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Yon, J. M.

doi:10.1016/s0300-9084(76)80238-6

Cited by 7 publications

(1 citation statement)

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“…The sulphides and selenides of titanium and zirconium have been calculated by an SC-OPW procedure by a Finnish group [51,52]. This implies that no muffin-tin approximation for the potential was involved.…”

Section: ~X~*(r-rp)v~(r-rq)xj(r-rp)dv (33)mentioning

confidence: 99%

Band structure of transition metal compounds

Calais

1977

Advances in Physics

162

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Section: ~X~*(r-rp)v~(r-rq)xj(r-rp)dv (33)mentioning

confidence: 99%

Band structure of transition metal compounds

Calais

1977

Advances in Physics

162

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Modification of Escherichia coli Thymidylate Synthase at Tyrosine-94 by 5-Imidazolylpropynyl-2‘-deoxyuridine 5‘-Monophosphate

et al. 2003

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Evidence is presented that 5-imidazolylpropynyl-2'-deoxyuridine 5'-monophosphate (IP-dUMP) is a mechanism-based, irreversible inactivator of Escherichia coli thymidylate synthase (TS), which covalently modifies Tyr94 at the active site of the enzyme. The inactivation of TS was time and concentration dependent and did not require the folate cofactor. Due to the rapidity of the inactivation process, accurate kinetic parameters could be determined only in the presence of saturating concentrations (1000K(M)) of the competing substrate, dUMP. Under these conditions, a K(I) of 0.36 +/- 0.09 microM and an inactivation rate constant (k(inact)) of 0.53 +/- 0.15 min(-1) were obtained from Kitz-Wilson plots. Electrospray ionization-mass spectrometry (ESI-MS) determined a 412 amu mass increase of TS after inhibition by IP-dUMP with no mass difference being detected for the TS mutants Tyr94Phe or Cys146Ala, thus indicating the importance of these residues for complex formation. The change in WT-TS mass was consistent with covalent modification by IP-dUMP, which was confirmed by proteolytic digestion of the modified protein followed by ESI-MS. By these means, a 43-residue trypsin peptide (residues 54-96), a 16-residue endoAspN peptide (residues 89-104), and an 8-residue endoAspN/endoLysC peptide (residues 89-96), each containing the IP-dUMP adduct, were observed. MS/MS analysis of the IP-dUMP-endoAspN peptide identified a modified 3-residue daughter ion, YGK (residues 94-96). A mechanistic scheme requiring the participation of Cys146 is proposed for the covalent modification of IP-dUMP by Tyr94, which, unlike an earlier proposal [Kalman, T. I., Nie, Z., and Kamat, A. (2001) Nucleosides Nucleotides Nucleic Acids 20, 869-871], does not require the release of imidazole for the activation of the inhibitor.

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Studies on the Interaction of NADPH with Rhodobacter sphaeroides Biotin Sulfoxide Reductase

Nelson¹,

Rajagopalan²

2004

Biochemistry

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Rhodobacter sphaeroides biotin sulfoxide reductase (BSOR) contains the bis(molybdopterin guanine dinucleotide)molybdenum cofactor and catalyzes the reduction of D-biotin-D-sulfoxide to biotin. This protein is the only member of the dimethyl sulfoxide reductase family of molybdopterin enzymes that utilizes NADPH as the direct electron donor to the catalytic Mo center. Kinetic studies using stopped-flow spectrophotometry indicate that BSOR reduction by NADPH (>1000 s(-1)) is faster than steady-state turnover (440 s(-1)) and has shown that BSOR reduction occurs in concert with NADPH oxidation with no indication of a Mo(V) intermediate species. Because no crystallographic structure is currently available for BSOR, a protein structure was modeled using the structures for R. sphaeroides dimethyl sulfoxide reductase, Rhodobacter capsulatus dimethyl sulfoxide reductase, and Shewanella massilia trimethylamine N-oxide reductase as the templates. A potential NADPH-binding site was identified and tested by site-directed mutagenesis of residues within the area. Mutation of Arg137 or Asp136 reduced the ability of NADPH to serve as the electron donor to BSOR, indicating that the NADPH-binding site in BSOR is located in the active-site funnel of the putative structure where it can directly reduce the Mo center. Along with kinetic and spectroscopic data, the location of this binding site supports a direct hydride transfer mechanism for NADPH reduction of BSOR.

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Cited by 7 publications

References 0 publications

Band structure of transition metal compounds

Band structure of transition metal compounds

Modification of Escherichia coli Thymidylate Synthase at Tyrosine-94 by 5-Imidazolylpropynyl-2‘-deoxyuridine 5‘-Monophosphate

Studies on the Interaction of NADPH with Rhodobacter sphaeroides Biotin Sulfoxide Reductase

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