Incorporation of [¹⁴C]-glutamate into proteins and chlorophylls in Dunaliella tertiolecta, a marine chlorophyte

Incorporation of [¹⁴C]-glutamate into soluble proteins accounted for about 14% of the total glutamate uptake, while < 1% of the ammo acid carbon was incorporated into chlorophyll a. Most of the remaining 85% of the glutamate was retained in low molecular mass pools. High uptake rates appeared to be related to a "shift-up" phenomenon, resulting from the addition of fresh media. Apparent turnover times, estimated from reverse isotope dilution experiments, varied from about 1 to 3.5 h for the soluble proteins and about 3 to 5 h for chlorophyll a. Rapid changes in glutamate to glutamine ratios, resulting from changes in irradiance, suggest that the intermediary metabolism of glutamate is regulated by irradiance.