TY - JOUR
T1 - Low-temperature femtosecond-resolution transient absorption spectroscopy of large-scale symmetry mutants of bacterial reaction centers
AU - Lin, Su
AU - Xiao, Weizhong
AU - Eastman, J. Elizabeth
AU - Taguchi, Aileen K W
AU - Woodbury, Neal
PY - 1996/3/12
Y1 - 1996/3/12
N2 - Reaction centers isolated from three large-scale symmetry mutants, sym0, sym2-1, and sym5-2 described in the previous article of this issue [Taguchi, A. K. W., Eastman, J. E., Gallo, D. M., Jr., Sheagley, E., Xiao, W., and Woodbury, N. W. (1996) Biochemistry 35, 3175-3186] have been investigated by low-temperature ground state and femtosecond-resolution transient absorption spectroscopy. All three of these large-scale symmetry mutants undergo electron transfer at 20 K. The mutants sym0 and sym5-2 have yields and dominant rates of charge separation comparable to wild type. However, the sym2-1 mutant shows a roughly 35% quantum yield at this temperature, and the major kinetic component of the initial electron transfer is slower than wild type by nearly a factor of 100. The sym0 mutant showed substantial changes in the monomer bacteriochlorophyll ground state and transient spectra, and both sym0 and sym2-1 showed changes in the bacteriopheophytin ground state and transient spectra. In particular, sym2-1 shows a small absorbance decrease in the region of the Q(x) band of the B side bacteriopheophytin which could be attributed to 10%-20% electron transfer along the B pathway.
AB - Reaction centers isolated from three large-scale symmetry mutants, sym0, sym2-1, and sym5-2 described in the previous article of this issue [Taguchi, A. K. W., Eastman, J. E., Gallo, D. M., Jr., Sheagley, E., Xiao, W., and Woodbury, N. W. (1996) Biochemistry 35, 3175-3186] have been investigated by low-temperature ground state and femtosecond-resolution transient absorption spectroscopy. All three of these large-scale symmetry mutants undergo electron transfer at 20 K. The mutants sym0 and sym5-2 have yields and dominant rates of charge separation comparable to wild type. However, the sym2-1 mutant shows a roughly 35% quantum yield at this temperature, and the major kinetic component of the initial electron transfer is slower than wild type by nearly a factor of 100. The sym0 mutant showed substantial changes in the monomer bacteriochlorophyll ground state and transient spectra, and both sym0 and sym2-1 showed changes in the bacteriopheophytin ground state and transient spectra. In particular, sym2-1 shows a small absorbance decrease in the region of the Q(x) band of the B side bacteriopheophytin which could be attributed to 10%-20% electron transfer along the B pathway.
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U2 - 10.1021/bi952196z
DO - 10.1021/bi952196z
M3 - Article
C2 - 8605153
AN - SCOPUS:0029988202
SN - 0006-2960
VL - 35
SP - 3187
EP - 3196
JO - Biochemistry
JF - Biochemistry
IS - 10
ER -