title: A complex of methylthioadenosine/S-adenosylhomocysteine nucleosidase, transition state analogue, and nucleophilic water identified by mass spectrometry.
abstract: An enzyme-stabilized nucleophilic water molecule has been implicated at the transition state of  Escherichia coli  methylthioadenosine nucleosidase (EcMTAN) by transition state analysis and crystallography. We analyzed the EcMTAN mass in complex with a femtomolar transition state analogue to determine whether the inhibitor and nucleophilic water could be detected in the gas phase. EcMTAN-inhibitor and EcMTAN-inhibitor-nucleophilic water complexes were identified by high-resolution mass spectrometry under nondenaturing conditions. The enzyme-inhibitor-water complex is sufficiently stable to exist in the gas phase.
authors.affiliation: Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA.
authors.forename: Shanzhi
authors.initials: S
authors.lastname: Wang
authors.forename: Jihyeon
authors.initials: J
authors.lastname: Lim
authors.forename: Keisha
authors.initials: K
authors.lastname: Thomas
authors.forename: Funing
authors.initials: F
authors.lastname: Yan
authors.forename: Ruth H
authors.initials: RH
authors.lastname: Angeletti
authors.forename: Vern L
authors.initials: VL
authors.lastname: Schramm
mesh_terms: D003839:Deoxyadenosines / Q000737:chemistry / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D013058:Mass Spectrometry; D008958:Models, Molecular; D009699:N-Glycosyl Hydrolases / Q000378:metabolism*; D013379:Substrate Specificity; D013872:Thionucleosides / Q000737:chemistry / Q000378:metabolism*
chemical_list: D003839:Deoxyadenosines; D013872:Thionucleosides; C008500:5'-methylthioadenosine; D009699:N-Glycosyl Hydrolases; C019606:adenosylhomocysteine nucleosidase