DIFFERENCES IN OSCILLATION FREQUENCIES BETWEEN 2 KEY ENZYMES OF AROMATIC AMINO-ACID CATABOLISM IN EUGLENA - CIRCADIAN RHYTHMICITY OF TRYPTOPHAN 2,3-DIOXYGENASE VS PREDOMINANCE OF ULTRADIAN PERIODS IN TYROSINE AMINOTRANSFERASE

In Euglena gracilis Klebs, strain Z, two key enzymes of aromatic amino acid catabolism, tryptophan 2,3-dioxygenase and tyrosine aminotransfe rase exhibit an entirely different chronobiological behaviour, indicat ing that the pathways of the respective amino acids are largely indepe ndent from a dynamical point of view. Tryptophan 2,3-dioxygease exhibi ts a pronounced circadian rhythm, whereas, under same conditions, tyro sine aminotransferase oscillates predominantly with an ultradian perio d. This difference is seen both in LD 12:12 and LL. In tyrosine aminot ransferase, circadian rhythmicity is normally either undetectable or o nly present as a weak trend; occasionally, the circadian and ultradian oscillations can attain similar amplitudes.