Tryptophan
Tryptophan — An essential aromatic amino acid (Trp, W) with an indole side chain. The primary contributor to protein UV absorption at 280nm.
What Is Tryptophan?
Tryptophan (Trp, W) is the largest and rarest amino acid, containing an indole aromatic ring system (MW: 204.23 Da). It is essential for intrinsic fluorescence measurements (excitation 280 nm, emission 340 nm), making it a natural built-in probe for peptide binding and folding studies.
Key Properties
- Fluorescence: Trp emission wavelength shifts from 350 nm (solvent-exposed) to 320 nm (buried/hydrophobic), reporting on local environment
- UV absorbance: Primary contributor to peptide absorbance at 280 nm (ε = 5,500 M⁻¹cm⁻¹), enabling concentration determination
- Oxidation-sensitive: Forms kynurenine, hydroxytryptophan, and other products upon oxidation
- Receptor interactions: Trp residues in substance P, hexarelin, and NPY make critical receptor contacts
Frequently Asked Questions
What is Tryptophan?
An essential aromatic amino acid (Trp, W) with an indole side chain. The primary contributor to protein UV absorption at 280nm.
Why is Tryptophan important in peptide research?
Tryptophan is a fundamental concept in amino acid as it relates to peptide science. It directly influences experimental design, compound characterization, and the reliability of research outcomes across biochemistry and molecular biology disciplines.