I wanted to talk a little about the selection characteristics of Agencourt’s AMPure beads, a bead-reagent combination that purifies PCR reactions.
INSTRUCTION MANUAL NEBNext. If using AMPure XP Beads, allow the beads to warm to room temperature for at least 30 minutes before use. These bead volumes may not work properly for a cleanup at a different step in the workflow, or if this is a second cleanup at this step. For cleanups of samples contained in different buffer conditions, the. Available, the Agencourt AMPure XP reagent system is a highly efficient, easily automated PCR purification system that delivers superior quality DNA with no salt or dNTP carryover. The AMPure XP reagent system uses an optimized buffer to selectively and reversibly bind PCR amplicons that are 100bp and larger to solid-phase paramagnetic beads.
This stuff is incredible in terms of simplicity, efficiency, and high-throughput compatibility. I have a sneaking suspicion that AMPure, not unlike fire to Prometheus, was handed down from the gods to benefit humanity. You just dunk it into your sample, slosh it around, stick it to a magnet, wash, wash again, and elute in your favorite buffer. No muss, no fuss.
We were wondering, though, about its selection process. What size fragments are selected by the AMPure beads, specifically at which ratio of beads to sample? So, like diligent scientists, we rolled up the sleeves of our labcoats and… read the protocol.
The protocol recommends washing your sample in a 1.8:1 ratio of beads to sample, although it says that fragments less than 100bp will be omitted at this ratio, it doesn’t say which sized fragments will be selected. We found this remarkably helpful technical bulletin, which describes calibrating each batch of AMPure beads with various ratios of DNA ladder.
So I did our very own calibration with AMPure beads using Fermentas’s GeneRuler™ Low Range DNA Ladder (25-700 bp). I added 30ul ladder to various concentrations of AMPure beads according to Agencourt’s instructions.
Ampure Xp Beads Manual
(Actually, if you’re looking for good AMPure instructions, I recommend looking at Illumina’s TruSeq™ Sample Preparation Guide. Honestly, their instructions are more comprehensive than Agencourt’s, and easier to read.) After purifying each sample, I bookended the various AMPure:ladder ratios with 10ul non-purified ladder on a 2% TBE gel for easy comparison.
Ampure Xp Beads Patent
Without any further ado, here are the results: