| Urease occurs in many bacteria, several species of yeast and a number of higher plants. Two of the best sources are Jack beans (Canavlia ensiformis) from which it has been crystallized and thoroughly studied and Bacillus pasteurii. Urease catalyzes the hydrolysis of urea. The molecular weight of the jack bean enzyme is 480kD, with an optimum pH of 6.0. It is inhibited by heavy metals. Unit Definition: 1 unit oxidizes one micromole of NADH per minute at 25C, pH 7.6. The hydrolysis of urea is measured by coupling ammonia production to a glutamate dehydrogenase reaction. Activity: 45 units per mg dry weight A280: As Reported Ammonia: As Reported Storage and Stability: Lyophilized powder may be stored at -20C. Stable for 6 months after receipt at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer. |
