OLIGONUCLEOTIDE SYNTHESIS    (Custom made Oligo's) For Oligo enquiries or to place an Order please use the form  here. Severn Biotech has been making oligonucleotides since 1990 and they are synthesised by experienced and dedicated chemists, who make quality the highest priority. Oligo's are made using standard Cyano-Ethyl-Phosphoramidite Chemistry on a solid phase to which a wide range of reporter molecules, base modifications and base substitutions are available,some of which are described here. Dabcyl, TAMRA, Fuourescein, Biotin,FAM,Amino-Link, 8-Oxo-Guanindine,Bromo-Uracil,etc. Oligonucleotides undergo UV analysis to assess the quantity of the product and to ensure the salt content has been eliminated by the desalting process which is standard procedure. Each oligonucleotide sequence is guaranteed to be correct and meet requisite QC specifications. Delivery is within two to three working days from receipt of order with an extra day added on if any modifications or purification is required. For large orders please enquire about delivery times.   Scale of Synthesis Quantity Required Synthesis can be performed at different scales normally 0.05M, 0.2M and 1.0M. Larger synthesis scales providing mg quantities necessary for in vivo work, are available upon request. Estimated Minimum yield of Oligonucleotide (for oligos of average base length 20)   Unpurified yield Purified yield   OD g OD g 0.05M 8 160 2 80 0.2M 23 800 5 300 1.0M 60 4000 45 1500 1 OD unit is taken to be equivalent to 20g DNA Oligo Purification All oligonucleotides synthesised by Severn Biotech are desalted as standard. Further purification is available via either HPLC, C18 cartridge or PAGE, the level of purification varying between these different techniques as outlined below: Purification method Typical purity HPLC 90-97% C18 cartridge 90-95% PAGE 99% RNA Synthesis RNA oligos are available at the 0.2M and 1.0M scales of synthesis. Standard length oligos (up to 20-mers) are generally synthesised, but longer oligonucleotides may be considered upon request. RNA molecules can either be supplied with or without a 2'-allyl protecting group. This protecting group greatly increases the stability of the RNA oligonucleotide during storage, but will need to be removed prior to use. Handling and Storage Oligonucleotides Storage of Oligonucleotides Oligonucleotides are delivered as a lyophilised pellet and should be kept in this form if long term storage is required. Shelf life if stored at -20° is over a year. Working solutions of DNA should not be kept longer than overnight to avoid degradation of the product. Only sterile water and buffer solutions should be used. If storing as a solution, concentrations should be mMolar i.e. stock solutions and should be aliquoted out before freezing as repeated freeze/thaw conditions may cause degradation of the oligo. If kept at -20°C storage is from three-six months. At 4° this is reduced to approximately two weeks. Determining the Molecular Weight of an Oligonucleotide Base MW -A- 312.2 -C- 288.2 -G- 328.2 -T- 303.2   Molecular Weight Determination The exact weight of an oligonucleotide (MWo) is as follows: MWo = [No. of As x MWA] + [No. of Cs x MWC] + [No. of Gs x MWG] + [No.of Ts x MWT] Approximate Conversion Factors 1.0 0D unit Wavelength 260nm ~ 20g DNA Approximate MWo = No. of bases x 310 Melting temperature (Tm) ~ [2°C x No. of As & Ts] + [4°C x No. of Gs & Cs] Further information For further details regarding Oligo synthesis delivery times purity data or price quotation please use our contact information above, with your sequence details and quantity requirments. We will immediately forward a quotation and contact you to discsuss your project.    For Oligo enquiries or to place an Order please use the form  here.