ISHS Acta Horticulturae 553: IV International Conference on Postharvest Science
MECHANISM OF CARBON DIOXIDE ACTIVATION OF 1-AMINOCYCLOPROPANE-1-CARBOXYLATE (ACC) OXIDASE |
| Authors: | D.R. Dilley, D.K. Kadyrzhanova, Z. Wang |
| Keywords: | ethylene, site-directed mutations, fusion proteins, ascorbic acid. |
| Abstract:
ACC oxidase (ACCO) catalyzes the final step in ethylene biosynthesis. ACCO requires ascorbic acid, bicarbonate, ferrous ion and dioxygen for activity. His177, Asp179 and His234 in ACCO are ligands for iron (Kadyrzhanova et al., 1999; Shaw et al., 1996). These His and Asp residues comprise a 2-His-1-Asp facial triad common to other mononuclear non-heme iron (II) enzymes. Fe(II) is the dioxygen binding site and the ACC amino group is an iron ligand (Rocklin et al., 1999). To determine the nature and role of other conserved amino acid residues important for conversion of ACC to ethylene and for CO2 activation, native and mutant ACCOs were expressed in Escherichia coli as His-Tag fusion proteins, purified and enzyme kinetics determined. | |
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