What are Value Oligos?

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Answer

Value Oligos are the most cost-effective and fastest way to order oligos. They are available for 5-40-mers, at a 25 or 50 nanomole scale, with a range of purification options to suit your needs, and are eligible for next-day delivery. The cost is calculated per oligo as opposed to per base. Value Oligos are not available with modifications. Value Oligos undergo the same QC standards as our standard oligos with the same manufacturing process.

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f385c0b74f857b05ec3dc001754715a0_FAQ

Why are HPLC or cartridge purification not offered for larger oligos?

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Answer

As oligos increase in length, the column purification is less effective in separating the failure oligos from the correct products. PAGE purification would be the method of choice in this case.

Answer Id: E7283

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f82f3640341373a1bcc435fa5af10177_FAQ

Why do different programs calculate different Tm values?

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Answer

Tm values are not absolute - they are an approximation of the melting temperature range which exists. A thermal profile for a given oligo shows a 10-15 degree range of melting depending on the amount of salt but also on the base composition and concentration of primer in the reaction which are not precisely defined. One should not rely solely on the given Tm value as the only one that will work. Tm is the temperature at which 50% of the primer and its complementary sequence are present in a duplex DNA molecule. The Tm is necessary to establish an annealing temperature for PCR. Reasonable annealing temperatures range from 55 degrees C to 70 degrees C. Annealing temperatures are generally about 5 degrees C below the Tm of the primers. Since most formulas provide an estimated Tm value, the annealing temperature is only a starting point. Specificity for PCR can be increased by analyzing several reactions with increasingly higher annealing temperatures.

Answer Id: E7284

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33192df7e496cf6ce083da7618c5e8c8_FAQ

How many oligos do I need to order for a 96-well plate order or a 384-well plate order?

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Answer

The plate orders must contain an average of 24 or more oligos per plate for 96-well plates or 192 or more oligos per plate for 384-well plates across the entire order.

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523853e2a9bf738b40b9eb9a30db9ad5_FAQ

How are these oligos quality controlled?

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Answer

For 25, 50, and 200 nmol desalted and cartridge-purified DNA oligos, there is 100% A260 analysis. Random samples of 25% of the oligos produced are tested by either capillary electrophoresis or mass spectrometry. DNA oligos that are desalted and ordered at 25 and 50 nmol scales also have 100% real-time digital trityl monitoring during analysis. Desalted DNA oligos ordered at 1 and 10 μmols, DNA oligos at any scale that are purified by HPLC and PAGE, the majority of the DNA oligos with 3’ and/or 5’ modifications, and RNA oligos have 100% A260 analysis and capillary electrophoresis or mass spectrometry.

Answer Id: E7286

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245ffeea19cbc9978668e2dfaa3acc21_FAQ

If I choose mixed bases, e.g., GC, for my oligo manufacturing, will it be a 50/50 mix?

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Answer

No, we do not guarantee 50/50 of mixed bases. If a mix of GC bases is requested, for example, the synthesizer would deliver half the normal amount of G and half the normal amount of C. Coupling efficiency is not taken into account. Therefore, it is possible that a mix, such as 30/70, will be delivered.

Answer Id: E7287

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1bfd94f280207e39ea782f8a7f5fe0df_FAQ

I’m seeing smearing after PCR. What is causing this?

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Answer

Please see some reasons below for seeing smearing:

-The enzyme, primer, Mg2+, and/or dNTP concentration was too high.
-The annealing temperature was too low for the primers being used.
-Too many cycles were used.
-The annealing and extension times were too long.
-Bad or old primers.
-Too much template was used initially, try to start with 104-106 molecules
-Consider using additives or PCR Optimizer™ Kit (Cat. No. K122001), especially if you feel strongly that the primers should work/have worked before and are using Taq.

Answer Id: E7288

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799e00aa98ea5a6672689f05e62416dd_FAQ

I’m getting low yield of my desired fragment. What am I doing wrong and how can I increase my yield?

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Answer

Please see our suggestions below to increase yield:

-Do not use a wooden toothpick to pick colonies or scoop out DNA from a gel prior to PCR. It has been reported that this technique can inhibit PCR. [Lee (1995) BioTechniques 18:225].
-Not enough enzyme was used.
-Denaturation/extension temperature was too high and enzyme died prematurely.
-Too much DMSO (>10%).
-Incorrect annealing temperature: run a series of reactions using different annealing temperatures, starting 5 degrees below the calculated Tm.
-Too few cycles.
-Insufficient or too much Mg2+.
-Poorly designed primers: double check primer sequence against template sequence, primers should have similar melting temperatures, avoid complementary sequences at the 3’ end of primers.
-Carryover inhibitors (e.g., blood, serum).
-Denaturation time was too short. Genomic and viral DNA can require denaturation times of 10 minutes.
-Not a long enough extension time was used depending on the size of product being amplified.
-Use of super-irradiated (treated with >2500 mj/cm2) mineral oil will either inhibit or decrease yield of PCR product [Dohner (1995) Biotechniques 18:964].
-Template had long runs of GC's [Woodford et al. (1995) Nucleic Acids Res 23:539 show that by eliminating all potassium from the amplification reactions, GC-rich regions in templates are sufficiently destabilized to allow PCR]. Alternatively, a combination of 1.0 M betaine with 6-8% DMSO or 5% DMSO with 1.2-1.8 M betaine can be used to amplify GC-rich templates [Baskaran (1996) Genome Res 6:633].
-Other inhibitors of Taq DNA polymerase were present (e.g., indigo dyes, heme, melanin, etc.). Add BSA to the PCR (~160-600 μg/mL), increase the amount of Taq, and/or increase the volume of the PCR to dilute out the inhibitor. The concentration of BSA to add may be dependent on the amount and type of inhibitor present. Additionally, fatty acid-free, alcohol-precipitated BSA, or Fraction V BSA all should be effective.

