P. aeruginosa azurin

His35 to ligated His46 may be important in an electron transfer role or in His35 exercising some conformational control of the active site. The reduction potential of P. aeruginosa azurin increases from 300 mV (pH 8) to 360 mV (pH 5), which is believed to be related to His35 protonation. A pK of 6.6 is observed for this process, or alternatively pK s for azurin in the oxidized (6.1) and reduced (7.2) forms can be obtained [56]. 

Fig. 5.39. Schematic drawing of the active site of P. aeruginosa azurin, spinach plastocyanin and cucumber stellacyanin (H = histidine, C = cysteine, M = methionine, G = glycine, Q = glutamine) (adapted from [198]).

Fig. 5.40. (A) H NMR spectra at 298 K of oxidized spinach plastocyanin at 800 MHz (adapted from [117]). (B) Far downfield region of the H NMR spectra of oxidized (i) P. aeruginosa azurin, (ii) spinach plastocyanin and (iii) cucumber stellacyanin containing signals not observable in direct detection (adapted from [198]). The positions and line widths of the signals were obtained using saturation transfer experiments by plotting the intensity of the respective exchange connectivities with the reduced species as a function of the decoupler irradiation frequency.

Fig. 5.8. Three-dimensional structure of P. aeruginosa azurin. Coordinates from ref. [80] and Brookhaven Data Bank. Graphic representation by Molscript [66], The copper atom is indicated by the large sphere at the top, the disulphide group by the two smaller, lightly...

Fig. 5.9. Left In situ (open circuit) AFM image of pre-adsorbed P. aeruginosa azurin on Au(lll). 50 mM ammonium acetate, pH = 4.65 (isoelectric point). Right Three-dimensional view of the same image (other details in ref. [83]).

Figure 3 Ribbon representation of the peptide backbone in P. aeruginosa azurin. The Cu cofactor and its hgands are shown in black...

Figure 4 Distance dependence of driving-force-optimized electron tunneling times in Ru-labeled P. aeruginosa azurin. The sohd line is the distance decay predicted by the tunneling-pathway model for ET along an ideal 8-strand ( 8 = 1.0 A ). The dashed line is the best fit to the data fi =. A ) ...

Figure 17 Low-temperature (77 K) RR spectrum of P. aeruginosa azurin obtained with 647.1-mn excitation wavelength and structural drawing of the active site showing distances (A) to the three strong (Cysl 12, His46, Hisll7) and two weak ligands (Metl21, Gly45)...

Figure 19 Low-temperature (77 K) RR spectra of P. aeruginosa azurins from cells grown on [ S]- or p S]sulfate, excited at 647.1 (WT) and 568.2 nm (mutants). Italic numbers show the [i ( S) — i ( S)] band shifts...

Figure 20 RR spectra of P. aeruginosa azurin and its [C/3D2] Cysl 12-labeled protein obtained at 77 K with 647.1-nm excitation...

Substitution of amino acid residues at the metal center by site-directed mutagenesis can alter the geometry and properties of the active site, thus allowing elucidation of the minimal requirements for the proper functioning of the metalloprotein. As an example. Figure 21 and Table 5 show the results of RR scattering from a series of P. aeruginosa azurins in which the active site Met 121 has... 

Table 5 Optical spectral parameters and Cu-Scys RR stretching frequencies for P. aeruginosa azurins and their complexes with exogenous ligands ...

Table 6 Ligand vibrations of P. aeruginosa azurin derivatives ...

Figure 27 Room temperature UV-visible spectra of (a) native P. aeruginosa azurin and its (b) Ni(II)-, and (c) Co(ll)-substituted derivatives...

Figure 28 RR spectra (77 K) of Ni(II)-substituted P. aeruginosa azurin obtained with indicated excitation wavelengths. Asterisks indicate ice Raman bands...

Figure 29 Low-temperature (77 K) RR spectra of P. aeruginosa azurin obtained in the(A) 100-500cm" and (B) 500-1000cm" regions on (a) native Cu(ll) protein (647.1-nm excitation) and (b) its Ni(ll)-substituted derivative (413.1-nm excitation). Asterisks indicate ice Raman bands...

Figure 30 Effects of Ni-isotope substitution on the 200-430 cm" RR spectrum of P. aeruginosa azurin Italic numbers show the [v( Ni) — v( Ni)] band shifts...

Native and Ni(II) azurin data from Czemuszewicz et al Native and Ni(II) azurin II data from Hannan et al7 Native and Ni(II) stellacyanin data from Musci et al Assignments based on NCA calculations of P. aeruginosa azurin. Contain contributions from peaks at 262/268 and 280/286 cm , respectively. Boldface numbers indicate the RR peaks with the greatest intensity sh = shoulder. Possibly overlapping bands. 

Azurins are found in the respiratory chains of various denitrifying bacteria, where their role is to transport electrons between cytochrome C551 and C5d ochrome oxidase. The kinetics of the reaction of P. aeruginosa azurin and cytochrome C551 has been studied (39,40). The role of... 

Plate 17.10 (a) Stereo view of the active-site structure of P. aeruginosa azurin (PDB 4azu) [46]. (b) Tube diagram of the P. aeruginosa azurin showing the section of protein that was contributed by intein ligation. 

Figure 17.10 (a) Stereo view of the active-site structure of P. aeruginosa azurin (PDB 4azu)... 

Figure 2.12 Overview of three-dimensional structures and in situ STM images of metalloproteins representative of the three ET protein classes characterized by single-crystal PFV and in situ STM to single-molecule resolution, (a) Blue copper protein P. aeruginosa azurin (PDB 4AZU) [94] ...

Au-Nanopartide Hybrids of Horse Heart Cytochrome c and P. aeruginosa Azurin... 

Figure 2.19 Cyclic voltammogram and in situ STM images of P. aeruginosa azurin-AuNP hybrid, (a) Schematic of the hybrid and of P. aeruginosa azurin alone on 4,4 -biphenyldithiol-modified Au(111) electrode, (b) Cyclic voltammogram showing the duality caused by the presence of both hybrid and azurin alone on the surface. The outer pair of voltammetric peaks represents azurin, the inner pair the...

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