Polarographic behaviours of pyridoxal-homocysteine (PAL-HCySH) were studied by the direct current method and the following results were obtained. (1) In the acidic or neutral solution, two cathodic waves were clearly observed and it was found to be controlled with diffusion process. At higher pH value, the hydrolysis occurs and the wave of pyridoxal appears on polarographic waves. (2) Electrophoresis and spectrophotometry of the substances produced by means of potential electrolysis were determined to clarify the reduction course of PAL-HCySH. It was indicated that the first cathodic wave of PAL-HCySH was attributed to the hydrogenalytic fission of the C-S bond to give N-pyridoxyl-homocysteine (I). The second wave was due to hydrogenolysis of the C-N bond in (I) to afford 4-deoxypyridoxine.
