title: Human placenta S-adenosylmethionine: protein carboxyl O-methyltransferase (protein methylase II). Purification and characterization.
abstract: 1. Protein methylase II was purified from human placenta approx. 8700-fold with a yield of 14%. 2. Unlike protein methylase II from other sources, the activity of human placenta enzyme was completely inhibited by 2 mM Cu2+. Other divalent ions were without effect. 3. Human chorionic gonadotropin (HCG), immunoglobulin A and calf thymus histones served as good in vitro substrates for the enzyme, particularly HCG. 4. The Km for S-adenosyl-L-methionine and Ki for S-adenosyl-L-homocysteine were 2.08 x 10(-6) and 5.8 x 10(-7) M, respectively. 5. The protein methylase II activity in human placenta changed with gestational age, the activity at 1st and 2nd trimester being approximately twice that of term placenta.
authors.affiliation: Department of Biochemistry, Won-Kwang University, College of Medicine, Chulia-Bukdo, Korea.
authors.forename: M K
authors.initials: MK
authors.lastname: Paik
authors.forename: B D
authors.initials: BD
authors.lastname: Hwang
authors.forename: K
authors.initials: K
authors.lastname: Lim
mesh_terms: D002413:Cations, Divalent; D003300:Copper / Q000494:pharmacology; D005260:Female; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism; D008745:Methylation; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011496:Protein Methyltransferases / Q000302:isolation & purification*; D011497:Protein O-Methyltransferase / Q000037:antagonists & inhibitors / Q000302:isolation & purification*; D013379:Substrate Specificity
chemical_list: D002413:Cations, Divalent; D008565:Membrane Proteins; D003300:Copper; D011496:Protein Methyltransferases; D011497:Protein O-Methyltransferase