THE EFFECT OF LIGHT ON CARBONIC-ANHYDRASE ACTIVITY OF PEA THYLAKOIDS

Carbonic anhydrase activity of pea thylakoids (tCA) was inhibited by f ar-red light under the conditions when more intensive red light does n ot affect this activity. However, DCMU-pretreatment of the thylakoids led to stimulation of tCA activity in response to far-red illumination . Effect of full red light on tCA, which could be either inhibitory or omitted, was in any case insensitive to DCMU pretreatment. The DCMU-d ependent stimulation of the thylakoid CA activity by far-red illuminat ion declined in the presence of Gramicidin D, but did not increased in the presence of phenasinmetosulphate. The possible regulation of tCA activity by a PSII component which participates in cyclic electron tra nsfer in PSII is discussed.