是由组蛋白-DNA或组蛋白-组蛋白交联引起的。
