Adenylate energy charge, phosphorylation

Walesby, N.J. and Johnston, I.A. (1980). Temperature acclimation in brook trout muscle adenine nucleotide concentrations, phosphorylation state and adenylate energy charge. Journal of Comparative Physiology 139B, 127-133. 

To determine how the rate of phosphorylation and the inactivation of carboxylase respond to the adenylate energy charge (7), phosphorylation and inactivation of the carboxylase in the presence of different adenylate energy charge systems were examined as shown in Fig. 11. In this experiment, the effects of different concentrations of ATP alone, and different energy charge systems composed of AMP and ATP, on the... 

Fig. 11. Response of inactivation of acetyl-CoA carboxylase to the adenylate energy charge. Acetyl-CoA carboxylase-protein kinase preparation was preincubated as described in Fig. 1 at 37°C for 30 minutes except without AMP. Following this preincubation, inactivation and phosphorylation of the carboxylase were measured by determining the carboxylase activity remaining after incubation for 4 minutes in the presence of different adenylate energy charge systems containing ATP and AMP, or ATP alone as indicated. Carboxylase was then assayed in the presence of a final concentration of 10...

The effect of the adenylate energy charge on the phosphorylation of the enzyme is shown in Fig. 12. The degree of phosphorylation is inversely correlated with the degree of enzyme inactivation, indicating that the different levels of enzyme inactivation are due to phosphorylation of the carboxylase. The inactivation rates in the presence of differ-... 

When cyclic AMP was substituted for AMP in the adenylate energy charge system, cyclic AMP affected the inactivation of carboxylase in a manner similar to AMP (132). Since the phosphorylation and inactivation system contains no activity which degrades cyclic AMP, the effect of cyclic AMP is not the result of degradation of cyclic AMP to AMP by phosphodiesterase (130). 

Upon illumination the ATP content in Chi. fusca cell increased significantly while the AMP content decreased. The phosphorylation rate during the first 30 seconds varied in parallel experiments between 5.8 and 7.7 nmoles ATP/10° cells h. During the next 5 minutes of illumination the ATP content did not increase further (Fig. 1, table 1). The adenylate energy charge rose from 0.55 at the end of dark adaptation to 0.75 after 30 seconds of illumination and then decreased to 0.69 after 5 minutes in the light (Fig. 2). 

Active fish have a better developed capillary system in the red muscle to supply oxygen to the mitochondria, and a higher haematocrit (Blaxter et al., 1971). The red muscle tissue also contains more cytochromes (respiratory proteins), and exhibits more cytochrome oxidase activity, which is responsible for transferring electrons in die respiratory chain, more efficient respiration control (oxidative phosphorylation and P/O coefficient) and a greater Atkinson charge, which characterizes energy reserve accumulated in adenyl nucleotides ... 

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