Nickel(II)-substituted azurin I from Alcaligenes xylosoxidans as characterized by resonance Raman spectroscopy at cryogenic temperature
Fitzpatrick, MB; Czernuszewicz, RS
HERO ID
1840357
Reference Type
Journal Article
Year
2009
Language
English
PMID
| HERO ID | 1840357 |
|---|---|
| In Press | No |
| Year | 2009 |
| Title | Nickel(II)-substituted azurin I from Alcaligenes xylosoxidans as characterized by resonance Raman spectroscopy at cryogenic temperature |
| Authors | Fitzpatrick, MB; Czernuszewicz, RS |
| Journal | Journal of Biological Inorganic Chemistry |
| Volume | 14 |
| Issue | 4 |
| Page Numbers | 611-620 |
| Abstract | Metal-substituted blue copper proteins (cupredoxins) have been successfully used to study the effect of metal-ion identity on their active-site properties, specifically the coordination geometry and metal-ligand bond strengths. In this work, low-temperature (77 K) resonance Raman (RR) spectra of the blue copper protein Alcaligenes xylosoxidans azurin I and its Ni(II) derivative are reported. A detailed analysis of all observed bands is presented and responsiveness to metal substitution is discussed in terms of structural and bonding changes. The native cupric site exhibits a RR spectrum characteristic of a primarily trigonal planar (type 1) coordination geometry, identified by the nu(Cu-S)(Cys) markers at 373, 399, 409, and 430 cm(-1). Replacement of Cu(II) with Ni(II) results in optical and RR spectra that reveal (1) a large hypsochromic shift in the main (Cys)S --> M(II) charge-transfer absorption from 622 to 440 nm, (2) greatly reduced metal-thiolate bonding interaction, indicated by substantially lower nu(Ni-S)(Cys) stretching frequencies, (3) elevation of the cysteine nu(C( beta )-S) stretching, amide III, and rho (s)(C( beta )H(2)) scissors vibrational modes, and (4) primarily four-coordinated, trigonally distorted tetrahedral geometry of the Ni(II) site that is marked by characteristic nu(Ni-S)(Cys) stretching RR bands at 347, 364, and 391 cm(-1). Comparisons of the electronic and vibrational properties between A. xylosoxidans azurin I and its closely structurally related azurin from Pseudomonas aeruginosa are made and discussed. For cupric azurins, the intensity-weighted average M(II)-S(Cys) stretching frequencies are calculated to be nu(Cu-S)(iwa) = 406.3 and 407.6 cm(-1), respectively. These values decreased to nu(Ni-S)(iwa) = 359.3 and 365.5 cm(-1), respectively, after Ni(II) --> Cu(II) exchange, suggesting that the metal-thiolate interactions are similar in the two native proteins but are much less alike in their Ni(II)-substituted forms. |
| Doi | 10.1007/s00775-009-0475-y |
| Pmid | 19224256 |
| Wosid | WOS:000265397800011 |
| Is Certified Translation | No |
| Dupe Override | No |
| Comments | Source: Web of Science WOS:000265397800011 |
| Is Public | Yes |
| Language Text | English |
| Keyword | Resonance Raman spectroscopy; Azurin; Blue copper proteins; Cupredoxins; Type 1 copper |