DETERMINATION OF GUANASE ACTIVITY IN NORMAL AND PATHOLOGICAL SERA BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A simple HPLC assay for serum guanase based on the direct determinatio n of enzymatically formed xanthine was applied to normal and pathologi cal sera. The procedure is sensitive, precise (CV below 5%) and suitab le for routine purposes, and the method requires only 50 mu L of sampl e. Using this method the reference range as determined from the sera o f 40 healthy adult controls is 0-1.1 U/L. In patients with various liv er diseases serum guanase activities were found to be increased 5- to 50-fold compared with the normal mean value.