Aspergillus nuclease S1

Aspergillus Nuclease S1

Aspergillus nuclease S1 is an enzyme derived from the fungus Aspergillus oryzae. It is a single-strand specific endonuclease that is widely used in molecular biology for its ability to cleave single-stranded DNA and RNA. This enzyme is particularly useful in the analysis of nucleic acid structures and in the mapping of RNA secondary structures.

Structure and Function

Aspergillus nuclease S1 is a glycoprotein with a molecular weight of approximately 38 kDa. It is composed of a single polypeptide chain and contains several disulfide bonds that contribute to its stability. The enzyme exhibits optimal activity at acidic pH, typically around pH 4.5, and requires the presence of divalent cations such as zinc or magnesium for its catalytic activity.

The primary function of Aspergillus nuclease S1 is to cleave single-stranded regions of nucleic acids. It does so by hydrolyzing the phosphodiester bonds, resulting in the formation of 5'-phosphorylated and 3'-hydroxylated ends. This specificity for single-stranded regions makes it an invaluable tool for studying the structure of DNA and RNA, as it can be used to identify regions of secondary structure by selectively degrading unpaired nucleotides.

Applications in Molecular Biology

Aspergillus nuclease S1 is used in a variety of molecular biology applications, including:

• S1 nuclease mapping: This technique is used to determine the start and end points of RNA transcripts. By hybridizing RNA with a complementary DNA probe and treating the hybrid with S1 nuclease, researchers can identify the boundaries of the RNA by analyzing the protected DNA fragments.

• DNA footprinting: S1 nuclease can be used to study protein-DNA interactions by identifying regions of DNA that are protected from nuclease digestion due to protein binding.

• RNA structure analysis: The enzyme is used to probe the secondary structure of RNA by cleaving single-stranded regions, allowing researchers to map the structure of RNA molecules.

Biological Source

Aspergillus nuclease S1 is derived from Aspergillus oryzae, a filamentous fungus commonly used in the production of traditional Asian foods such as soy sauce and sake. The enzyme is purified from the culture filtrates of this organism and is commercially available for research purposes.

Safety and Handling

As with all enzymes, proper safety precautions should be taken when handling Aspergillus nuclease S1. It should be stored at recommended temperatures to maintain its activity and should be handled using appropriate personal protective equipment to avoid inhalation or contact with skin and eyes.

Also see

• Endonuclease
• Exonuclease
• Nuclease protection assay
• RNA secondary structure