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Published on: December 15, 2017
Photophysical properties of ricin
A K Gaigalas1, K D Cole, S Bykadi
1Biochemical Science Division, National Institute of Standards and Technology, Gaithersburg, MD, USA. Adolfas.gaigalas@nist.gov
Photochemistry and Photobiology
|September 21, 2007
Summary
This study quantifies ricin
Area of Science:
- Biochemistry
- Molecular Biophysics
Background:
- Ricin is a toxic protein with significant implications in toxicology and medicine.
- Understanding the photophysical properties of ricin is crucial for developing detection and characterization methods.
Purpose of the Study:
- To determine the molar absorption coefficient and spectral properties of ricin.
- To elucidate the contribution of tryptophan and tyrosine residues to ricin's absorption spectrum.
- To investigate energy transfer mechanisms and structural coupling within ricin.
Main Methods:
- Spectrophotometry to measure molar absorption coefficient at 279 nm.
- Amino acid analysis for ricin concentration determination.
- Analysis of absorption and fluorescence spectra to assess residue contributions and energy transfer.
- Structural analysis to determine tryptophan residue coupling.
Main Results:
- Molar absorption coefficient of ricin determined to be (93,900+/-3300) L mol(-1) cm(-1).
- Absorption spectrum primarily attributed to tryptophan (69%) and tyrosine (31%) residues.
- Evidence of energy transfer from tyrosine to tryptophan residues.
- Ricin undergoes irreversible thermal unfolding between 65-70°C.
Conclusions:
- The photophysical properties of ricin are well-characterized, with significant contributions from aromatic amino acids.
- Tryptophan residues play a dominant role in ricin's spectral characteristics and exhibit internal coupling.
- Ricin's denaturation and unfolding behavior provide insights into its structural stability.
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