Tion (Manassas, VA). 5′-Deoxyadenosine (5′-dA), sodium sulfide (nonahydrate), sodium dithionite (DT), -mercaptoethanol, L-tryptophan, L-(+)-arabinose, and ferric chloride were bought from Sigma ldrich Chemical compounds (St. Louis, MO). N-(2hydroxyethyl)piperazine-N’-(2-ethanesulfonic acid) (HEPES) was purchased from Fisher Scientific (Pittsburgh, PA), and imidazole was bought from J. T. Baker Chemical Co (Phillipsburg, NJ). Potassium chloride and glycerol have been bought from EMD Chemicals (Gibbstown, NJ), though dithiothreitol (DTT) was purchased from Gold Biotechnology (St. Louis, MO). Coomassie blue dye-binding reagent for protein concentration determination was purchased from Pierce (Rockford, IL), as was the bovine serum albumin (BSA) standard (two mg/mL). Talon metal affinity resin was purchased from Clontech (Mountain View, CA). Sephadex G-25 resin and NICK and NAP prepoured gel filtration columns were bought from GE Biosciences (Piscataway, NJ). Fmoc-Thr(tBu)-OH (99 ), Fmoc-allo-NIH-PA Author ManuscriptBiochemistry. Author manuscript; available in PMC 2014 April 30.Grove et al.PageThr(tBu)-OH (99 ), and Fmoc-Se-4-methoxybenzyl selenocysteine (99 ) were bought from Chem-Impex International. All other chemical compounds have been with the highest grade accessible.NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptS-Adenosyl-L-methionine (SAM) was synthesized enzymatically and purified as described previously (32). Flavodoxin (Flv) and flavodoxin reductase (Flx) had been purified from E. coli BL21(DE3) containing plasmids pTYB1-Flv and pTYB1-Flx as described previously (33, 34). Fmoc-formylglycine (dimethylacetal) was kindly offered by Professor Carolyn Bertozzi and Dr. Jason Rush (UC Berkeley). DNA sequencing was carried out at the Pennsylvania State University Nucleic Acid Facility. Analyses for iron and sulfide had been performed by the procedures of Beinert (35-37). SPEX CertiPrep (Metuchen, NJ) Cl itas PPT single element Fe (1000 mg/L in 2 HNO3) was utilised to prepare iron standards for quantitative iron analysis. Protein concentration was measured by the procedure of Bradford applying bovine serum albumin (Fraction V) as a typical (38). Spectroscopic Techniques UV-visible spectra were recorded on a Cary 50 spectrometer (Dopamine Receptor Modulator Compound Varian, Walnut Creek, CA) employing the related WinUV software program package for operating the instrument and manipulating the information. M sbauer spectra had been recorded on a spectrometer from Net Research (Edina, MN), which was equipped with an SVT-400 cryostat from Janis Research Co (Wilmington, MA). Spectra had been collected in continuous acceleration mode in transmission geometry. Isomer shifts are quoted relative for the centroid of -Fe at room temperature. Spectra have been analyzed using the plan WMOSS from Web Study. 57Fe (97-98 ) metal for M sbauer spectroscopy was bought from iNOS Inhibitor Purity & Documentation Isoflex USA (San Francisco, CA). For preparation of a 57FeSO4 option, the strong was dissolved with heating in an anaerobic answer of 2 N H2SO4 (1.5 mol of H2SO4 per mole of 57Fe). The 57Fe answer was utilized as is for supplementation in E. coli culture media, or was titrated to pH 6.five with an anaerobic solution of saturated sodium bicarbonate for in vitro reconstitution. X-band ( 9.five GHz) electron paramagnetic resonance (EPR) spectroscopy was conducted on a Bruker ESP 300 spectrometer equipped with an Oxford Instruments Model ESP 900 continuous flow cryostat. EPR parameters for many samples are provided in the suitable figure legends. Cloning.