title: Purification and properties of a ribosomal protein methylase from Eschericha coli Q13.
abstract: Ribosomal protein methylase has been purified from Escherichia coli strain Q13 using methyl-deficient 50S subunits as substrates. The purified enzyme (or enzyme complex) which is devoid of rRNA methylating activity is quite stable and has a pH optimum around 8.0. The Km for S-adenosyl-L-methionine is 3.2 muM. The molecular weight of the enzyme is 3.1 X 10(4); minor methylating activity was also detected for protein peaks with molecular weights of 1.7 X 10(4) and 5.6 X 10(4). Protein L11 is the major protein methylated by the purified enzyme. Product analysis revealed the presence of N epislon-trimethyllysine, a methylated neutral amino acid(s) previously observed in protein L11 and N epislon-monomethyllysine. Free ribosomal proteins were much better substrates for the methylation, indicating that methylation of 50S ribosomal proteins can occur before the complete assembly of the 50S ribosomal subunit.
mesh_terms: D004926:Escherichia coli / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008780:Methyltransferases / Q000302:isolation & purification* / Q000378:metabolism; D008970:Molecular Weight; D012269:Ribosomal Proteins / Q000032:analysis
chemical_list: D012269:Ribosomal Proteins; D008780:Methyltransferases