geoscience.net logo
+ Resolve Article
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter

+ Translate
+ Subscribe to Site Feed
GeoScience Most Shared ContentMost Shared Content

High-frequency (140-GHz) time domain EPR and ENDOR spectroscopy: the tyrosyl radical-diiron cofactor in ribonucleotide reductase from yeast


, : High-frequency (140-GHz) time domain EPR and ENDOR spectroscopy: the tyrosyl radical-diiron cofactor in ribonucleotide reductase from yeast. Journal of the American Chemical Society 123(15): 3569-3576

High-frequency pulsed EPR and ENDOR have been employed to characterize the tyrosyl radical (Y*)-diiron cofactor in the Y2-containing R2 subunit of ribonucleotide reductase (RNR) from yeast. The present work represents the first use of 140-GHz time domain EPR and ENDOR to examine this system and demonstrates the capabilities of the method to elucidate the electronic structure and the chemical environment of protein radicals. Low-temperature spin-echo-detected EPR spectra of yeast Y* reveal an EPR line shape typical of a tyrosyl radical; however, when compared with the EPR spectra of Y* from E. coli RNR, a substantial upfield shift of the g(1)-value is observed. The origin of the shift in g(1) was investigated by 140-GHz (1)H and (2)H pulsed ENDOR experiments of the Y2-containing subunit in protonated and D(2)O-exchanged buffer. (2)H ENDOR spectra and simulations provide unambiguous evidence for one strongly coupled (2)H arising from a bond between the radical and an exchangeable proton of an adjacent residue or a water molecule. Orientation-selective 140-GHz ENDOR spectra indicate the direction of the hydrogen bond with respect to the molecular symmetry axes and the bond length (1.81 A). Finally, we have performed saturation recovery experiments and observed enhanced spin lattice relaxation rates of the Y* above 10 K. At temperatures higher than 20 K, the relaxation rates are isotropic across the EPR line, a phenomenon that we attribute to isotropic exchange interaction between Y* and the first excited paramagnetic state of the diiron cluster adjacent to it. From the activation energy of the rates, we determine the exchange interaction between the two irons of the cluster, J(exc) = -85 cm(-)(1). The relaxation mechanism and the presence of the hydrogen bond are discussed in terms of the differences in the structure of the Y*-diiron cofactor in yeast Y2 and other class I R2s.

US$29.90

PMID: 11472128


Other references

Henry, B.Michael.; Sanna, S.; Graves, M.J.; Vikse, J.; Sanna, B.; Tomaszewska, I.M.; Tubbs, R.Shane.; Walocha, J.A.; Tomaszewski, K.A., 2017: The Non-Recurrent Laryngeal Nerve: a meta-analysis and clinical considerations. The Non-Recurrent Laryngeal Nerve (NRLN) is a rare embryologically-derived variant of the Recurrent Laryngeal Nerve (RLN). The presence of an NRLN significantly increases the risk of iatrogenic injury and operative complications. Our aim was to pr...

Poulias, G.E.; Thrower, W.B., 1965: The Use Of Aortic Homograft As Esophageal Substitute. American Surgeon 31: 33-38

Miller G.G.; Creighton M.O.; Mousa G.Y.; Trevithick J.R., 1976: Growth and differentiation of new born rat lens epithelial cells in vitro. Canadian Federation of Biological Societies Proceedings 19: 92

Karube, Haruki., 1999: A new species of the genus Petaliaeschna Odonata, Aeschnidae from northern Vietnam. Gekkan-Mushi. April; 338: 6-7

Melo, A.C. de; Cota, B.B.; Oliveira, A.B. de; Braga, F.C., 2001: HPLC quantitation of kaurane diterpenes in Xylopia species. Xylopia frutescens is a tree native to the Brazilian Amazon whose seeds are rich in kaurenoic acid, a diterpene that showed in vitro activity against Trypanosoma cruzi. Aiming to find out alternative sources for kaurenoic acid, the content of some...

Bush, C.K., 1959: Clinical and pathological laboratories. Mental Hospitals 10: 32-32

Moon, T.Y.; Yoon, I.B., 1993: The list of orthoptera deposited in the Korean Entomological Institute, I. Deracanthidae and Tettigoniidae (Tettigonoidea). The orthopteran materials accumulated in Korean Entomological Institute (KEI) were examined. As a beginning part of the work, the Tettigonoidea composed of Deracanthidae and Tettigoniidae were put into systematic order and databased with informati...

Lang, S.; Mitak, M., 1989: Two steps forward--and one back?. In Croatia, as in Yugoslavia as a whole, the immense economic progress achieved since the Second World War has been accompanied by a marked decline in the prevalence of infectious and parasitic diseases. On the other hand there has been an upsurge...

Hutchison, B., 2009: Healthcare policy four years on. Healthcare Policy 4(3): 10-14

Bhoria, U.; Das, A.; Singh, G.; Suman, K., 1994: Multiple gall bladder adenomas. Indian Journal of Pathology & Microbiology 37 Suppl: S19-S20