Multifractal characterisation of length sequences of coding and noncoding segments in a complete genome

The coding and noncoding length sequences constructed from a complete genom e are characterised by multifractal analysis. The dimension spectrum D-q an d its derivative, the 'analogous' specific heat C-q are calculated for the coding and noncoding length sequences of bacteria, where q is the moment or der of the partition sum of the sequences. From the shape of the D-q and C- q curves, it is seen that there exists a clear difference between the codin g/noncoding length sequences of all organisms considered and a completely r andom sequence. The complexity of noncoding length sequences is higher than that of coding length sequences for bacteria. Almost all D-q curves for co ding length sequences are flat, so their multifractality is small whereas a lmost all D-q curves for noncoding length sequences are multifractal-like. It is seen that the 'analogous' specific heats of noncoding length sequence s of bacteria have a rich variety of behaviour which is much more complex t han that of coding length sequences. We propose to characterise the bacteri a according to the types of the C-q curves of their noncoding length sequen ces. This new type of classification allows a better understanding of the r elationship among bacteria at the global gene level instead of nucleotide s equence level. (C) 2001 Elsevier Science B.V. All rights reserved.