scholarly journals Conformational Differences between the Methoxy Groups of QA and QB Site Ubisemiquinones in Bacterial Reaction Centers: A Key Role for Methoxy Group Orientation in Modulating Ubiquinone Redox Potential

Biochemistry ◽  
2013 ◽  
Vol 52 (27) ◽  
pp. 4648-4655 ◽  
Author(s):  
Alexander T. Taguchi ◽  
Patrick J. O’Malley ◽  
Colin A. Wraight ◽  
Sergei A. Dikanov
Keyword(s):  
Redox Potential ◽  
Methoxy Group ◽  
Reaction Centers ◽  
Group Orientation ◽  
Bacterial Reaction Centers ◽  
Methoxy Groups

Influence of Asn/His L166 on the Hydrogen-Bonding Pattern and Redox Potential of the Primary Donor of Purple Bacterial Reaction Centers†

Biochemistry ◽  
1997 ◽  
Vol 36 (10) ◽  
pp. 3027-3036 ◽  
Author(s):  
Anabella Ivancich ◽  
Tony A. Mattioli ◽  
Katie Artz ◽  
Shaojie Wang ◽  
James P. Allen ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Redox Potential ◽  
Reaction Centers ◽  
Hydrogen Bonding Pattern ◽  
Bacterial Reaction Centers ◽  
Primary Donor

Proximity and conformation effects in 29Si and 13C NMR spectra of di-ortho substituted trimethylsiloxybenzenes

1990 ◽  
Vol 55 (8) ◽  
pp. 2027-2032 ◽  
Author(s):  
Jan Schraml ◽  
Robert Brežný ◽  
Jan Čermák
Keyword(s):  
Benzene Ring ◽  
13C Nmr ◽  
Proximity Effect ◽  
Nmr Spectra ◽  
Methoxy Group ◽  
Chemical Shifts ◽  
Proximity Effects ◽  
13C Nmr Spectra ◽  
Methoxy Groups ◽  
C Nmr

29Si and 13C NMR spectra of five 4-substituted 2,6-dimethoxytrimethylsiloxybenzenes were studied with the aim to elucidate the nature of the deshielding proximity effects observed in the spectra of ortho substituted trimethylsiloxybenzenes. The sensitivity of 29Si chemical shifts to para substitution is in the studied compounds essentially the same as in mono ortho methoxytrimethylsiloxybenzenes. The deshielding proximity effect of the ìsecondî methoxy group is somewhat smaller than that of the ìfirstî group. The present results indicate that the two methoxy groups assume coplanar conformations with the benzene ring and are turned away from the trimethylsiloxy group which is not in the benzene plane. It is argued that in mono ortho methoxytrimethylsiloxybenzenes the two substituent groups adopt the same conformations as in the compounds studied here.

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