# Luckau Protocols:PrimerResuspension

 Primer Resuspension

## Purpose

Primers are used in polymerase chain reaction (PCR) to amplify a targeted region of genomic DNA. When ordered, primers arrive dry (in crystalized form), so, before use, the primer must be resuspended in liquid. In the Clark Lab, we resuspend primers to a concentration of 20µM (both unlabeled and labeled).

## Materials

• dry primer (we currently use LifeTech: Invitrogen and AppliedBiosystems)
• each primer will be synthesized at a given amount of moles, usually in nanomoles (nmol) or picomoles (pmol) - find this information on the data sheets supplied by the primer manufacturer
• Low TE (pH 8.0)

## Protocol

### Calculations

• Want: 20µM primer

• $\tfrac{ \mbox{(number of nmol)}}{x \mbox{ } \mu \mbox{L Low TE}} = \mbox{20} \mu \mbox{M}$

$x \mbox{ } \mu \mbox{L Low TE} = \tfrac{ \mbox{(number of nmol)}}{\mbox{20} \mu \mbox{M}}$

note that: $\mu \mbox{M} = \tfrac{\mbox{pmol}}{\mu \mbox{L}} \bullet \tfrac{\mbox{nmol}}{1000 \mbox{ pmol}}$

$x \mbox{ } \mu \mbox{L Low TE} = \tfrac{ \mbox{(number of nmol)} \mbox{ (}1000 \mbox{ } \mu \mbox{L)}}{\mbox{20 nmol}}$

$x \mbox{ } \mu \mbox{L Low TE} = \mbox{(number of nmol)} \bullet 200$

### Resuspend!

1. spin down primer tube to ensure all primer crystals are at the bottom of the tube
2. add Low TE, pH 8.0 (as calculated, see above)
3. On the tube, write the concentration (20µM), then initial and date it
4. let tube sit overnight in fridge (4°C) to allow the crystals to fully dissolve into the buffer
5. store in fridge (4°C)