C. Indiani et al., Effect of low temperature on soybean peroxidase: spectroscopic characterization of the quantum-mechanically admixed spin state, J INORG BIO, 79(1-4), 2000, pp. 269-274
A spectroscopic study of soybean peroxidase (SBP) has been carried out usin
g electronic absorption, resonance Raman (RR) and electron paramagnetic res
onance (EPR) spectroscopy in order to determine the effects of temperature
on the heme spin state. Upon lowering the temperature a transition from hig
h spin to low spin is induced in SEP resulting from conformational changes
in the heme cavity, including a contraction of the heme core, the reorienta
tion of the vinyl group in position 2 of the porphyrin macrocycle, and the
binding of the distal His to the Fe atom. Moreover, the combined analysis o
f the data derived from the different techniques at both room and low tempe
ratures demonstrates that at low temperature the quantum-mechanically admir
ed spin state (QS) of SEP has RR frequencies different from those observed
for the QS species at room temperature. (C) 2000 Elsevier Science Inc. AII
rights reserved.