The amino acid composition of jack-bean urease.

Analyses were carried out on twice-recrystallized freeze-dried urease (Bailey & Boulter, 1969) that had previously been dialysed for 24hr. in the cold against running tap water, and then for 24hr. against three changes of deionized water. Acid hydrolysis of urease (5mg.) was carried out at 1100 in evacuated heavy-walled Pyrex tubes with threetimes-redistilled 5-7M-hydrochloric acid at a concentration of 0-2ml. of acid/mg. of protein. The hydrolysis procedure was otherwise similar to that described byMoore & Stein (1963). The hydrolysate was applied to the column in 0M-hydrochloric acid. Duplicate hydrolysates were analysed on a Technicon AutoAnalyzer with the 18hr. elution system.