Preproceruloplasmin is a primary product of cell-free translation of ceruloplasmin messenger RNA

Effect of age on the activity of ceruloplasmin of human blood

Aminoxidase activity of ceruloplasmin was measured in the serum of 120 people (between 45 and 102 years of age) using the p-phenylenediamine method. A negative linear age-correlation (-30% for the whole lifespan; P < 0.01) was established in this activity with increasing age, nevertheless the total copper content of blood did not change in the same age-range as measured by an atomic absorption spectrophotometric method. Increasing ionic strength, in vitro, caused an exponential decline in blood ceruloplasmin aminoxidase activity of both middle aged and elderly subjects. The age-dependent decrease in ceruloplasmin activity could have a negative effect on the antioxidant functions of blood, and finally on the aging process itself.

An enzyme-linked immunoadsorbent assay for rat ceruloplasmin

A noncompetitive, colorimetric enzyme-linked immunoadsorbent assay (ELISA)+ was developed for measuring rat ceruloplasmin in serum and in medium from culture hepatocytes. The assay utilized polystyrene immobilized antibody which bound ceruloplasmin which then bound biotinylated antibody. The biotinylated antibody-antigen complex was detected with strepavidin-alkaline phosphatase conjugate. Standard curves for rat ceruloplasmin were constructed in the range between 10 and 50 ng/mL. Increases of 10 ng produced an increase in A403 of more than 0.2. With this immunoassay, serum ceruloplasmin levels were found to average 35 mg Cp/dL in control rats and 87 mg/dL in rats with experimental inflammation. Liver parenchymal cells secreted 1.6 micrograms Cp/5 x 10(5) cells/24 h. This ELISA assay for ceruloplasmin will facilitate studies on the regulation of ceruloplasmin synthesis and secretion in both intact rats and isolated hepatocytes.

Isolation of a human ceruloplasmin cDNA clone that includes the N-terminal leader sequence

A number of cDNA clones encoding human ceruloplasmin were identified using two mixed oligonucleotide probes. One of these clones was shown by DNA sequence analysis to span from the complete N-terminal leader sequence to 114 amino acids short of the C-terminus. The leader sequence consists of 19 primarily hydrophobic amino acids. Northern blot analysis of RNA from human liver showed two species of ceruloplasmin mRNA; a minor species of 3600 nucleotides and a major one of 4400 nucleotides.

Secretion of ceruloplasmin by a human clear cell carcinoma maintained in nude mice

Ceruloplasmin is the best known but least understood copper protein. Studies preliminary to investigating the control of ceruloplasmin synthesis have utilized a human renal cell carcinoma maintained in nude mice for 73 passages over a 5-year period. In vitro cultures of these cells were accomplished and the mRNAs were extracted prior to microinjection into Xenopus oocytes. The media examined by SE-HPLC and immunological techniques demonstrated that (1) after in vitro culture, ceruloplasmin was secreted as an uncleaved polypeptide chain with a MW of 135,000; (2) the translational product of ceruloplasmin mRNA injected into Xenopus oocytes was cleaved into fragments with MWs of 110,000, 67,000, and 50,000. The results indicate that mRNA for human ceruloplasmin can be obtained to serve as a template for the synthesis of a cDNA probe to investigate the control of human ceruloplasmin's synthesis.