Tryptophan spectroscopy

Measuring Protein Sta.bihty, Protein stabihty is usually measured quantitatively as the difference in free energy between the folded and unfolded states of the protein. These states are most commonly measured using spectroscopic techniques, such as circular dichroic spectroscopy, fluorescence (generally tryptophan fluorescence) spectroscopy, nmr spectroscopy, and absorbance spectroscopy (10). For most monomeric proteins, the two-state model of protein folding can be invoked. This model states that under equihbrium conditions, the vast majority of the protein molecules in a solution exist in either the folded (native) or unfolded (denatured) state. Any kinetic intermediates that might exist on the pathway between folded and unfolded states do not accumulate to any significant extent under equihbrium conditions (39). In other words, under any set of solution conditions, at equihbrium the entire population of protein molecules can be accounted for by the mole fraction of denatured protein, and the mole fraction of native protein,, ie. 

Fluorescence spectroscopy offers several inherent advantages for the characterization of molecular interactions and reactions. First, it is 100-1000 times more sensitive than spectrophotometric techniques. Second, fluorescent compounds are extremely sensitive to their environment. Tryptophan residues that are buried in the hydrophobic interior of a... 

Nishio, J., Yonetani, I., Iwamoto, E., Tokura, S.,Tagahara, K., and Sugiura, M., Interaction of caffeine with 1-tryptophan study of 1H nuclear magnetic resonance spectroscopy, J. Pharm. Sci., 79,14,1990. 

Pierce DW, Boxer SG (1995) Stark effect spectroscopy of tryptophan. Biophys J 68 1583-1591... 

Enzyme structure may be studied by fluorescence spectroscopy [238-244]. Excitation in the 280-310 nm absorption bands of proteins, usually results in fluorescence from tryptophan (Trp) residues in the 310-390 nm region. The fluorescence from the Trp residues is a convenient marker for protein denaturation and large decreases or red-shifts in fluorescence are observed when proteins are denatured. These changes are most often due to the exposure of the Trp residues that are buried in the protein and may be due to the changes in the proximities of specific residues that may act as fluorescence quenchers. Fluorescence emission characterization of the immobilized... 

ROS can modify amino acid side chains, with histidine, tryptophan, cysteine, proline, arginine, and lysine among those most susceptible to attack (Brown and Kelly 1994). As a result, carbonyl groups are generated, and these carbonyl concentrations can be measured directly in plasma by using atomic absorption spectroscopy, fluorescence spectroscopy, or HPLC following reaction with 2,4-dinitrophenylhydrazine. 

In using the method of the red-edge shift in UV fluorescence spectroscopy, we should take into account the possibility of emission not only of tryptophan but also of tyrosine residues. In many tryptophan-containing proteins, tyrosine fluorescence is not observed. However, it is considerable in serum albumin, and the decrease in its intensity is responsible for the long-wavelength shift of the spectra recorded at Aex < 290 nm. At Aex > 292 nm, the tyrosine component should be completely absent. 

A. P. Demchenko, Red-edge-excitation spectroscopy of single-tryptophan proteins, Eur. Biophys. J. 16, 121-129 (1988). 

It is now clear that in the absence of molecular oxygen most proteins phosphoresce in aqueous solutions at ambient temperature.(10) In this chapter we discuss the use of phosphorescence of tryptophan to study proteins, with emphasis on measurements at room temperature. Comparisons between phosphorescence and the more commonly used fluorescence spectroscopy are made. Comprehensive reviews of protein luminescence have been written by Longworth.(n 12 1 A discussion on the use of phosphorescence at room temperature for the study of biological materials was given by Horie and Vanderkooi.(13)... 

M. Nakanishi, M. Kobayashi, M. Tsuboi, C. Takasaki, and N. Tamiya, Electronic spectroscopy and deuteration kinetics of tyrosine and tryptophan residues An application to the study of erabutoxin b. Biochemistry 19, 3204-3208 (1980). 

Helical heptad repeat sequences have been reported to be well behaved although they are difficult to characterize by NMR spectroscopy due to spectral overlap. The motifs that have been shown to have native-like properties, and are not highly repetitive, have cores composed of aromatic amino acid side chains of, for example, phenylalanine and tryptophan. In four-helix bundle motifs [1, 2], the /1/la-motif BBAl [5] and the /1-sheet protein Betanova [9], the formation of the folded structure appears to be strongly dependent on such residues although the energetics have not been calculated by substitution studies. As a tentative rule, therefore, the probability of success in the design of a new protein is probably much higher if residues are included that can form aromatic clusters in the core (Fig. 5). 

This enzyme [EC 1.4.99.3], also known as amine dehydrogenase and primary-amine dehydrogenase, catalyzes the reaction of R-CH2-NH2 with water and an acceptor to produce R-CHO, ammonia, and the reduced acceptor. Tryptophan tryptophylquinone (TTQ) is the cofactor for this enzyme. See Resonance Raman Spectroscopy Topaquinone... 

In 1990, Nakamura et al. reported for the first time the complete biosynthetic origin of the whole carbon skeleton of carbazomycin B isolated from lower plants (378). Based on feeding experiments with and C-labeled compounds, followed by measurement of radioactivity and C-NMR spectroscopy, it was shown that L-tryptophan (408) contributes to C-3 and C-4 of the hexasubstituted aromatic ring, in addition to the indole ring, indicating tryptophan as the progenitor of carbazomycin B (261), in contrast to Chakraborty s proposal of 2-methylcarbazole. The indole part of L-tryptophan (408) is formed by incorporation of two carbons from phosphor-ibosyl diphosphate (430), with loss of the anthraniiic acid (397) carboxyl. The... 

In a recent study, Fernandez-Bertran et al. used mechanochemical reactions to prepare a number of hemin complexes with amino acids such as arginine, histidine, lysine, methionine and tryptophan. The basic amino acids react with the hemin peripheral propionic acid groups, while arginine is also able to form a pentacoordinated complex at the Fe(III) centre. The reactions were followed by IR and Mossbauer spectroscopies [77a]. The solid-state reaction of hemin with KCN, Na2S and various substituted imidazoles has also been investigated [77b]. 

UV-Visible Absorption Spectrum Absorption spectroscopy Tyrosine-Tryptophan environments, presence of absorbing ligands or impurities. ... 

Fluorescence Spectrum Fluorescence spectroscopy Tryptophan environment, presence of fluorescent ligands or impurities.b... 

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