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Zinc and cadmium complexation of L‐methionine: An infrared multiple photon dissociation spectroscopy and theoretical study
Author(s) -
Boles Georgia C.,
Stevenson Brandon C.,
Hightower Randy L.,
Berden Giel,
Oomens Jos,
Armentrout P. B.
Publication year - 2021
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.4580
Subject(s) - chemistry , infrared multiphoton dissociation , conformational isomerism , dissociation (chemistry) , deprotonation , infrared spectroscopy , zinc , metal , sulfur , acetonitrile , spectroscopy , carboxylate , photochemistry , stereochemistry , inorganic chemistry , crystallography , molecule , organic chemistry , ion , physics , quantum mechanics
Methionine (Met) cationized with Zn 2+ , forming Zn (Met–H) + (ACN) where ACN = acetonitrile, Zn (Met–H) + , and ZnCl + (Met), as well as Cd 2+ , forming CdCl + (Met), were examined by infrared multiple photon dissociation (IRMPD) action spectroscopy using light generated from the FELIX free electron laser. A series of low‐energy conformers for each complex was found using quantum‐chemical calculations in order to identify the structures formed experimentally. For all four complexes, spectral comparison indicated that the main binding motif observed is a charge solvated, tridentate structure where the metal center binds to the backbone amino group nitrogen, backbone carbonyl oxygen (where the carboxylic acid is deprotonated in two of the Zn 2+ complexes), and side‐chain sulfur. For all species, the predicted ground structures reproduce the experimental spectra well, although low‐lying conformers characterized by similar binding motifs may also contribute in each system. The current work provides valuable information regarding the binding interaction between Met and biologically relevant metals. Further, the comparison between the current work and previous analyses involving alkali metal cationized Met as well as cysteine (the other sulfur containing amino acid) cationized with Zn 2+ and Cd 2+ allows for the elucidation of important metal dependent trends associated with physiologically important metal–sulfur binding.