An open reading frame with fatty acid desaturase similarity was identified in the genome ofTrypanosoma 1224 bp sequence specifies a proteinof 408 amino acids with 59% and 58% similarity toMortierella alpinaandArabid-opsis thalianaD12 desaturase, respectively, and 51% with A. thalianax3 desaturases. The histidine tracks that com-pose the iron-binding active centers of the enzyme were more similar to those of thex3 desaturases.