Chaotropic Salt
Definition
Guanidinium thiocyanate or hydrochloride at 4-6 M concentration. Disrupts the hydration shell of DNA and causes it to bind electrostatically to silica surfaces. Forms the basis of silica-column and magnetic-bead extraction.
- Common examples
- Guanidinium thiocyanate, guanidinium hydrochloride
- Working concentration
- 4-6 M
- Mechanism
- Disrupts DNA hydration shell
- Application
- Silica-column and magnetic-bead extraction
Common questions
Why does disrupting the hydration shell help extract DNA?+
Water molecules normally shield DNA's charged phosphate backbone; removing that shell exposes the backbone so it can bind electrostatically to silica surfaces, which is the physical basis of solid-phase extraction methods.
Why are chaotropic salts also useful beyond DNA binding?+
At the same time they denature proteins and inactivate nucleases, which protects the DNA from degradation during the lysis step and is part of why they are included early in most silica-based extraction protocols.
Related terms
- Chelex-100
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- Inhibition Index
- A quantitative measure of PCR inhibitor burden in a DNA extract, derived from the Ct shift of an internal positive control (IPC)...
- Maxwell RSC 48
- Promega cartridge-based magnetic-bead extraction instrument. Each cartridge is pre-loaded with all reagents; closed-format processing eliminates cross-contamination. Used at FBI Laboratory and AFMES.
- Phenol-Chloroform-Isoamyl Alcohol (PCI) Extraction
- Organic extraction method using differential solubility to partition DNA into an aqueous phase while proteins and lipids accumulate at the organic-aqueous interface...
- QIAcube Connect
- QIAGEN robotic workstation that automates spin-column extraction protocols (QIAamp DNA Investigator). Processes 12 samples per 60-minute run; used in UK, US and...