Abstract
A transketolase assay is described which distinguishes transketolase activity from the overall ribose-5-phosphate utilization. The transketolase enzyme can be saturated and hence the activity can be expressed as international units of enzyme activity: micromoles per hour per milliliter of whole blood. Data are given on thiamindeficient and pair-fed control animals showing that the transketolase enzyme is sensitive to thiamin deficiency. Normal and deficient values are indicated.