Ribonuclease (RNase) Inhibitors

RNase inhibitors are recombinant enzymes that inhibit the activity of RNases. Since RNases are ubiquitous in the laboratory environment—on your skin, in the air, on anything touched by bare hands, or on anything left open to the air—it is important to make an effort to prevent or eliminate RNase contamination, which can be done with the use of RNase inhibitors.

RNase inhibitors are typically sold in units, and one unit (depending on the RNase inhibitor you use) is defined as the amount of protein to inhibit 5 ng RNase A.

Based on experimental design and the input amount of RNA, the amounts of RNase inhibitor to use will vary. A quick calculation will need to be made first to decide the amount required for your experiment. Note: What's in a unit? Most enzymes and proteins are sold based upon their unit activity. Looking closely at not only the manufacturer's unit definition, but more importantly at their unit assay, generates a better understanding of how the product will function in your specific application. Unfortunately, more often than not, the attempt to apply an established unit assay to your own system can lead to issues because unit assays are designed to quantitate a specific function of the product. Such is the case for ribonuclease inhibitors.

The traditional unit assay for ribonuclease inhibitors has been the cyclic cytidine monophosphate (CMP) assay. While this assay does demonstrate inhibition of RNase A, it is limited in that it provides only an indirect measure of RNA degradation. Because cCMP is an artificial substrate for RNase, its hydrolysis does not always correlate with actual RNA degradation. In addition, this assay can only be used for RNase A-type ribonucleases and their inhibitors because cCMP is not a substrate for many other ribonucleases.

In addition, some manufacturers define a unit via a functional assay that directly measures the ability of the inhibitor to block RNA degradation. A radiolabeled RNA is exposed to various RNases with and without the inhibitor. The results are analyzed on a polyacrylamide gel to determine the degree to which RNA degradation is inhibited. This functional assay provides direct information about the inhibitor's ability to block RNA degradation.

Nuclease inhibitors encompass both RNase and DNase inhibition. We offer several nuclease (which includes DNase and RNase) inhibitors: Invitrogen SUPERase•In RNase Inhibitor, RNaseOUT Recombinant Ribonuclease Inhibitor, RNAsecure RNase Inactivation Reagent, and RNase Inhibitor (RI). See which inhibitor or reagent is right for your research by viewing the selection guide below:

	SUPERase•In RNase inhibitor	RNaseOUT recombinant ribonuclease inhibitor	RNAsecure RNase inactivation reagent	RNase Inhibitor (RI)	RNase Inhibitor (RI), cloned
Mechanism	This is a protein-based inhibitor of non-human origin that non-covalently binds and inhibits the most common and troublesome RNases, including RNase A, B, C, 1, and T1	This is a non-competitive inhibitor of pancreatic-type ribonucleases such as RNase A	This is a non-enzymatic reagent that will irreversibly inactivate RNases in solution	This is a 50 kDa recombinant enzyme used to inhibit RNase activity	This is a recombinant human protein produced in E. coli and inhibitor of neutral pancreatic RNase A type enzymes
Sizes available	2,500 (20 U/μL) units 10,000 (20 U/μL) units	5,000 units	1 mL 10 mL	2,000 units (Applied Biosystems)	1,000 units (Invitrogen) 2,500 units (Ambion) 10,000 units (Ambion)