Rampino N J
Section on Macromolecular Analysis, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892.
Biopolymers. 1991 Jul;31(8):1009-16. doi: 10.1002/bip.360310810.
Changes in conformation, length, and mobility of individual DNA molecules during agarose gel electrophoresis were measured using video micrographs obtained by epifluorescence microscopy. Globular, V-shaped, and linear conformations of DNA are found. The mobility, upon transformation from the globular to the V-shaped conformation, decreases, suggesting a collision with a gel fiber. The duration of interaction between DNA and gel fiber is proportional to the length of DNA. Hypothetically, this proportionality underlies the size separation of DNA by agarose gel electrophoresis. DNA release from the gel fiber appears to involve the movement of the arms of the V-shaped molecule around the gel fiber. Concomitant with this movement is a length reduction the degree of which is constant for DNA of various lengths in a particular buffer milieu. The luminant densitometric profiles of DNA molecules in the V conformation show maxima at the ends and apex of the V. The unequal distribution of nucleotides along the DNA chain appears to provide the driving force for the molecular movement around the gel fiber.
利用落射荧光显微镜获得的视频显微照片，测量了琼脂糖凝胶电泳过程中单个DNA分子的构象、长度和迁移率。发现了DNA的球状、V形和线性构象。从球状构象转变为V形构象时，迁移率降低，这表明与凝胶纤维发生了碰撞。DNA与凝胶纤维之间的相互作用持续时间与DNA的长度成正比。假设这种比例关系是琼脂糖凝胶电泳分离DNA大小的基础。DNA从凝胶纤维中释放似乎涉及V形分子的臂围绕凝胶纤维的移动。伴随这种移动的是长度缩短，在特定缓冲液环境中，不同长度的DNA缩短程度是恒定的。V构象的DNA分子的发光密度测定图谱在V的末端和顶点处显示出最大值。核苷酸沿DNA链的不均匀分布似乎为围绕凝胶纤维的分子运动提供了驱动力。
