Amy M Grunden

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Proline dipeptidase (prolidase) was purified from cell extracts of the proteolytic, hyperthermophilic archaeon Pyrococcus furiosus by multistep chromatography. The enzyme is a homodimer (39.4 kDa per subunit) and as purified contains one cobalt atom per subunit. Its catalytic activity also required the addition of Co2+ ions (Kd, 0.24 mM), indicating that(More)
The modABC gene products constitute the molybdate-specific transport system in Escherichia coli. Another operon coding for two proteins which diverges from the modABCD operon has been identified. The first gene of this operon codes for a 262-amino-acid protein, designated ModE (28 kDa), and the second genes codes for a 490-amino-acid protein. ModF (54 kDa).(More)
The structure of prolidase from the hyperthermophilic archaeon Pyrococcus furiosus (Pfprol) has been solved and refined at 2.0 A resolution. This is the first structure of a prolidase, i.e., a peptidase specific for dipeptides having proline as the second residue. The asymmetric unit of the crystals contains a homodimer of the enzyme. Each of the two(More)
There are classes of microbial enzymes that have the ability to degrade harmful organophosphorus (OP) compounds that are present in some pesticides and nerve agents. To date, the most studied and potentially important OP-degrading enzymes are organophosphorus hydrolase (OPH) and organophosphorus acid anhydrolase (OPAA), which have both been characterized(More)
The hyperthermophilic archaeon Pyrococcus furiosus grows optimally at 100 degrees C by the fermentation of peptides and carbohydrates. Growth of the organism was examined in media containing either maltose, peptides (hydrolyzed casein), or both as the carbon source(s), each with and without elemental sulfur (S(0)). Growth rates were highest on media(More)
Prolidases are dipeptidases specific for cleavage of Xaa-Pro dipeptides. Pyrococcus furiosus prolidase is a homodimer having one Co-bound dinuclear metal cluster per monomer with one tightly bound Co(II) site and the other loosely bound (Kd 0.24 mM). To identify which Co site is tight-binding and which is loose-binding, site-directed mutagenesis was used to(More)
Combined gasification and fermentation technologies can potentially produce biofuels from renewable biomass. Gasification generates synthesis gas consisting primarily of CO, CO(2), H(2), N(2), with smaller amounts of CH(4), NO(x), O(2), C(2) compounds, ash and tars. Several anaerobic bacteria species can ferment bottled mixtures of pure synthesis gas(More)
Escherichia coli growing under anaerobic conditions produces several molybdoenzymes, such as formate hydrogenlyase (formate to H2 and CO2; hyc and fdhF genes) and nitrate reductase (narGHJI genes). Synthesis of these molybdoenzymes, even in the presence of the cognate transcriptional activators and effectors, requires molybdate in the medium. Besides the(More)
Molybdate is transported in bacteria by a high-affinity transport system composed of a periplasmic binding protein, an integral membrane protein, and an energizer protein. These three proteins are coded by modA, modB, and modC genes, respectively. The ModA, ModB, and ModC proteins from various organisms (Escherichia coli, Haemophilus influenzae, Azotobacter(More)