Glycine N-methyltransferases: a comparison of the crystal structures and kinetic properties of recombinant human, mouse and rat enzymes.
Glycine N-methyltransferases (GNMTs) from three mammalian sources were compared with respect to their crystal structures and kinetic parameters. The crystal structure for the rat enzyme was published previously. Human and mouse GNMT were expressed in Escherichia coli in order to determine their crystal structures. Mouse GNMT was crystallized in two crystal forms, a monoclinic form and a tetragonal form. Comparison of the three structures reveals subtle differences, which may relate to the different kinetic properties of the enzymes. The flexible character of several loops surrounding the active site, along with an analysis of the active site boundaries, indicates that the observed conformations of human and mouse GNMTs are more open than that of the rat enzyme. There is an increase in kcat when going from rat to mouse to human, suggesting a correlation with the increased flexibility of some structural elements of the respective enzymes.
Pakhomova
Svetlana
S
Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA.
Luka
Zigmund
Z
Grohmann
Steffi
S
Wagner
Conrad
C
Newcomer
Marcia E
ME
D000595:Amino Acid Sequence; D000818:Animals; D018360:Crystallography, X-Ray / Q000379:methods*; D050938:Glycine N-Methyltransferase; D006801:Humans; D007700:Kinetics; D008780:Methyltransferases / Q000737:chemistry* / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D011487:Protein Conformation; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry* / Q000378:metabolism*; D016415:Sequence Alignment / Q000379:methods
D011994:Recombinant Proteins; D008780:Methyltransferases; C494510:GNMT protein, human; D050938:Glycine N-Methyltransferase; C494511:Gnmt protein, mouse; C494512:Gnmt protein, rat