title: NMR spectra of exchangeable protons of pyridoxal phosphate-dependent enzymes.
abstract: We have recorded 1H NMR spectra in H2O for exchangeable protons of four pyridoxal phosphate-dependent enzymes: D-serine dehydratase, aspartate aminotransferase, tryptophan: indole-lyase and glutamate decarboxylase. The molecular masses range from 48-250 kDa. In every case there are downfield peaks which are lost when the apoenzyme is formed. In most cases some peaks shift in response to interactions with substrates and inhibitors and with changes in pH. We associate one downfield resonance with the proton on the ring nitrogen of the coenzyme and others with imidazole groups that interact with coenzyme or substrates. The chemical shift for the coenzyme-bound proton differs for free enzyme, substrate Schiff base or quinonoid forms.
authors.affiliation: Department of Biochemistry and Biophysics, Iowa State University, Ames 50011.
authors.forename: C M
authors.initials: CM
authors.lastname: Metzler
authors.forename: D E
authors.initials: DE
authors.lastname: Metzler
authors.forename: A
authors.initials: A
authors.lastname: Kintanar
authors.forename: R D
authors.initials: RD
authors.lastname: Scott
authors.forename: M
authors.initials: M
authors.lastname: Marceau
mesh_terms: D000818:Animals; D001051:Apoenzymes / Q000737:chemistry / Q000378:metabolism; D001219:Aspartate Aminotransferases / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D004926:Escherichia coli / Q000201:enzymology; D005968:Glutamate Decarboxylase / Q000737:chemistry / Q000378:metabolism*; D006859:Hydrogen; D012695:L-Serine Dehydratase / Q000737:chemistry / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008968:Molecular Conformation; D009206:Myocardium / Q000201:enzymology; D011487:Protein Conformation; D011732:Pyridoxal Phosphate / Q000378:metabolism*; D013552:Swine; D014368:Tryptophanase / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001051:Apoenzymes; D011732:Pyridoxal Phosphate; D006859:Hydrogen; D001219:Aspartate Aminotransferases; D005968:Glutamate Decarboxylase; D014368:Tryptophanase; D012695:L-Serine Dehydratase