Protein carboxymethylation during in vitro culture of human peripheral blood monocytes and pulmonary alveolar macrophages.
Protein carboxymethylase (PCM) activity was evaluated for long-term in vitro cultures of human peripheral blood monocytes and pulmonary alveolar macrophages. Both cell types exhibited increases in endogenous (without addition of the exogenous substrate, gelatin) and total (with gelatin) enzyme activity with increased time in culture. Monocytes developed increased activity after a 5-day lag period; three-to four-fold increases over day 1 values in both total and endogenous specific activity occurred. In contrast, PCM activity increased for pulmonary alveolar macrophage (PAM) without a detectable lag period. Although the increase in endogenous activity of 10--14-day PAM culture was similar to comparable age monocyte cultures, total enzyme activity increased only two-fold above day 1 values. The observation of changes in PCM endogenous specific activity in monocyte cultures may reflect alterations in enzyme activity and/or levels of endogenous methyl-acceptor proteins.
D002478:Cells, Cultured; D005780:Gelatin / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008264:Macrophages / Q000201:enzymology*; D008745:Methylation; D009000:Monocytes / Q000201:enzymology*; D011496:Protein Methyltransferases / Q000378:metabolism*; D011497:Protein O-Methyltransferase / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000166:cytology; D013997:Time Factors
D005780:Gelatin; D011496:Protein Methyltransferases; D011497:Protein O-Methyltransferase