Restriction enzymes recognize specific nucleotide sequences and cleave DNA molecules at a position either within or outside their recognition site. These enzymes are important tools for numerous applications, including studies of DNA primary structure and recombinant DNA technology. More than 3800 restriction enzymes, exhibiting ~260 different specificities, have been isolated.
Since 1977, Fermentas has discovered approximately 30% of all known restriction enzymes. We are a leading global enzyme manufacturer, offering <200 commercial conventional and 176 FastDigest® restriction enzymes. We actively screen for new restriction enzymes and are continuously discovering new restriction enzyme specificities. Fermentas is the supplier of choice both for classic restriction enzymes and for new unique enzymes which are not supplied by other companies.
Fermentas restriction enzymes, both FastDigest® and conventional, are the only restriction enzymes on the market manufactured in classified (class D, EU classification) controlled environment facilities under the latest ISO9001:14001 quality and environmental management systems.

PureExtreme® Quality – the industry's highest quality and performance – is further ensured by extensive quality control tests. Fermentas restriction enzymes pass all industry standard quality control assays, as well as the unique Labeled Oligonucleotide (LO) test which is the most sensitive test for the detection of trace activities of endodeoxyribonucleases, exodeoxyribonucleases and phosphatases.
We monitor all enzyme lots to ensure they meet these stringent quality control specifications right up to their expiry date.
The PureExtreme® Quality of Fermentas restriction enzymes ensures that the integrity of your DNA is not compromised, making them the enzymes of choice for even the most demanding applications.

Labeled Oligonucleotide (LO) Test – Fermentas has designed its unique LO test to achieve the highest sensitivity in detection of trace activities of endo-, exodeoxyribonucleases and phosphatases, ensuring the best quality and performance of our products. Single-stranded and double-stranded 5’-[³²P]-labeled synthetic oligonucleotides containing no recognition sites for restriction enzymes are used as substrates for the LO test. The labeled oligonucleotides are incubated with excess of restriction enzyme, separated on a polyacrylamide gel under denaturing conditions and analyzed by phospho-imaging. The presence of contaminating endo- and exodeoxyribonucleases results in the degradation of the labeled substrates, while decreased specific radioactivity indicates the presence of contaminant phosphatases. The restriction enzyme passes this quality control test if there is neither degradation of labeled oligonucleotides nor a decrease in specific radioactivity.

Figure 1. Labeled Oligonucleotide (LO) Test.
ss – single-stranded radiolabeled oligonucleotide
ds – double-stranded radiolabeled oligonucleotide
Pure enzyme – Fermentas NotI
Contaminated enzyme – competitor's NotI