Work

At the end of the 19th century, it became clear that biochemical processes do not necessarily require living cells, but are driven by special substances, enzymes, formed in cells. However, it remained to be seen how pure forms of these enzymes could be isolated. James Sumner studied the enzyme urease, which breaks down urea into ammonia and carbon dioxide. In 1926 he succeeded in isolating crystals with high activity from a kind of bean. Continued research indicated that the crystals were composed of a pure form of urease and that urease is a protein.