Tyrosine Metabolism in Blowfly Larvae at Pupation

Abstract

In insects tyrosine has been regarded as participating in metabolic reactions which lead, not only to its incorporation in various proteins, but also to sclerotization of the cuticle (i.e. quinone cross-linking of cuticular protein). Three different meta-bolic pathways have been suggested, all of which lack direct evidence to support them. The suggested pathways are (i) oxidative deamination leading to the formation of o-quinones, (ii) non-specific hydroxylation and elimination of the side-chain leading to the formation of p-quinones, and (iii) conversion to N-acetyldopamine which is the phenolic precursor of the sclerotizing quinone. For a review of these theories see Pryor (1962) and Hackman (1964).