Resonance Raman and Fourier Transform Infrared Detection of Azide Binding to the Binuclear Center of Cytochrome bo₃ Oxidase from Escherichia coli

Abstract

Resonance Raman and FTIR spectra are reported for the oxidized azide-bound derivative of the quinol cytochrome bo 3 oxidase from Escherichia coli. The resonance Raman spectra display three isotope-dependent vibrational modes at 419, 2040, and 2061 cm-1. The FTIR spectra display two isotope-dependent bands at 2040 and 2061 cm-1. We assign the band at 419 cm-1 to ν(Fe−N3−CuB) and the bands at 2040 and 2061 cm-1 to νas(N3). The observation of two νas(N3) modes suggests that the azide ion binds to two different enzyme conformations, both forming bridging complexes with the binuclear center. Comparison of the FTIR data of the azide-bound cytochrome bo 3 and cytochrome a a 3 complexes reveal that there are quantitative differences in the structure of the heme o 3−CuB and heme a 3−CuB binuclear pockets upon azide binding. The present data on the vibrational frequencies of the azide-bound cytochrome bo 3 complex do not support the recent proposal that azide binds as a terminal ligand to CuB (Little, R. H.; Cheesman, M. R.; Thomson, A. J.; Greenwood, C.; Watmough, N. J. Biochemistry 1996, 35, 13780−13787) but are more reasonably interpreted to conclude that azide functions as a bridge between heme o 3 and CuB.

Copper Azide Confined Inside Templated Carbon Nanotubes

“…The weak shoulder peak at 2356 cm −1 is due to the physisorbed CO 2 . Raman spectroscopy of the encapsulated copper azide samples placed on a Si wafer showed the typical Cu–N=N + =N − vibrational modes (both strong and shoulder peaks in Figure 5b) in agreement with other azide compounds 18, 19. The observation of two asymmetric modes of N 3 at 2043 and 2177 cm −1 suggests that the azide ion binds to both Cu (I) and Cu (II).…”

“…The formation of the various copper azide phases is evident from the asymmetric azide peaks at 2091 and 2126 cm −1 ,18 in the FTIR spectrum of the copper azide filled CNT sample ( Figure ). The shoulder peak at 1574 cm −1 represents the COO − asymmetric stretching vibration and the broad band at 3230 cm −1 is the characteristic O‐H bending vibration.…”

Structural Stability and Vibrational Analyses of Haloselenonyl Azides, XSeO2-NNN, where X is F, Cl, Br

“…The very high reactivity and the application of organoazides in synthetic chemistry and many important industries [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] has drawn the attention to investigate the structure and conformational behavior of vinyl azide, CH2=CH-NNN [37] and formyl azide, CHO-NNN [38], by DFT and ab initio MP2 calculations. Both molecules were predicted to have a cis/trans conformational equilibrium with the gauche form being the transition state.…”

Enzymatic production of atranorin: a component of the oak moss absolute by immobilized lichen cells

“…2A) revealed the production of atranorin (retention time value 41.60 min) and evernic acid (retention time value 33.43 min), as well as the appearance of peaks corresponding to usnic acid (retention time 49.15 min) and chloroatranorin (retention time 43.55 min) and other minor peaks, presumably corresponding to undetermined precursors or catabolites. However, when sodium azide, a well‐known inhibitor of several oxidases [19, 20], was included in the oxygenated incubation medium containing NADH, the peak of usnic acid was newly detected and, in addition, a new peak appeared with a retention time value of 17.24 min (Fig. 2B) after 10 days.…”