A statistical mechanical treatment of biopolymers is presented that includes the sequence information as an internal coordinate. This approach allows an assessment of the contribution of sequence information to the thermodynamic entropy. Even in cases where the sequence composition has no effect on the intersubunit interactions, the sequence composition contributes to the entropy of the system. Using a path integral representation, the canonical partition function can be represented as a product of a polymer configurational path integral and a sequence walk path integral. In most, biological instances the sequence composition influences the potential energy of intersubunit interaction. Consequently, the two path integrals are not separable, but rather "interact" via a sequence-dependent configurational potential. Biological constraints can also be built into the system and these effectively introduce an external potential. In proteins and RNA, the sequence walk occurs in dimensions greater than 3 and, therefore, will be an ideal "polymer". The Markovian nature of this walk can be exploited to show that all the structural information is contained in the sequence. This later effect is a result of the dimensionality of the sequence walk and is not necessarily a result of biological optimization of the system.
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