Research Article

Model-free analysis of a thermophilic Fe7S8 protein compared with a mesophilic Fe4S4 protein

  1. Ivano Bertini1,2,*,
  2. Claudio Luchinat2,3,
  3. Yohei Niikura1,2,
  4. Chiara Presenti1,2

Article first published online: 28 JUL 2000

DOI: 10.1002/1097-0134(20001001)41:1<75::AID-PROT100>3.0.CO;2-2

Issue

Proteins: Structure, Function, and Bioinformatics

Proteins: Structure, Function, and Bioinformatics

Volume 41, Issue 1, pages 75–85, 1 October 2000

Additional Information

How to Cite

Bertini, I., Luchinat, C., Niikura, Y. and Presenti, C. (2000), Model-free analysis of a thermophilic Fe7S8 protein compared with a mesophilic Fe4S4 protein. Proteins: Structure, Function, and Bioinformatics, 41: 75–85. doi: 10.1002/1097-0134(20001001)41:1<75::AID-PROT100>3.0.CO;2-2

Author Information

  1. 1

    Department of Chemistry, University of Florence, Florence, Italy

  2. 2

    Centro di Risonanze Magnetiche, University of Florence, Sesto Fiorentino, Italy

  3. 3

    Department of Soil Science and Plant Nutrition, University of Florence, Florence, Italy

*Department of Chemistry and Centro di Risonanze Magnetiche, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Italy

Publication History

  1. Issue published online: 28 JUL 2000
  2. Article first published online: 28 JUL 2000
  3. Manuscript Accepted: 11 MAY 2000
  4. Manuscript Received: 2 DEC 1999

Funded by

  • MURST ex 40%, Italy
  • CNR (Progetto: Struttura e dinamica di metalloproteine mediante studi spettroscopici), Italy. Grant Number: NMR 9801789.03

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Keywords:

  • internal mobility;
  • temperature;
  • NMR;
  • paramagnetism;
  • 15N relaxation;
  • order parameter;
  • correlation time;
  • iron-sulfur protein

Abstract

15N T1, T2 and 1H-15N NOE were measured for the thermophilic Fe7S8 protein from Bacillus schlegelii and for the Fe4S4 HiPIP protein from Chromatium vinosum, which is a mesophilic protein. The investigation was performed at 276, 300, and 330 K at 11.7 T for the former, whereas only the 298 K data at 14.1 T for the latter were acquired. The data were analyzed with the model-free protocol after correcting the measured parameters for the effect of paramagnetism, because both proteins are paramagnetic. Both thermophilic and mesophilic proteins are quite rigid, with an average value of the generalized order parameter S2at room temperature of 0.92 and 0.94 for Fe7S8 and Fe4S4 proteins, respectively. The analyzed nitrogens for the Fe7S8 protein showed a significant decrease in S2with increasing temperature, and at the highest temperature >70% of the residues had an internal correlation time. This research shows that subnanosecond rigidity is not related to thermostability and provides an estimate of the effect of increasing temperature on this time scale. Proteins 2000;41:75–85. © 2000 Wiley-Liss, Inc.

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