Helmut Ankel

[50] UDP-glucuronic acid decarboxylase

Publisher Summary This chapter discusses the synthesiss of uridine diphosphate (UDP)-glucuronic acid decarboxylase. UDP-D-xylose formed from UDP-D-glucuronic acid is hydrolyzed in acid. The xylose released is determined colorimetrically. One unit is defined as that amount of enzyme which produces 1 micromole of UDP-D-xylose per minute at 37°; specific activity is expressed as units per milligram protein. The assay method of the enzyme from Cryptococcus laurentii is also described in the chapter. The reaction mixtures contain 10 μl of 0.01 M NAD. The reagents used, procedure followed, and the steps involved in the purification are also discussed in the chapter. The enzyme is relatively stable for up to one month at –10 °. UDP-D-xylose and CO 2 are the only reaction products. The enzyme preparation has no UDPG or UDP-D-glucuronic acid pyrophosphorylase activity. The optimum pH is between 6.8 and 7.0. The activity falls to approximately 75% of maximum at pH 6.0 and 7.8.