Inhibitor Removal
Definition
Laboratory steps applied to degraded bone before PCR amplification. Collagen hydrolysis products, humic acids, and heavy metals in aged bone inhibit DNA polymerase. Strategies include organic extraction, solid-phase silica purification, and dialysis to remove inhibitors while retaining short DNA fragments.
- Field
- Forensic DNA from skeletal remains
- Applies to
- Degraded bone samples before PCR
- Common inhibitors
- Collagen hydrolysis products, humic acids, heavy metals
- Methods
- Organic extraction, silica purification, dialysis
Common questions
Why can't a lab just add more DNA polymerase to overcome inhibition?+
The inhibitors bind polymerase or chelate the magnesium the enzyme needs, so adding more enzyme does not restore activity. The inhibiting compounds have to be physically separated from the DNA before amplification will succeed.
What is the trade-off in choosing an inhibitor removal method for bone extracts?+
More aggressive purification removes inhibitors more completely but risks losing the already scarce, short DNA fragments typical of degraded bone, so labs balance purification stringency against DNA yield case by case.
Related terms
- Cortical Bone
- The dense outer shell of long bones, also called compact bone. Porosity is less than 10 percent. High mineral density, slow water...
- Hydroxyapatite
- The calcium phosphate mineral (Ca10(PO4)6(OH)2) that constitutes approximately 70 percent of bone dry weight. Its crystals bind to DNA fragments electrostatically, slowing...
- Osteon (Haversian System)
- The basic structural unit of compact cortical bone: a central Haversian canal surrounded by concentric lamellae of mineralised collagen. Osteon diameter and...
- Stable Isotope Analysis
- A technique that measures the ratio of stable (non-radioactive) isotopes of elements such as strontium, oxygen, and carbon in a biological sample....
- Trabecular Bone
- The spongy inner lattice of bone, found at epiphyses and in flat bones. Porosity of 50 to 90 percent allows rapid water...