ID 4.99.1.10 DE magnesium dechelatase. AN Mg-dechelatase. CA (1) chlorophyll a + 2 H(+) = Mg(2+) + pheophytin a. CA (2) chlorophyllide a + 2 H(+) = Mg(2+) + pheophorbide a. CC -!- SGR has very low activity with chlorophyllide a and none with CC chlorophyll b. CC -!- It acts on chlorophyll a both in its free form and in protein CC complex. CC -!- SGRL, on the other hand, is more active with chlorophyllide a than CC with chlorophyll a. CC -!- The magnesium formed is scavenged by MCS (metal-chelating substance). DR O82741, SGR1_ARATH ; Q66WT5, SGR2_ARATH ; Q94AQ9, SGRL_ARATH ; //