A FURTHER EXAMINATION OF THE MOLECULAR WEIGHT AND SIZE OF DESOXYPENTOSE NUCLEIC ACID
A FURTHER EXAMINATION OF THE MOLECULAR WEIGHT AND SIZE OF DESOXYPENTOSE NUCLEIC ACID
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DOI：
10.1021/ja01640a067
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发表时间：
1954-01-01
影响因子：
15
通讯作者：
DOTY, P
中科院分区：
文献类型：
--
作者：
REICHMANN, ME;RICE, SA;DOTY, P
对小牛胸腺脱氧戊糖核酸钠（DNA）新样品进行了光散射和低梯度粘度法研究。这些与早期的测量解释的基础上，新的值为特定的折射率增量和消光系数。结果表明，精心制备的DNA样品的重均分子量约为600万，分子形状类似于刚性螺旋，其均方根端到端间距为5000 A。其轮廓长度为20，000 A。以下证据证实了这些发现：（1）由Mandelkern和Flory的沉降常数-特性粘度公式计算的分子量，（2）由Flory-Fox方程计算的端-端分离，（3）螺旋的旋转扩散常数与特性粘度之间符合Riseman-Kirkwood关系，（4）由R. C.威廉姆斯。如果特性粘数和旋转扩散常数用旋转椭球体来解释，而没有水合作用，则轴比在400 ~ 500范围内，但这些值的字面解释必须被拒绝。本实验室以前的通讯4· 6已经讨论了从小牛胸腺中提取的脱氧核糖核酸钠（DNA）的分子量、大小和形状。我们希望在这里报告对特别感兴趣的进一步样品的测量，以稍微修改我们先前的分子测量结果。
Light scattering and low gradient viscometric studies of new sodium desoxypentose nucleate (DNA) samples from calf thymus have been carried out. These together with earlier measurements are interpreted on the basis of new values for the specific refractive index increment and the extinction coefficient. It is concluded thatcarefully prepared samples of DNA have a weight average molecular weight of about six million and a molecular shape resembling a stiff coil whose root-mean-square end-to-end separation is 5000 A. and whose contour length is 20,000 A. The following evidence corroborates these findings:(1) The molecular weight calculated iron the sedimentation constant-intrinisc viscosity formula of Mandelkern and Flory,(2) the end-to-end separation calculated from the Flory-Fox equation,(3) the agreement with the Riseman-Kirkwood relation between rotary diffusion constant and intrinsic viscosity for coils and (4) preliminary electron micro-scope studies by R. C. Williams. If intrinsic viscosity and rotary diffusion constants are interpreted in terms of an ellipsoid of revolution with no hydration axial ratios in the range of 400 to 500 are obtained but the literal interpretation of these values must be rejected.Previous communications from this Laboratory4· 6 have dealt with the molecular weight, size and shape of four preparations of sodium desoxyribonucleate (DNA) from calf thymus. We wish to report here on the measurement of further samples of particular interest, to revise slightly our earlier molecular