Abstract
Citrulline ia accumulated up to 0.3 M in wild watermelon leaves and functions as a hydroxyl radical scavenger under drought condition.However, the mechanism of the accumulation is unclear.
Then, we analyzed glutamate acetyltransferase (GAT) which catalyzes the first and fifth steps of citrulline biosythesis simultaneously.
The purified GAT enzyme was composed of two different kinds of peptides, of about 28 kDa.The N-terminal sequence of each peptide was homologous to the 37th to 49th and the 249th to 283rd residues of the GAT homolog from Arabidopsis thaliana.In yeast and Bucillus, a single chain precursor protein of GAT is self-cleaved leading to form the active heterotetrameric molecule.We are now analyzing the regulation in catalysis of this enzyme.
