Fig. 3.

Peptides in heart mitochondria turn over more slowly than in liver mitochondria. A, The percentage of newly synthesized peptide is plotted over time for all peptides of superoxide dismutase 2 (SOD2, Swiss-Prot P09671) that were detected in the mice liver and heart mitochondria samples. The solid lines indicate the calculated synthesis curves. The dotted lines indicate the 95% confidence interval. Thirteen peptides unique to SOD2 were detected from the heart samples and nine unique peptides were detected from the liver samples. There were 39 and 76 data points with a unique peptide and time point in liver and heart samples, respectively. The decay rate of SOD2 was 0.158 day⁻¹ in liver mitochondria and 0.026 day⁻¹ in heart mitochondria. B, A histogram is plotted of the log₂ of the ratio of the first-order rate constants for proteins detected in both the liver and heart mitochondria samples. Proteins were filtered to those with a minimum of seven time points.