1. The stereospecificity of 20 enzymes from plants is reported. 2. The stereospecificity of all known forms of malate dehydrogenase in plants and animals has been shown to be A-specific. 3. The generalization that ‘the stereospecificity of a particular reaction is independent of the source of the enzyme’ is confirmed for a total of 12 plant enzymes. 4. A new generalization is proposed: ‘When a metabolic sequence involves consecutive nicotinamide–adenine dinucleotide-dependent reactions, the dehydrogenases have the same stereospecificity.’
