Half-life of ubiquinone and plastoquinone in spinach cells

The half-life of plastoquinone (PQ), ubiquinone-9 (UQ-9) and ubiquinone-10 (UQ-10) in spinach tissue was determined. This was achieved by monitoring t he decay of radioactivity incorporated into these lipids from a labeled pre cursor. The half-life of PQ was 15 h while for UQ-9 and UQ-10 it was longer , i.e. 30 h. The values of half-lives of PQ and UQ suggest a high rate of t urnover of these lipids in spinach cells. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.