A highly thermostable ferritin from the hyperthermophilic archaeal anaerobe Pyrococcus furiosus |
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Authors: | Jana Tatur Peter-Leon Hagedoorn Marieke L Overeijnder Wilfred R Hagen |
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Institution: | (1) Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands |
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Abstract: | A ferritin from the obligate anaerobe and hyperthermophilic archaeon Pyrococcus furiosus (optimal growth at 100°C) has been cloned and overproduced in Escherichia coli to one-fourth of total cell-free extract protein, and has been purified in one step to homogeneity. The ferritin (PfFtn) is structurally similar to known bacterial and eukaryal ferritins; it is a 24-mer of 20 kDa subunits, which add up to a total Mr 480 kDa. The protein belongs to the non-heme type of ferritins. The 24-mer contains approximately 17 Fe (as isolated), 2,700 Fe (fully loaded), or <1 Fe (apoprotein). Fe-loaded protein exhibits an EPR spectrum characteristic for superparamagnetic core formation. At 25°C Vmax=25 mole core Fe3+ formed per min per mg protein when measured at 315 nm, and the K0.5=5 mM Fe(II). At 0.3 mM Fe(II) activity increases 100-fold from 25 to 85°C. The wild-type ferritin is detected in P. furiosus grown on starch. PfFtn is extremely thermostable; its activity has a half-life of 48 h at 100°C and 85 min at 120°C. No apparent melting temperature was found up to 120°C. The extreme thermostability of PfFtn has potential value for biotechnological applications. |
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Keywords: | Ferritin Hyperthermophile P furiosus Thermostability Anaerobe |
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