title: Identification of a denitrase activity against calmodulin in activated macrophages using high-field liquid chromatography--FTICR mass spectrometry.
abstract: We have identified a denitrase activity in macrophages that is upregulated following macrophage activation, which is shown by mass spectrometry to recognize nitrotyrosines in the calcium signaling protein calmodulin (CaM). The denitrase activity converts nitrotyrosines to their native tyrosine structure without the formation of any aminotyrosine. Comparable extents of methionine sulfoxide reduction are also observed that are catalyzed by endogenous methionine sulfoxide reductases. Competing with repair processes, oxidized CaM is a substrate for a peptidase activity that results in the selective cleavage of the C-terminal lysine (i.e., Lys148) that is expected to diminish CaM function. Thus, competing repair and peptidase activities define the abundances and functionality of CaM in modulating cellular metabolism in response to oxidative stress, where the presence of the truncated CaM species provides a useful biomarker for the transient appearance of oxidized CaM.
authors: Biological Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA.
authors: Heather S
authors: HS
authors: Smallwood
authors: Natacha M
authors: NM
authors: Lourette
authors: Curt B
authors: CB
authors: Boschek
authors: Diana J
authors: DJ
authors: Bigelow
authors: Richard D
authors: RD
authors: Smith
authors: Ljiljana
authors: L
authors: Pasa-Tolić
authors: Thomas C
authors: TC
authors: Squier
mesh_terms: D000818:Animals; D002147:Calmodulin / Q000378:metabolism*; D002645:Chickens; D002853:Chromatography, Liquid / Q000379:methods*; D008239:Lysine / Q000378:metabolism; D008262:Macrophage Activation; D008264:Macrophages / Q000201:enzymology*; D013058:Mass Spectrometry / Q000379:methods*; D051379:Mice; D010084:Oxidation-Reduction; D020033:Protein Isoforms / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D002147:Calmodulin; D020033:Protein Isoforms; C002744:3-nitrotyrosine; D014443:Tyrosine; D008239:Lysine