Biochemical Systems Theory and Metabolic Control Theory: 1. Fundamental Similarities and Differences

Biochemical Systems Theorv (BST) was developed in the late 1960s to explicate the integrated behavior of intact biochemical systems-specific dynamic behavior as well as general principles of design-in relation to the properties of their underlying molecular elements. This approach was used successfully in a number of biochemical and other biological applications throughout the 1970s and 1980s. A related approach. Metabolic Control Theory (MCT), was proposed in the mid 1970s. Its developments generally have followed without reference the analogous developments in BST. and its proponents have treated the two approaches as if they were unrelated. Detailed comparison of the fundamental structures of BST and MCT shows that. although there arc some superficial differences, both in fact are based upon the same underlying formalism. Molecular descriptions in MCT comprise a special case of those in BST. Systemic descriptions differ with respect to the level of aggregation assumed. The aggregation at the level of net increase or net decrease of each system constituent found in BST is shown to produce the more revealing and useful theory, and results presented &where [41] suggest that this level of aggregation also provides a more accurate description of the system. At this fundamental level, MCT represents a special case of BST. for the content and range of validity of BST arc more inclusive than those of MCT.