title: Locating Pb2+ and Zn2+ in zinc finger-like peptides using mass spectrometry.
abstract: The binding preferences of Pb(2+)and Zn(2+) in doubly charged complexes with zinc finger-like 12-residue peptides (Pep), [Mn(Pep-2(n-1)H)](2+) have been explored using tandem mass spectrometry. The peptides were synthesized strategically by blocking the N-terminus with an acetyl group and with four cysteine and/or histidine residues in positions 2, 5, 8, and 11, arranged in different motifs: CCHH, CHCH, and CCCC. The MS(2) spectra of the Pb(2+) and Zn(2+) complexes show multiple losses of water and a single methane loss and these provide a sensitive method for locating the metal dication and so elucidating its coordination. The elimination of a methane molecule indicated the position of the metal at the Cys2 residue. Whereas lead was observed to preferentially bind to cysteine residues, zinc was found to primarily bind to histidine residues and secondarily to cysteine residues. Preferential binding of lead to cysteine is preserved in the complexes with more than one Pb(2+). Key to the mechanism of the loss of water and methane is the metal dication withdrawing electrons from the proximal amidic nitrogen. This acidic nitrogen loses its hydrogen to an amidic oxygen situated four atoms away leading to formation of a five-member ring and the elimination of water.
authors.affiliation: Department of Chemistry, Centre for Research in Mass Spectrometry, York University, Toronto, Ontario, M3J 1P3, Canada.
authors.forename: Laura
authors.initials: L
authors.lastname: Banu
authors.forename: Voislav
authors.initials: V
authors.lastname: Blagojevic
authors.forename: Diethard K
authors.initials: DK
authors.lastname: Bohme
mesh_terms: D003545:Cysteine / Q000737:chemistry / Q000378:metabolism; D006639:Histidine / Q000737:chemistry / Q000378:metabolism; D007854:Lead / Q000737:chemistry* / Q000378:metabolism; D009842:Oligopeptides / Q000737:chemistry* / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry; D015032:Zinc / Q000737:chemistry* / Q000378:metabolism; D016335:Zinc Fingers
chemical_list: D009842:Oligopeptides; D007854:Lead; D006639:Histidine; D015032:Zinc; D003545:Cysteine
references.citation: J Am Chem Soc. 2005 Jul 6;127(26):9495-505
references.pmid: 15984876
references.citation: Inorg Chem. 2004 Sep 20;43(19):5798-800
references.pmid: 15360227
references.citation: Biopolymers. 2010 Jun;93(6):497-508
references.pmid: 20091672
references.citation: Science. 1991 May 10;252(5007):809-17
references.pmid: 2028256
references.citation: Rapid Commun Mass Spectrom. 2010 Nov 30;24(22):3279-89
references.pmid: 20973002
references.citation: Rapid Commun Mass Spectrom. 2009 Jul;23(13):2045-52
references.pmid: 19504478
references.citation: Nature. 2001 Feb 15;409(6822):860-921
references.pmid: 11237011
references.citation: J Mol Graph Model. 2006 Mar;24(5):404-11
references.pmid: 16298534
references.citation: J Nutr. 1976 May;106(5):689-96
references.pmid: 1262976
references.citation: J Mass Spectrom. 2008 Jun;43(6):773-81
references.pmid: 18205239
references.citation: Anal Chem. 1999 Jul 1;71(13):2364-72
references.pmid: 10405604
references.citation: Annu Rev Biochem. 1972;41(10):91-128
references.pmid: 4570963
references.citation: Annu Rev Biophys Biomol Struct. 2000;29:183-212
references.pmid: 10940247
references.citation: J Phys Chem A. 2007 Nov 15;111(45):11562-71
references.pmid: 17949063
references.citation: J Am Soc Mass Spectrom. 1994 Nov;5(11):959-65
references.pmid: 24226385
references.citation: Curr Opin Chem Biol. 2001 Apr;5(2):223-7
references.pmid: 11282351
references.citation: J Am Soc Mass Spectrom. 2004 Jul;15(7):1039-54
references.pmid: 15234363
references.citation: J Phys Chem A. 2011 Jun 23;115(24):6683-7
references.pmid: 21595464
references.citation: Nat Struct Biol. 1994 Jun;1(6):345-9
references.pmid: 7664042
references.citation: Inorg Chem. 2006 Aug 21;45(17):6574-6
references.pmid: 16903704
references.citation: J Mass Spectrom. 2000 Feb;35(2):265-76
references.pmid: 10679990
references.citation: Rapid Commun Mass Spectrom. 2006;20(4):618-28
references.pmid: 16444685
references.citation: Anal Chem. 2002 May 1;74(9):2072-82
references.pmid: 12033309