title: NCC malonyltransferase catalyses the final step of chlorophyll breakdown in rape (Brassica napus).
abstract: Of the three final products of chlorophyll breakdown that in senescing cotyledons of oilseed rape are accumulated progressively, the nonfluorescent Bn-NCC-1 is the most abundant catabolite. It represents the malonylester of the minor catabolite Bn-NCC-3. The in vitro malonylation of Bn-NCC-3 into Bn-NCC-1 was investigated. Extracts from senescent as well as from presenescent cotyledons contained corresponding activities in the presence of malonyl-coenzyme A as the co-substrate. Malonyltransferase activity exhibited pH- and activation optima at 8 and 34 degrees, respectively, and it was saturable with an apparent Michaelis constant of 58 microM for Bn-NCC-3. The partially purified enzyme recognized chlorophyll catabolites as substrate specifically, provided that they had a free hydroxyl group in the ethyl side chain of pyrrole B.
authors.affiliation: Department of Plant Biology, University of Zürich, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Hörtensteiner
mesh_terms: D051080:Acyl-Carrier Protein S-Malonyltransferase; D000217:Acyltransferases / Q000378:metabolism*; D001937:Brassica / Q000201:enzymology / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D002734:Chlorophyll; D000217:Acyltransferases; D051080:Acyl-Carrier Protein S-Malonyltransferase