Chapter 4: The Reversibility of Reactions

While enzymes are an essential component of living systems, the application of reductionism whereby an enzyme is isolated (or cloned) and studied in isolation under perceived optimal conditions may not be biologically relevant. The use of enzymes under abnormal conditions can lead to a range of different reactions being facilitated and this is illustrated by the use of enzymes to carry out reverse hydrolytic reactions. Two examples are considered – the manipulation of DNA and the reaction of glucosinolates in low water systems. This leads to a more general discussion of the principles of reversibility, expectation and free will. The question then arises as to the extent to which biosynthetic pathways can be considered to be a philosophically ‘emergent’ system. The chapter concludes with a consideration and comparison of knowledge and experience and the principles of correlation and causality.