【摘要】 <正> 绘制DNA物理图谱,对于DNA的分子克隆,基因定位,核酸序列的测定及进化比较等方面的研究都有一定意义。本文初步探讨了DNA物理图谱绘制中的某些问题:酶的选择,双酶解的组合方案,双酶解的局限性,以及部分降解最多区带公式。更多还原

【Abstract】 Suppose the number of nucleotides recognized by a certain restriction enzyme is S, the frequency for the recognition sites of this enzyme to be found in a DNA will be F=1/4S, the average length of the fragments produced by its digestion will be L=1/F, and then in a DNA consisted of nucleotides, the number of sites that can be cut by this enzyme will be Q = m/L. This paper proposed a standard combination programming for making the physical map of a DNA if the method of double enzyme digestion is used, and deduced a formula to evaluate the number of all possible standard combinations, R = 2M-3(M represents the kinds of enzymes used). Some limitations in using the method of double enzyme digestion were discussed. Two other formulas for calculation of the maximum number of partial digestion bands were also established: one, Zcir = W2-W+1, can be used for circular DNA, the other, Zlin = W(W + l)/2, for linear DNA(W represents the number of fragments produced by a complete enzyme digestion, Z the maximum number of bands).更多还原