PMID- 21107981
OWN - NLM
STAT- MEDLINE
DCOM- 20110614
LR  - 20211020
IS  - 1432-1017 (Electronic)
IS  - 0175-7571 (Linking)
VI  - 40
IP  - 3
DP  - 2011 Mar
TI  - Solvent effect on librational dynamics of spin-labelled haemoglobin by ED- and 
      CW-EPR.
PG  - 273-9
LID - 10.1007/s00249-010-0644-5 [doi]
AB  - Two-pulse, echo-detected electron paramagnetic resonance (ED-EPR) spectra and 
      continuous-wave EPR (CW-EPR) spectra were used to investigate the solvent effect 
      on the librational motion of human haemoglobin spin-labelled on cysteine beta93 with 
      the nitroxide derivative of maleimide, 6-MSL. Protein samples fully hydrated in 
      phosphate buffer solution (PBS), in a 60% v/v glycerol/water mixture and in the 
      lyophilized form were measured at cryogenic temperature in the frozen state. The 
      protein librational motion was characterized by the amplitude-correlation time 
      product, <alpha(2)>tau(c), deduced from the ED-EPR spectra. The librational amplitude, 
      <alpha(2)>tau(c), was determined independently, from the motionally averaged hyperfine 
      splitting in the CW-EPR spectra, and the librational correlation time, tau(c), was 
      derived from the combination of the pulsed and conventional EPR data. Rapid 
      librational motion of small amplitude was detected in all samples. In each case, 
      the librational dynamics was restricted up to 180 K, beyond which it increased 
      steeply for the hydrated protein in PBS and in the presence of glycerol. In 
      contrast, in the dehydrated protein, the librational dynamics was hindered and 
      less dependent on temperature up to ~240 K. In all samples, <alpha(2)> deviated from 
      small values only for T > 200 K, where a rapid increase of <alpha(2)> was evident for 
      the hydrated samples, whereas limited temperature variation was shown in the 
      lyophilized samples. The librational correlation time was in the sub-nanosecond 
      regime and weakly dependent on temperature. The results evidence that solvent 
      favours protein dynamics.
FAU - Scarpelli, Francesco
AU  - Scarpelli F
AD  - Dipartimento di Fisica, Laboratorio di Biofisica Molecolare and UdR CNISM, 
      Universita della Calabria, 87036 Arcavacata di Rende, CS, Italy.
FAU - Bartucci, Rosa
AU  - Bartucci R
FAU - Sportelli, Luigi
AU  - Sportelli L
FAU - Guzzi, Rita
AU  - Guzzi R
LA  - eng
PT  - Journal Article
DEP - 20101125
PL  - Germany
TA  - Eur Biophys J
JT  - European biophysics journal : EBJ
JID - 8409413
RN  - 0 (Hemoglobins)
RN  - 0 (Solvents)
RN  - 0 (Spin Labels)
SB  - IM
MH  - Electron Spin Resonance Spectroscopy/*methods
MH  - Hemoglobins/*chemistry
MH  - Humans
MH  - *Models, Chemical
MH  - Motion
MH  - Solvents/*chemistry
MH  - Spin Labels/*chemical synthesis
MH  - Temperature
EDAT- 2010/11/26 06:00
MHDA- 2011/06/15 06:00
CRDT- 2010/11/26 06:00
PHST- 2010/07/26 00:00 [received]
PHST- 2010/11/10 00:00 [accepted]
PHST- 2010/10/08 00:00 [revised]
PHST- 2010/11/26 06:00 [entrez]
PHST- 2010/11/26 06:00 [pubmed]
PHST- 2011/06/15 06:00 [medline]
AID - 10.1007/s00249-010-0644-5 [doi]
PST - ppublish
SO  - Eur Biophys J. 2011 Mar;40(3):273-9. doi: 10.1007/s00249-010-0644-5. Epub 2010 
      Nov 25.