Answer Id: E7289

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fbc850f92dd2fb51e579ecde938942f0_FAQ

I’m getting no bands from my PCR product. What could cause this?

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Answer

Here are some reasons why your PCR experiment may be failing:

-NaCl at 50 mM will inhibit the enzyme.
-Too much KCl in the reaction. Do not exceed 50 mM.
-Incorrect annealing temperature was used.
-Incomplete denaturation (time and temperature must be long and high enough).
-Template had long runs of GC's [Woodford et al. (1995) Nucleic Acids Res 23:539 show that by eliminating all potassium from the amplification reactions, GC-rich regions in templates are sufficiently destabilized to allow PCR].
-10% DMSO partially inhibits Taq.
-Hemin (in blood samples) inhibits Taq.
-Use of super-irradiated (treated with >2500 mJ/cm2) mineral oil will either inhibit or decrease yield of PCR product [Dohner (1995) Biotechniques 18:964].
-Do not use a wooden toothpick to pick colonies or scoop out DNA from a gel prior to PCR. It has been reported that this technique can inhibit PCR [Lee (1995) BioTechniques 18:225].
-Other inhibitors of Taq DNA polymerase were present (e.g., indigo dyes, heme). Add BSA to the PCR, increase the amount of Taq, and/or increase the volume of the PCR to dilute out them inhibitor.

Answer Id: E7290

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d2e11a4bbd54bfddd44611e3a6a81518_FAQ

I’m getting an unexpected product when performing PCR. What could be the cause of this and what do you suggest I try?

Product FAQ

Answer

Please see the following possibilities and suggestions we have:

-Primer design: try longer primers to avoid binding at alternative sites, avoid 3 consecutive G or C nucleotides at the 3’ end.
-Annealing temperature: increase annealing temperature to increase specificity.
-Mg2+ concentration: try a lower concentration.
-DNA contamination: use aerosol tips and separate work area to avoid contamination, use UNG/UDG technique to prevent carryover.

Answer Id: E7291

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ae0d97e847df896ca90806eff2f0147b_FAQ

I’m seeing high molecular weight EtBr stainable material left in wells. Why is this happening?

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Answer

This artifact occurs when either too many cycles were performed or too much DNA is added to the reaction. Try heating to 65 degrees C and putting sample on ice before loading.

Answer Id: E7292

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e4f40a1c304c83f3110acc2eaa261b25_FAQ

I received my primer order, but the yield is lower than the scale that I ordered. Why is this?

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Answer

The scale that is ordered refers to the starting synthesis scale, or amount of starting material used to create your oligo. Based on purification and efficiency, you will receive less than the starting synthesis scale. However, we do have a minimum yield guarantee based on the starting synthesis scale which can be found here: https://www.lifetechnologies.com/us/en/home/products-and-services/product-types/primers-oligos-nucleotides/invitrogen-custom-dna-oligos/oligo-ordering-details/oligo-minimum-yield-guarantee.html.

Answer Id: E7293

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31f0370052f798324596bd2ee558cdb1_FAQ

I’m getting low yield of my oligo upon reconstitution. What happened?

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Answer

The oligo may not have been fully solubilized. After addition of TE buffer, make sure the oligo was vortexed for a full 30 seconds and/or pipette up and down more than 10 times. Primers may be present along the sides of the tubs, so when resuspending the oligo, the sides of the tubes should be “rinsed” too.

Answer Id: E7294

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76b3305be84782cc5852c019757c0382_FAQ

I ordered a primer with restriction enzyme sites flanking the 3’ and 5’ ends of my oligo with desalted purification. When trying to subclone the PCR product, I get very few colonies. I have tested all conditions, and it seems to be the oligo causing the problem. Can you explain why this happened?

Product FAQ

Answer

Better purification of the oligos is recommended to provide you with full-length oligo sequence. Adding restriction sites adds on 10 or more bases to the basic 20-25-mer, making primers longer than 30 bases with a relatively low percentage of full-length sequences after desalting. Additionally, failure sequences occur at the 5’ end of the sequence as oligos are generated from 3’ to 5’ end. Therefore, restriction sites introduced at the 5’ end of primers can be compromised, resulting in missing bases.

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59d47d44b31148aeb225418a3b31ca7a_FAQ

I’m missing a nucleotide in the middle of my sequence. How could this happen?

Product FAQ

Answer

There are two possibilities that could occur in any round of extension when creating your primer:

1.The added base is not detritylated correctly, missing one base addition but allowing possible extension in the next round.
2.The trityl group was removed, but not coupled or capped correctly before addition of the next base, allowing the chain to continue.

Answer Id: E7296

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ff7713e6113e25aa3655808616b408b8_FAQ