Surface complementarity, noncovalent

The pr e-Woodwardhn era largely concerned itself with the collection and classification of synthetic tools chemical reactions suited to broad application to the constitutional construction of molecular skeletons (including Kiliani s chain-extension of aldoses, reactions of the aldol type, and cycloadditions of the Diels-Alder type). The pre- Woodwardian era is dominated by two synthetic chemists Emil Fischer and Robert Robinson. Emil Fischer was emphasizing the importance of synthetic chemistry in biology as early as 1907 [30]. He was probably the first to make productive use of the three-dimensional structures of organic molecules, in the interpretation of isomerism phenomena in carbohydrates with the aid of the Van t Hoff and Le Bel tetrahedron model (cf. family tree of aldoses in Scheme 1-6), and in the explanation of the action of an enzyme on a substrate, which assumes that the complementarily fitting surfaces of the mutually dependent partners are noncovalently bound for a little while to one another (shape complementarity) [31],... 

The substrate can bind to the enzyme at the active site via noncovalent interactions (van der Waals, electrostatic, hydrogen bonding, hydrophobic), and with a specific geometric complementarity, as the surface of the active site of that enzyme is complementary in shape to the substrate. Electronic complementarities are due to the fact that the amino acid residues at the active site are arranged to interact specifically with the substrate. Although most enzymes are amino acids with hundreds of acids in the chain, the active site is the size of the substrate. Complementarity in the structure and charge between the enzyme and the substrate is illustrated by the so-called lock-and-key concept (Figure 2.15). 

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