Ribonuclease Inhibitor, Placenta (RI, RNase Inhibitor)

Dry Ice

Purified

Storage Buffer:
20mM HEPES-KOH (pH 7.5), 50mM KCl, 5mM DTT and 50% glycerol.

Unit Definition:
One unit is the amount of enzyme required to inhibit by 50% the activity of 5ng of RNase A at 25°C (This inhibitor activity is determined by its ability to inhibit hydrolysis of cyclic 2', 3'-CMP by RNase A).

Quality Control:
Nuclease activity was not detected in any of the following cases, as judged from the intact gel electrophoresis:
1. After incubation of 1ug of λ DNA-Hind III fragments with 300 units of enzyme for 24 hours at 37°C
2. After incubation of 1ug of pBR322 DNA with 300 units of enzyme for 24 hours at 37°C
3. Migrates as a single band of 50 kd in SDS-polyacrylamide gel electrophoresis.

Note: Enzyme inhibits in a wide pH range, but most strongly at pH 7-8. Requires DTT of at least 1 mM to be active.

Storage and Stability:
May be stored at 4°C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20°C. Aliquots are stable for at least 6 months at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.