Amino Acid Racemisation
Definition
The conversion of biologically produced L-amino acids to D-amino acids over time at a temperature-dependent rate. The D/L ratio of aspartic acid in fingerprint eccrine residue is one candidate molecular clock for age-of-fingerprint estimation.
- Process
- L-amino acid converts to D-form over time
- Rate dependency
- Temperature-dependent
- Target amino acid
- Aspartic acid
- Application
- Fingerprint age estimation
Common questions
Why is racemisation described as a molecular clock?+
Because the L-to-D conversion proceeds at a roughly predictable rate once biological synthesis stops, measuring how far the ratio has shifted toward the D-form gives an estimate of elapsed time since deposition, in the same way radioactive decay rates are used to date other materials.
What limits the reliability of using this ratio to date a fingerprint?+
The conversion rate is sensitive to temperature and humidity history, which is rarely known precisely for a real scene, so the method currently gives a rough time window rather than a precise deposition time and remains an active research area rather than a routine casework tool.
Related terms
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- ACE-V
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- Blind Verification
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- MALDI-MSI
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- Micro-Computed Tomography (Micro-CT)
- High-resolution X-ray tomography producing volumetric 3D images. Used experimentally to recover latent fingerprints from curved laboratory exhibits without destructive development.
- NIST Latent Quality Metric
- A convolutional neural network-based quality scoring tool developed by NIST that assigns a quality score to latent fingerprint images in ANSI/NIST ITL...
- Squalene
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- Structured-Light Projection
- A 3D imaging method in which a known grid pattern of light is projected onto a surface; the distortion of the pattern...
- ULTR (Uniform Language for Testimony and Reports)
- US Department of Justice standards restricting the language fingerprint examiners may use in court testimony and reports, prohibiting certainty claims not supported...