The influence of post-mortem conditions on the solubilities of muscle proteins

ULTRASONIC VIBRATIONS AND MICROSOMES 201 4. The activity of ultrasonically treated micro- somes could not be restored by polyuridylic acid.5. The application of ultrasonic vibrations on microsomes caused a several-fold increase in phosphodiesterase activity as measured by the breakdown of [8H]polyuridylic acid.As a break- down product, an increased amount of 5'-UMP was obtained.There was no significant effect on the breakdown by ultrasonically treated ribonucleo- protein particles.6. Electron microscopy showed that on treat- ment by ultrasonic vibrations the microsomal fraction retained membranes and particles.No apparent change in the structure of isolated ribonucleoprotein particles was observed.The membrane-bound enzyme glucose 6-phosphatase was not destroyed by treatment with ultrasonic vibrations for 1 min.We thank Professor F. Dickens, F.R.S., for his interest