Statistical properties of nucleotide clusters in DNA sequences.

Using the complete genome of Plasmodium falciparum 3D7 which has 14 chromosomes as an example, we have examined the distribution functions for the amount of C or G and A or T consecutively and non-overlapping blocks of m bases in this system. The function P(S) about the number of the consecutive C-G or A-T content cluster conforms to the relation P(S) proportional, variante(-alphas); values of the scaling exponent alpha(CG) are much larger than alpha(AT); and alpha(AT) of 14 chromosomes are hardly changed, whereas alpha(CG) of 14 chromosomes have a number of fluctuations. We found maximum value of A-T cluster size is much larger than C-G, which implies the existence of large A-T cluster. Our study of the width function xi(m) of cluster C-G content showed that follows good power law xi(m) proportional, variantm(-gamma). The average gamma for 14 chromosomes is 0.931. These investigations provide some insight into the nucleotide clusters of DNA sequences, and help us understand other properties of DNA sequences.