## Method

A DNA walk of a genome represents how the frequency of each nucleotide of a pairing nucleotide couple changes locally. This analysis implies measurement of the local distribution of Gs in the content of GC and of Ts in the content of TA as proposed by Lobry (1996 , 1999). We have used the Z curve(Zhang & Zhang,2003) method to plot Genome landscape of an Archaea. Z curve has three axis X axis represent excess of Purine vs Pyrimidin, Y axis represent excess of Amino vs keto and Z axis represent excess of Weak vs Strong Hydrogen bonds. The three components of the Z curve, Xn, Yn and Zn, represent three independent distributions that completely describe the DNA sequence being studied, where, the X-component of a Z curve Xn displays the distribution of purine/pyrimidine (R/Y) bases along the sequence; the Y-component of a Z curve yn displays the distribution of amino/keto (M/K) bases along the sequence; the Z-component of a Z curve Zn displays the distribution of strong-H bond/weak-H bond (S/W) bases along the sequence. For the subsequence constituted from the 1st base to the n-th bases of the sequence, when purine bases (A or G) are in excess of pyrimidine bases (C or T), Xn >0, otherwise, Xn<0. When the numbers of purine (A or G) and pyrimidine bases (C or T) are identical, Xn =0. When bases (A or C) are in excess of keto bases (G or T), Yn>0, otherwise, Yn<0. When the numbers of amino (A or C) and keto bases (C or T) are identical, Yn=0. When weak H- bond bases (A or T) are in excess of strong H-bond bases (G or C), Zn>0, otherwise, Zn<0. When the numbers of weak H-bond (A or T) and strong H-bond bases (G or C) are identical, Zn=0.