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United States Biological


Single-Strand Nucleases :
Penicillium citrinumSingle-strand-specific nucleases act selectively on single-stranded nucleic acids and single-stranded regions in double-stranded nucleic acids. They are involved in recombination, repair and replication. Although more than 30 single-strand-specific nucleases from various sources have been isolated so far, only a few enzymes such as S1 Nuclease, P1 Nuclease, Bal 31 Nuclease, and Mung Bean Nuclease have been characterized to a significant extent.

Newsletter Bonus Special:
Nuclease P1

virion visualized by TEMNuclease P1 (Nuclease 5'-Nucleotidehydrolase, 3'-Phosphohydrolase) from Penicillium citrinum, a zinc dependent glyco-enzyme consisting of 270 amino acid residues, hydrolyzes both 3'-5'-phosphodiester bonds in RNA and heat denatured DNA and 3'-phosphomonoester bonds in mono- and oligonucleotides terminated by 3'-phosphate without base specificity. Nuclease P1 is capable of hydrolyzing single stranded DNA and RNA completely to the level of mononucleoside 5’-monophosphates. The enzyme does not attack double-stranded nucleic acids, especially in the presence of more than 400mM of sodium chloride at pH 6.0.

This month's Special:
Good's Buffers

H2010 HEPES, M3000 MES, P4200 PIPES

HEPES, MES, and PIPES are three of the biological buffers (zwitterionic) designed by Good, et al., and typically referred to as Good’s buffers. They are useful in cell culture media formulations. Selection of biological buffer systems should include the following criteria: exclusion by biological membranes, low absorption between 240 and 700nm, chemical stability, and stable to temperature and concentration changes.


MES Structure

Nuclease P1
from Penicillium Citrinum

Nuclease P1 (EC3.1.30.1; Nuclease 5'-Nucleotidehydrolase, 3'-Phosphohydrolase) is an extracellular enzyme first identified by Kuninaka, et al.  in 1957 in an aqueous extract of the mold Penicillium citrinum. It has been shown by Fujimoto, et al (1974) to be a single strand-specific nuclease which exhibits high selectivity for single-stranded nucleic acids and single-stranded regions in double-stranded nucleic acids.  Nuclease P1 is one of the most widely used single-strand specific nucleases in molecular biology; its selective activity has found useful applications in studies on nucleic acid structure.



mung bean sproutsMung Bean Sprouts

A Sampling of
Other USBio Nucleases:

Micrococcal Nuclease (S7) S. aureus (Strain Foggi)
Micrococcal nuclease is the extracellular nuclease of S. aureus. It catalyzes preferential endohydrolysis of nucleic acids at adenylate, uridylate, deoxyadenylate or thymidylate-rich sites, yielding 3I nucleotides.

T4 Endonuclease V
T4 Endonuclease V functions as part of a base excision repair pathway to recognize and remove cyclobutane pyrimidine dimers. The enzyme binds to UV-irradiated DNA and processively scans the DNA until a pyrimidine dimer is encountered.

Exonuclease III
Exonuclease III is a 3’-5’ exonuclease releasing 5’ mononucleotides from dsDNA and exhibits AP-specific endonuclease, 3’ phosphatase and RNAse H activities.

Restriction Endonuclease.
Recognition sequence:
5'-A^A G C T T-3'
3'-T T C G A^A-5'