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Where is DNase

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Where is DNase

Postby joveryant » Fri Oct 13, 2006 6:39 am

hi everyone, I have a littile question:

Since DNase degrades DNA into ATP......

We won't place DNA in RT for too long.

What confused me is "where is DNase come from?!"
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Re: Where is DNase

Postby Dr.Stein » Sat Oct 14, 2006 3:49 am

joveryant wrote:Since DNase degrades DNA into ATP......

:shock: I don't think DNAse converts DNA into ATP... it is an enzyme to "open" the double-helix to facilitate transcription process :? This is not my major, I am blank :oops:
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Postby joveryant » Sun Oct 15, 2006 11:05 pm

Hi Keef! thank you :lol:
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Postby dipjyoti » Mon Oct 16, 2006 8:14 am

DNase I is a versatile enzyme that nonspecifically cleaves DNA to release 5'-phosphorylated di-, tri-, and oligonucleotide products (1). A powerful research tool for DNA manipulations, DNase I is used in a range of molecular biology applications. Some of its uses include:

degradation of contaminating DNA after RNA isolation,
"clean-up" of RNA prior to RT-PCR and after in vitro transcription,
identification of protein binding sequences on DNA (DNase I footprinting),
prevention of clumping when handling cultured cells, and
creation of a fragmented library of DNA sequences for in vitro recombination reactions.
While frequently used in the laboratory, the activity of DNase I is still a mystery to many researchers. Are the "units" of one source of DNase I the same as that of another? Are calcium and magnesium ions required for activity? Will DNase I degrade DNA in DNA:RNA hybrids? Can DNase I remove 100% of DNA contamination from RNA preparations? In this article we will try to answer some of the questions surrounding this commonly used enzyme.

Better Unit Definition

The specific activity of a given DNase I preparation reflects the potency of the enzyme per unit mass in degrading double-stranded DNA (dsDNA). Historically, this activity has been expressed in Kunitz units (2), where 1 Kunitz unit is the amount of DNase I added to 1 mg/ml salmon sperm DNA that causes an increase of 0.001 absorbance units per min when assayed in a 0.1 M NaOAc (pH 5.0) buffer. This buffer, however, is not representative of the conditions that are typical for DNase I digestions (see "Treating RNA Samples with DNase I" at right). Consequently, Ambion offers DNase I with a unit designation that better reflects how well the enzyme will degrade DNA under standard conditions. Updated procedures measure DNase I activity using real-time fluorescence assays which allows for fast, quantitative measurements.

For further info see http://www.sigmaaldrich.com/Area_of_Int ... ase_I.html

Dip Jyoti Chakraborty
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