Daily rhythm of nuclear protein kinase activity in rat liver

Daily changes of protein synthesis and secretion rates in rat liver slices

The rates of protein synthesis and secretion in rat liver slices showed temporal variability, as assessed by the use of [14C]leucine. The protein synthesis showed daily changes with two maxima at 13:00 and 01:00 hr and minimum at 17:00 hr. The secretion rate also varies within 24 hr showing biphasic pattern. The pattern of daily secretion rate for hydrophobic proteins differed from the pattern observed for acid proteins and glycoproteins.

Temporal changes of acid phosphatase, arylsulphatase, beta-galactosidase and beta-N-acetyl-D-glucosaminidase activities in subcellular fractions of rat liver

In this paper circadian changes in the liver enzyme activities of rat housed under highly standardized conditions with 12: 12 hour light-dark cycle are shown. Activities of acid phosphatase, arylsulphatase, beta-galactosidase and beta-N-acetyl-D-glucosaminidase in microsomal and lysosomal fractions and crude homogenate were estimated every 4 hr during one 24-hr period. The enzyme activities were related to 1 mg of protein, 1 mg of DNA and 1 g fresh tissue. Daily changes of enzyme activities were found. In case of activity calculated per 1 mg DNA two maxima at 0500 and at 2100 hr were observed, while activity calculated per 1 mg protein showed one maximum at 0500 hr. Activity calculated per 1 g fresh tissue showed the maximum at 0500 hr for each enzyme only in microsomal fraction. As far as acrophase table is concerned for all enzymes and fractions the acrophase occurred during the night. The obtained results are discussed in relation to lysosomal enzymes synthesis process as well as different reference values.