semialdehyde

sem·i·al·de·hyde

(sem'ē-al'dĕ-hīd), The monoaldehyde of a dicarboxylic acid, so called because half the COOH groups of the original acid are reduced to the aldehyde, whereas the other half are unchanged, for example, glutamic acid γ-semialdehyde, OHC-CH2CH2CH(NH3)+-COO-. Many semialdehydes are intermediates in the biosynthesis and metabolic degradation of amino acid, for example, l-proline, l-lysine, l-glutamate.