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Denaturation of Proteins by Urea and Related Substances*

1930; Nature Portfolio; Volume: 126; Issue: 3175 Linguagem: Inglês

10.1038/126383a0

1476-4687

Frederick Gowland Hopkins,

Protein purification and stability

UPON the facts enumerated the following simple method of determining the degree and rate of denaturation is based. A measured sample of the ureaprotein mixture is diluted with ten times its bulk of water, and to secure complete precipitation of the denatured product a small quantity (say 1 gm. per 100 c.c.) of ammonium sulphate is added, and if precipitation is not immediate a small amount of acetic acid. When the precipitate has settled out it is filtered and washed, or better centrifuged and washed, until free from sulphate, when it will also be free from undenatured protein. The precipitate is then transferred to a tared basin, dried and weighed. The method is trustworthy and gives consistent results. If the protein left in solution after the precipitate has been removed be thrown out by saturation with ammonium sulphate, it will be found to be wholly resoluble in water; that is to say, it is undenatured albumin.