tokens: We studied a thiamine - dependent enzyme , transketolase , from fibroblasts of a diabetic patient who developed Wernicke ' s encephalopathy when treated with tolazamide , in order to delineate if this patient also had transketolase abnormality [ high Km for thiamine pyrophosphate ( TPP ) ] , as previously reported in postalcoholic Wernicke - Korsakoff syndrome .