翻译一篇生物英文论文Molecular Structure of Deoxypentose Nucleic Acids

翻译一篇生物英文论文
Molecular Structure of Deoxypentose Nucleic Acids
While the biological properties of deoxypentose nucleic acid suggest a molecular structure containing great complexity, X-ray diffraction studies described here show the basic molecular configuration has great simplicity. The purpose of this communication is to describe, in a preliminary way, some of the experimental evidence for the polynucleotide chain configuration being helical , and existing in this form when in the natural state. A fuller account of the work will be published shortly.
The structure of deoxypentose nucleic acid is the same in all species (although the nitrogen base ratios alter considerably)in nucleoprotein, extracted or in cell, and in purified nucleate. The same linear group of polynucleotide chains may pack together parallel or paracrystalline material.In all cases the x-ray diffraction photograph consists of two regions, one determined largely by the regular spacing of nucleotides along the chain, and the other by the longer spacings of the chain configuration. The sequence of different nitrogen bases along the chain is not made visible.
Oriented paracrystalline deoxypentose nucleic acid (‘structure B’ in the following communication by franklin and gosling ) gives a fibre diagram as shown in fig.1 (of.ref.4). Astbury suggested that the strong 3.4-4.reflexion corresponded to the internucleotide repeat along the fibre axis. The ~34A .layer lines, however, are not due to a repeat of a polynucleotide composition, but to the chain configuration repeat, which causes strong diffraction as the nucleotide chains have higher density than the interstitial water. The absence of reflexions on or near the meridian immediately suggests a helical structure with axis parallel to fibre length .
Fig.1. Fibre diagram of deoxypentose nucleic acid from B.coli. Fibre axis vertical

脱氧戊糖核酸的分子结构
脱氧戊糖核糖生物学性质提示它的分子结构很复杂,但是这里的描述X光衍射研究表明它的基本分子结构很简单.这次交流的目的是为了初步的描述一些关于在自然状态下多核糖链结构如何以螺旋并以此方式存在的方法的实验证据.一段时间之后,关于这项工作的全面描述将会发表.
脱氧核糖核酸的结构在所有的物种中都是相同的（虽然他们的N碱基对的比例有很大的不同）,包括在细胞中或者是提取的核蛋白,和纯化的核酸中.多核酸链的线性组堆积成了平行的或者类晶体的结构.在所有的试验中,X光衍射图片包括两个部分,其中一部分由沿链均匀空间间隔排列决定,另外一个则取决于整个链的空间构象中的更长空间间隔排布.不同N碱基对的排列是看不见的.
定向类晶体脱氧核糖核酸（在下面的交流被franklin 和gosling 称为结构B)给出了纤维的图像（显示于图像1中）ASTBURY认为3.4-4中的反折与与沿纤维轴方向排列的核糖与沿纤维轴方向排列的核糖相一致.但是34A中的层次线不是因为多核糖排列造成的,而是与链的空间排列所决定的,因为核糖链要比间质水密度大的多,这样将会出现强的衍射.在经络线没有反折表明它是一个与纤维长相平行的螺旋结构
图像1.脱氧核糖核酸的显微图像,来自B.coli