Abstract

The structure of zinc (II)-substituted cytochrome c (Zn-Cytc), recently resolved by NMR, suggested that Zn is in an unusual coordination with six ligands (Anni et al., Biochemistry 1995, 34, 5744-5753). Furthermore, fluorescence line narrowing spectroscopy has shown that Zn becomes penta-coordinated upon protein unfolding. An hexa-coordinated state of Zn in Cytc is unique since there are no examples of any hexa-coordinated Zn-proteins, and there are no hexa-coordinated Zn-porphyrins in solution. Moreover, the particular coordination of Zn with five nitrogens and one sulfur ligand in Cytc is surprising, because even among the Zn organic compounds that are hexa-coordinated (27% of the 428 crystal structures) none is of the type (N) 5-Zn-(S) 1. Taken together these findings point to a tight protein modulation of the binding preference and strength of Zn to its ligands in Cytc. The Zn-edge extended X-Ray absorption fine structure H(EXAFS) studies of Zn-Cytc were undertaken in order to define the Hcentral metal environment, specifically the distances of the Zn metal Hto its ligands and their nature. Both native and guanidine-denatured HZn-Cytc at neutral pH were measured, alongside with the corresponding HFe(III)-Cytc references. Sets of experimental EXAFS data were fit to Htheoretical curves (FEFF 6.01) using a novel refinement procedure were Hobtained. This data analysis establishes the coordination of the Zn Hsite in Cytc: an hexa-coordinated Zn in the native protein Henvironment (Zn-Np=2.052A, Zn-Met80 (SD) =2.34A, Zn-His(NE)=2.371A) Hand a mixture of penta-coordinated Zn states in the denatured sample H(Zn-Np=2.10A, Zn-His(NE) =2.10-2.20A). Fe-cyt-c data showed close Hagreement with crystallographic data. Analysis of denatured Hcytochrome-c is continuing.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Biotechnology Resource Grants (P41)
Project #
2P41RR001633-16
Application #
6120380
Study Section
Project Start
1998-09-30
Project End
1999-08-31
Budget Start
Budget End
Support Year
16
Fiscal Year
1998
Total Cost
Indirect Cost

  Institution

Name
Albert Einstein College of Medicine
Department
Type
DUNS #
009095365
City
Bronx
State
NY
Country
United States
Zip Code
10461

  Publications

Vongsvivut, Jitraporn; Fernandez, Jason; Ekgasit, Sanong et al. (2004) Characterization of supported cylinder-planar germanium waveguide sensors with synchrotron infrared radiation. Appl Spectrosc 58:143-51
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Huang, Raymond Y; Miller, Lisa M; Carlson, Cathy S et al. (2003) In situ chemistry of osteoporosis revealed by synchrotron infrared microspectroscopy. Bone 33:514-21
Rashidzadeh, Hassan; Khrapunov, Sergei; Chance, Mark R et al. (2003) Solution structure and interdomain interactions of the Saccharomyces cerevisiae ""TATA binding protein"" (TBP) probed by radiolytic protein footprinting. Biochemistry 42:3655-65
Uchida, Takeshi; Takamoto, Keiji; He, Qin et al. (2003) Multiple monovalent ion-dependent pathways for the folding of the L-21 Tetrahymena thermophila ribozyme. J Mol Biol 328:463-78
Taylor, Colleen M; Watton, Stephen P; Bryngelson, Peter A et al. (2003) Inner-sphere complexation of cobalt(II) 2,9-dimethyl-1,10-phenanthroline ([Co(neo)]2+) with commercial and sol-gel derived silica gel surfaces. Inorg Chem 42:312-20
Dewan, John C; Feeling-Taylor, Angela; Puius, Yoram A et al. (2002) Structure of mutant human carbonmonoxyhemoglobin C (betaE6K) at 2.0 A resolution. Acta Crystallogr D Biol Crystallogr 58:2038-42
Kiselar, J G; Maleknia, S D; Sullivan, M et al. (2002) Hydroxyl radical probe of protein surfaces using synchrotron X-ray radiolysis and mass spectrometry. Int J Radiat Biol 78:101-14
Swisher, Jennifer F; Su, Linhui J; Brenowitz, Michael et al. (2002) Productive folding to the native state by a group II intron ribozyme. J Mol Biol 315:297-310
Dhavan, Gauri M; Crothers, Donald M; Chance, Mark R et al. (2002) Concerted binding and bending of DNA by Escherichia coli integration host factor. J Mol Biol 315:1027-37

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