Ribonucleic+acid,+transfer+from+baker's+yeast+Sigma

Sigma tRNA carrier molecule

http://www.sigmaaldrich.com/catalog/ProductDetail.do?lang=en&N4=R5636|SIGMA&N5=SEARCH_CONCAT_PNO|BRAND_KEY&F=SPEC


 * CAS Number: [|9014-25-9]
 * MDL number: [|MFCD00132200]
 * Product Number: R8759

I ordered the lyophylized powder, but I should have ordered the buffered aqueous solution (product number[| R5636])

Invitrogen also sells tRNA @http://www.ambion.com/catalog/ProdGrp.html?fkProdGrp=139

Here are some reconstitution Instructions (from an e-mail from Sigma on 9-28-11) A solution with OD of 1 = approximately 40 ug single-stranded DNA or RNA, 50 ug double-stranded DNA. For RNA, the ratio of A260/A280 should be 2. If the ratio is higher or lower, the sample has contaminating DNA or protein. Transfer Ribonucleic Acid should be stable in solution for at least six months frozen in 10 mM Tris buffer, pH 7-8 at 10 mg/ml.

For the precipitation protocol they recommended this link: http://uregina.ca/~ngdann/Bioc422/proj1.htm
 * excerpt: Alternatively, nanogram quantities of nucleic acid can be efficiently precipitated by adding yeast tRNA carrier to the solution to obtain a nucleic acid concentration of 10 @g/mL before initiating the extraction and precipitation procedure.
 * nucleic acids remain in the aqueous phase

The Molecular Cloning Books also have some useful information about tRNA
 * Carrier RNA (1 mg/mL)
 * Prepare a stock of carrier RNA by dissolving commercially available yeast tRNA at a concentration of 10 mg/mL in sterile TE (pH 7.6) containing 0.1 M NaCl. Extract the solution twice with phenol (equilibrated in Tris-Cl [pH 7.6]) and twice with chloroform (nucleic acids will be in aqueous phase). Recover RNA by precipitation with 2.5 volume volumes of ethanol at room temperature. Dissolve the precipitated RNA at a concentration of 10 mg/mL in sterile TE (pH 7.6) divide the stock into small aliquots, and then store them at -20 C

JC found this useful link for preparing DNA for electroporation. It has a nice protocol on precipitating using tRNA. http://userpages.umbc.edu/~jwolf/m7.htm

Working concentration of tRNA carrier for use in ligation
 * 10-20 ug/mL Yeast tRNA (according to A8.13 of Molecular Cloning Book)
 * 10 ug/(20 uL ligation reaction) according to http://userpages.umbc.edu/~jwolf/m7.htm

Disadvantages of tRNA Advantages of tRNA
 * can't be used for precipitating nucleic acids that will be used as substrates in reactions catalyzed by polynucleotide kinase or terminal transferase since the termini of yeast RNA are excellent substrates for these enzymes and would compete with the termini contributed by the target nucleic acid
 * It doesn't interfere with interactions between DNA and proteins like glycogen would