| AUTHOR |
TITLE |
Broadwater, J. A.,
Achim, C.,
Munck, E.,
Fox, B. G. |
Mössbauer Studies of the Formation and Reactivity of a Quasi-Stable Peroxo Intermediate of Stearoyl-Acyl Carrier Protein Δ9-Desaturase
Biochemistry; 1999; 38(38); 12197-12204. |
Materials and Methods
Stopped-Flow Spectroscopy. Stopped-flow experiments were performed using an OLIS stopped-flow device and rapid-scanning monochromator (Bogart, GA). The ram syringes, mixer, and optical cell were maintained at the desired temperature by using a refrigerated water bath and a methanol/water mixture. Reactions were initiated by rapidly mixing equal volumes of 4e- 9D (200 µM holoprotein) and 18:0-ACP (400 µM). To maximize the formation of peroxo9D, the 18:0-ACP solution was equilibrated with 1 atm of O2 prior to mixing. Absorbance spectra were recorded either from 560 to 780 nm or from 310 to 440 nm at a sampling rate of 1000 scans/s. |
Langouet, S.,
Mican, A. N.,
Muller, M.,
Fink, S. P.,
Marnett, L. J.,
Muhle, S. A.,
Guengerich, F. P. |
Misincorporation of Nucleotides opposite Five-Membered Exocyclic Ring Guanine Derivatives by Escherichia coli Polymerases in Vitro and in Vivo: 1,N2-Ethenoguanine, 5,6,7,9-Tetrahydro-9-oxoimidazo[1,2-a]purine, and 5,6,7,9-Tetrahydro-7-hydroxy-9-oxoimidazo
Biochemistry; 1998; 37(15); 5184-5193. (Article) |
Experimental Procedures
Instrumental Analysis. UV spectra were recorded using a modified Cary 14/OLIS instrument operating at ambient temperature (On-Line Instrument Systems, Bogart, GA). |
Furge, L. L.,
Guengerich, F. P. |
Pre-Steady-State Kinetics of Nucleotide Insertion following 8-Oxo-7,8-dihydroguanine Base Pair Mismatches by Bacteriophage T7 DNA Polymerase exo-
Biochemistry; 1998; 37(10); 3567-3574. (Article) |
Experimental Procedures
Oligonucleotides. Concentrations of purified oligonucleotides were estimated by UV absorbance (260 nm) from spectra determined using a modified Cary-14/OLIS spectrophotometer (On-Line Instrument Systems, Bogart, GA). |
Guengerich, F. P.,
Johnson, W. W. |
Kinetics of Ferric Cytochrome P450 Reduction by NADPH-Cytochrome P450 Reductase: Rapid Reduction in the Absence of Substrate and Variations among Cytochrome P450 Systems
Biochemistry; 1997; 36(48); 14741-14750. (Article) |
Experimental Procedures
Spectroscopy. Absorbance spectra were recorded using modified Aminco DW2/OLIS and Cary 14/OLIS instruments (On-Line Instrument Systems, Bogart, GA). Second-derivative spectra were obtained using the manufacturer's software, with the application of the curve smoothing program. Analysis of second-derivative spectra involved the zero-baseline method. |
Furge, L. L.,
Guengerich, F. P. |
Analysis of Nucleotide Insertion and Extension at 8-Oxo-7,8-dihydroguanine by Replicative T7 Polymerase exo- and Human Immunodeficiency Virus-1 Reverse Transcriptase Using Steady-State and Pre-Steady-State Kinetics
Biochemistry; 1997; 36(21); 6475-6487. (Article) |
Experimental Procedures
Oligonucleotides. Concentrations of purified oligonucleotides were estimated by UV absorbance (260 nm) from spectra determined using a modified Cary-14/OLIS spectrophotometer (On-Line Instrument Systems, Bogart, GA). |
Ueng, Y.-F.,
Kuwabara, T.,
Chun, Y.-J.,
Guengerich, F. P. |
Cooperativity in Oxidations Catalyzed by Cytochrome P450 3A4
Biochemistry; 1997; 36(2); 370-381. (Article) |
Experimental Procedures
Spectroscopy. P450 and NADPH-P450 reductase spectra were recorded using an OLIS/Aminco DW2 instrument (On-Line Instrument Systems, Bogart, GA). |
Johnson, W. W.,
Harris, T. M.,
Guengerich, F. P. |
Kinetics and Mechanism of Hydrolysis of Aflatoxin B1 exo-8,9-Epoxide and Rearrangement of the Dihydrodiol
Journal of the American Chemical Society; 1996; 118(35); 8213-8220. (Article) |
Experimental Section
Spectroscopy. Absorbance spectra were recorded with a Cary 14/OLIS spectrophotometer (On-Line Instrument Systems, Bogart, GA). Absorbance spectra of AFB1 8,9-epoxide were measured in anhydrous (CH3)2CO and those of AFB1 diol in buffer at pH 3. |
Dong, M.-S.,
Bell, L. C.,
Guo, Z.,
Phillips, D. R.,
Blair, I. A.,
Guengerich, F. P. |
Identification of Retained N-Formylmethionine in Bacterial Recombinant Mammalian Cytochrome P450 Proteins with the N-Terminal Sequence MALLLAVFL...: Roles of Residues 3-5 in Retention and Membrane Topology
Biochemistry; 1996; 35(31); 10031-10040. (Article) |
Experimental Section
Spectroscopy and Other Procedures. P450 spectra were recorded using a modified Aminco DW2a/OLIS instrument (On-Line Instrument Systems, Bogart, GA). |
Lowe, L. G.,
Guengerich, F. P. |
Steady-State and Pre-Steady-State Kinetic Analysis of dNTP Insertion Opposite 8-Oxo-7,8-dihydroguanine by Escherichia coli Polymerases I exo- and II exo-
Biochemistry; 1996; 35(30); 9840-9849. (Article) |
Experimental Section
Oligonucleotide Synthesis.
Concentrations of purified oligonucleotides were estimated by UV absorbance at 260 nm on a modified Cary-14/OLIS spectrophotometer (On-Line Instrument Systems, Bogart, GA). |
Lin, S.-H.,
Faller, L. D. |
Estimation of the Distance Change between Cysteine-457 and the Nucleotide Binding Site When Sodium Pump Changes Conformation from E1 to E2 by Fluorescence Energy Transfer Measurements
Biochemistry; 1996; 35(25); 8419-8428. (Article) |
Methods
Stopped-Flow Measurements. The stopped-flow instrument consists of a Hi-Tech PQ/SF-53 sample handling unit integrated into an On-Line Instrument Systems spectrofluorometer (Faller et al., 1991; Smirnova & Faller, 1993b; Lin & Faller, 1993). All of the measurements were made at 15º C in 50 mM Tris-HCl buffer at pH 7.4 with the ionic strength (µ) adjusted to 250 mM with ChoCl. From 8 to 11 kinetic curves of 1000 points were stored and analyzed in each experiment at a single ion concentration. First-order rate constants and amplitudes were estimated by fitting the equation for a single exponential to the data by successive integration with the algorithm supplied by On-Line Instrument Systems. |
