Involved in the degradation of pyridoxine (vitamin B(6)). Catalyzes the oxidation of 4-pyridoxic acid to 5-formyl-3-hydroxy-2-methylpyridine-4-carboxylate. 4-pyridoxate + A = 5-formyl-3-hydroxy-2-methylpyridine-4-carboxylate + AH2 kcat is 11 sec(-1). Optimum pH is 8.5. Optimum temperature is 30-35 degrees Celsius. Cofactor degradation; B6 vitamer degradation. Monomer. Membrane-bound. The N-terminus is blocked. Belongs to the GMC oxidoreductase family.