Presence of a protein methylesterase in mammalian tissues.

Using enzymatically methylated protein-³H methyl esters as substrates, a protein methylesterase activity was observed in mammalian tissues. The product of hydrolysis was identified as radioactive methanol by microdistillation under reduced pressure and formation of a 3,5-dinitrobenzoate derivative. The enzyme was active over a broad range of pH and appeared in all tissues investigated. Since protein carboxyl-methylation is involved in chemotaxis of leukocytes and exocytotic secretion, this protein methylesterase probably participates in the regulation of these processes.