1. Department of Chemistry, University of Warsaw, 1 Pasteur St, PL-02093 Warsaw, Poland;
2. Departments of Biological Structure, University of Washington, Seattle, Washington 98195;
3. Biochemistry, University of Washington, Seattle, Washington 98195;
4. Ophthalmology, University of Washington, Seattle, Washington 98195;
5. Chemistry, University of Washington, Seattle, Washington 98195;