FT-IR STUDY OF PYRIDOXAL-PHOSPHATE

Films of pyridoxal phosphate were studied using FT-IR spectroscopy at different pH values using the ATR (attenuated total reflection) techni que. With increasing pH of the films, very intense changes in the spec tra were observed due to concentration changes of the hydrogen-bonded species N ... H-O-P reversible arrow N+-H ...O--P, O-... H-O-P reversi ble arrow O-H ...O--P and (P-O ... H ... O-P)(-). The spectra are char acterised by pH-dependent continua which indicate that the above menti oned hydrogen bridges show very large proton polarizability. Other str iking features in the spectra are due to the change in tautomeric equi librium between aldehyde and ketol forms. (C) 1998 Elsevier Science B. V.