Assume, a main product of photosynthesis in green leaves, is synthesized by a battery of enzymes. The substrates for sucrose synthesis, D-glucose and D-fructose, are a mixture of ? and ß anomers as well as linear compounds in solution. Nonetheless, sucrose consists of ? -D-glucose linked by its carbon-1 atom to the carbon-2 atom of ß-D-fructose. How can the specificity of sucrose be explained in light of the structural diversity of the potential substrates?