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CAN GEOMETRICAL DISTORTIONS MAKE A LACCASE CHANGE COLOR FROM BLUE TO YELLOW? pdb ID Resolution (Å) Cu-S Cu-N 1 Cu-N 2 SCu-NC(1) SCu-NC(1) 2X88 1.80 2.21 2.08 2.07 -5 -54 2ZWN 1.70 2.24 2.08 1.99 -5 -62 2.25 2.10 2.06 1 -67 2.27 2.08 2.03 -2 -66 3CG8 2.68 2.20 2.01 1.89 -28 -48 2.16 2.01 1.91 -28 -49 2.19 1.97 1.97 -27 -52 3DIV 1.76 2.09 2.52 2.21 29 -46 3DKH 2.40 2.19 2.16 2.28 22 -60 2.12 2.14 2.08 9 -54 3FPX 1.80 2.24 2.01 2.05 6 -38 3FU7 1.67 2.13 2.03 2.08 -16 -50 2.19 2.00 2.05 -15 -54 3FU8 1.80 2.06 2.10 2.11 -26 -49 2.13 2.04 1.99 -18 -51 3FU9 2.00 2.13 1.81 2.37 -10 -54 2.01 2.06 2.28 -22 -85 3KW7 3.44 2.13 2.14 2.05 3 -71 2.08 2.06 2.12 -8 -73 Average 2.20 2.07 2.08 -7 -50 CONCLUSIONS Using computational methods, torsion and elongation-type deformations have been identified, which allow a “blue” tri-coordinated type 1 copper center to apparently lose its characteristic 600-nm band responsible for its blue color both by shifting it by more than 200 nm, and, in some cases, by decreasing the extinction coefficients. However, DFT calculations suggest that such distortions might also be detectable with EPR spectroscopy. Last but not least, we note that some of the distortions, while perfectly feasible in the small models employed in the present study, may well leave the site too exposed to a fourth ligand and thus may entail a lack of stability that would preclude facile experimental observation of such a distorted center. EXPERIMENTAL SECTION All data reported here are single-point energy calculations; attempts to optimize the geometry at the DFT level led to significant deviations from the initial conformations of the ligands. ZINDO/S-CI calculations were performed in the Hyperchem software package [12]. An excitation window of 20 eV was chosen; a ~ 600-nm band of reasonable intensity was found 237
ALEXANDRU LUPAN, CSONGOR MATYAS, AUGUSTIN MOT, RADU SILAGHI-DUMITRESCU to already be computed with windows as low as 14 eV, and its wavelength appeared to converge towards a stable value as the excitation window was gradually increased up to 20 eV. DFT calculations on selected structures were performed in the Gaussian09 software package [13], M062X/6- 311+G** using the SCF=Tight option. ACKNOWLEDGMENTS This work was supported by CNCSIS-UEFISCDI, projects PNII - ID_PCCE_140/2008, 312/2008 and by a PhD scholarship to AM (Contract POSDRU/88/1.5/S/60185 – “Innovative doctoral studies in a knowledge based society”). Profs D.A. Svistunenko (University of Essex) and H.A. Heering (Leiden University) are thanked for helpful discussions. REFERENCES 1. L. M. Mirica, X. Ottenwaelder, T. D. Stack, Chemica. Reviews, 2004, 104, 1013. 2. E. I. Solomon, U. M. Sundaram, T.E. Machonkin, Chemical Reviews, 1996, 96, 2563. 3. N. N. Pozdnyakova, J. Rodakiewicz-Nowak, O. V. Turkovskaya, Journal of Molecular Catalalysis B: 2004, 30,19. 4. G. Palmieri, P. Giardina, C. Bianco, A. Scaloni, A. Capassoi, G. Sannia. Journal of Biological Chemistry, 1997, 272, 31301. 5. A. A. Leontievsky, T. Vares, P. Lankinen, J. K. Shergill, N. M. Pozdnyakova, N. Kalkkinen, L. A. Golovleva, R. Cammack, C. F. Thurston, A. Hatakka. FEMS Microbiological Letters, 1997, 156, 9. 6. A. A. Leontievsky, N. M. Myasoedova, B. P. Baskunov, N. N. Pozdnyakova, T. Vares, N. Kalkkinen, A. I. Hatakka, L. A. Golovleva, Biochemistry (Moscow), 1999; 64, 1150. 7. D. A. Wood, Journal of General Microbiology, 1980, 117, 327–338. 8. W. A. Edens, T. Q. Goins, D. Dooley, J. M. Henson, Applied and Environmental Microbiology, 1999, 65, 3071. 9. O. M. H. Vries, W. H. C. F. Kooistra, G. H. Wessels, Journal of General Microbiology, 1986, 132, 2817. 10. K. Min, Y. H. Kim, Y. W. Kim, H. S. Jung, Y. C. Hah, Archives of Biochemistry and Biophysics, 2001, 392, 279. 11. A. C. Moţ, M. Pârvu, G. Damian, R. Silaghi-Dumitrescu, manuscript in preparation. 12. Hyperchem(TM) Molecular Modelling System, Release 5.01 for Windows, Hypercube, Inc. 1998 13. M. J. Frisch et al, Gaussian 09; Gaussian, Inc., Wallingford CT, 2004 238
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CHEMIA 3/2011
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CORINA COSTESCU, LAURA CORPAŞ, NIC
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Studia Universitatis Babes-Bolyai C
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MONICA BAIA, MONICA SCARISOREANU, I
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STUDIA UBB CHEMIA, LVI, 3, 2011 (p.
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SPECTROSCOPIC EVIDENCE OF COLLAGEN
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