Dear Albert, please have a look at
dx.doi.org/10.1007/s11010-008-9826-1 Good luck! Karsten --------------------------------------- Dr. Karsten Niefind Institute of Biochemistry Department of Chemistry University of Cologne Zuelpicher Strasse 47 D-50674 Cologne tel.: +49/221/470-6444 fax: +49/221/470-5092