ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
A new optical method intended for interfacial protein studies has surfaced from the observation of near UV second harmonic generation (SHG) from the aromatic amino acids. Here, the first hyperpolarizability, β=4.72±0.52×10−30 esu, of t-butyloxycarbonyl-L-tryptophan is measured for SHG at 266 nm, and its polar orientation at the air–water interface is deduced. The indole ring nitrogen atom is found to point upwards at the interface. From a monolayer surface density of 1.74±0.15 adsorbate molecules/nm2, it is estimated that a minimum of 0.49 Trp residues/nm2 of surface area can be detected above the water background for this wavelength. SHG studies of tryptophan-containing peptides and proteins based on these results have the potential to complement existing linear optical techniques by providing new information on interfacial molecular ordering. © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.470247
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