Abstract
Partially purified renin has been prepared in several laboratories from NaCl or cold acetone extracts of the kidney cortex. 1-4 Recently modifications in our original extraction procedure 2 have been introduced which eliminate many of the more cumbersome manipulations involved, with considerable saving of time, without sacrificing the relative high potency of the final product.
Extraction Procedure. Demedullated kidneys are ground, frozen, and, before thawing, reground into 2% NaCl solution (10 liters to 3 kg tissue). It is possible to use fresh, unfrozen kidneys, but the extraction appears to be less complete. After the salt extract has been stored for 24 hours under toluene, the meat sludge is removed by straining and centrifuging (Sharpies). The pH is then lowered to 4.5. After an interval of 12 to 24 hours to insure complete precipitation, the heavy precipitate is removed by centrifuging (Sharpies) and filtering through Hyflo Super-Cel.† For easier handling in subsequent procedures, the filtrate, adjusted to pH 6.8, is concentrated in vacuo (maximum temperature 45°C) to a volume of 1 liter. The concentrate is filtered, 100 g NaCl are added and the pH is lowered to 2.0. The heavy precipitate is removed on a filter cake of Hyflo which is then suspended in 2 liters of water. After the pH is raised to neutrality and the suspension thoroughly mixed by a motor stirrer for about 30 minutes, Hyflo and any insoluble precipitate are filtered off and discarded. The filtrate is saturated with solid NaCl and the pH again lowered to 2.0. The precipitate is removed on a filter cake and redissolved in 500 cc N/10 acetate buffer at pH 5. As before, insoluble residue is discarded.
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