Heat precipitation
The heat precipitation is a biochemical method for the precipitation of proteins from a solution using heat.
principle
Heating denatures proteins , e.g. B. by heating for five minutes at 95 ° C and then cooling on ice. Long -term heating can lead to deamidation of glutamines and asparagines in proteins. In human proteins, the denaturation of individual proteins begins at 42 ° C. The heat precipitation changes the native protein folding , which means that biological activity is lost and most proteins become less soluble. In the case of proteins from hen's egg whites (a mixture of different proteins), the solubility drops above the denaturation temperature of about 60 to 70 ° C to about 10 to 20% of the solubility at 40 ° C. Thermostable proteins (e.g. thermostable DNA polymerases ) are not precipitated, but remain in solution. This can be used for the selective purification of thermostable proteins. Heat precipitation is used, among other things, in heat stabilization and heat fixation .
Individual evidence
- ^ A b c Alfred Pingoud : Working methods of biochemistry. Walter de Gruyter, 1997, ISBN 978-3-110-16513-5 , p. 55.
- ^ GM Hall: Methods of Testing Protein Functionality. Springer Science & Business Media, 1996, ISBN 978-0-751-40053-3 , p. 41.
- ↑ Kenji Watanabe, Tsukasa Matsuda, Ryo Nakamura: Heat-Induced Aggregation and Denaturation of Egg White Proteins in Acid Media. In: Journal of Food Science. 50, 1985, p. 507, doi : 10.1111 / j.1365-2621.1985.tb13438.x .