Here’s the Abstract for Chapter 5 of The First Gene:
Functional Sequence Complexity in Biopolymers
Kirk K. Durston & David K.Y. Chiu
Department of computer science, Bioinformatics, University of Guelph
ABSTRACT. It is generally recognized that biopolymers such as DNA, RNA and proteins demonstrate a form of sequence complexity. Recent work has provided a more detailed insight into biopolymeric complexity by introducing three types of sequence complexity, Random Sequence Complexity (RSC), Ordered Sequence Complexity (OSC) and Functional Sequence Complexity (FSC). The primary feature of FSC that distinguishes it from RSC and OSC, is the imposition of functional controls upon the sequence. In this paper, we propose that it can be measured using an extended form of Shannon uncertainty that includes a variable of functionality. Clearly, FSC can be found in human languages and carefully designed computer code, but the measure we propose in this paper reveals that it is also found in biopolymers. In the case of proteins, the measure of FSC provides an estimate for the target size of a protein family in the amino acid sequence space, revealing that functional sequences occupyan extremely small fraction of sequence space. Due to the miniscule size of functional sequence space for a given protein family, as mutations accumulate there will be an increasing likelihood of moving the mutated sequence outside that space, with a corresponding deleterious effect on FSC.