Unambiguous Determination of Protein Arginine Ionization States in Solution by NMR Spectroscopy. (29th November 2016) - Yoshimura, Yuichi
Abstract: Because arginine residues in proteins are expected to be in their protonated form almost without exception, reports demonstrating that a protein arginine residue is charge‐neutral are rare and potentially controversial. Herein, we present a 13 C‐detected NMR experiment for probing individual arginine residues in proteins notwithstanding the presence of chemical and conformational exchange effects. In the experiment, the 15 N η and 15 N ϵ chemical shifts of an arginine head group are correlated with that of the directly attached 13 C ζ . In the resulting spectrum, the number of protons in the arginine head group can be obtained directly from the 15 N– 1 H scalar coupling splitting pattern. We applied this method to unambiguously determine the ionization state of the R52 side chain in the photoactive yellow protein from Halorhodospira halophila . Although only three H η atoms were previously identified by neutron crystallography, we show that R52 is predominantly protonated in solution. Abstract : Protonenzählen : Mit einem NMR‐Experiment gelingt das direkte Bestimmen der Zahl an Protonen in der Arginin‐Kopfgruppe. Auf diese Art lässt sich der Ladungszustand von Arginin‐Seitenketten zweifelsfrei ermitteln, wie anhand des Argininrests im aktiven Zentrum des photoaktiven gelben Proteins gezeigt wird.