Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Analysis of protein data bank information about the coordinates of definite atoms of protein macromolecules provides an opportunity to evaluate the efficiency of non-radiative resonance energy transfer within the model of fixed, strictly oriented oscillators. Such evaluations for trypsin and trypsinogen (and also for trypsin complex with a pancreatic inhibitor) show that the efficiency of energy transfer among each pair of tryptophan residues is negligibly small. It is also shown that a fairly effective energy transfer from tyrosine to tryptophan residues is possible. The conclusions have been made that the Tyr-Trp energy transfer is one of the factors determining the shape of the trypsin polarization spectrum, and that upon fluorescence excitation at the long-wavelength edge of the absorption spectrum, the depolarization of trypsin fluorescence in aqueous solution at ambient temperature - compared to model compounds (tryptophan, N-acetyltryptophan, glycyltryptophan, etc.), under the conditions of infinite viscosity - is due to the Brownian rotational motion of the macromolecules as a whole as well as the intramolecular mobility. The differences in the level and character of intramolecular mobility of trypsin and trypsinogen are discussed.
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PMID:What causes the depolarization of trypsin and trypsinogen fluorescence. Intramolecular mobility or non-radiative energy transfer? 382 70

It is found that for nearly all the proteins under study, the value of 1/P0', cut off on the ordinate by the extrapolation of the dependencies 1/P = f(T/eta . /tau B), is larger than the value of 1/P0 for model compounds--tryptophan, N-acetyltryptophan, glycyl-tryptophan. It is shown, that this may indicate the existence both of high-frequence intramolecular mobility, with the relaxation time rho much less than tau, and low-frequency intramolecular mobility the magnitude rho of which is of the same order as tau, independent on the medium viscosity. This peculiarity in the interpretation of the data, received by the method of rotational depolarization of UV-fluorescence of proteins arises because some tryptophan residues within the macromolecules of proteins are not accessible to the molecules of the solvent and that is why the rotational relaxation time of their intramolecular mobility is not dependent on the viscosity of the solvent. It is indicated that intramolecular mobility is inherent in tryptophan residues both with short wave and long wave spectrum of UV-fluorescence. The relaxation time, measured by the method of fluorescence depolarization, appeared to be smaller than that calculated for the short axe of an equivalent ellipsoid of revolution for a series of proteins (lysozyme, trypsin, pepsin, bovin serum albumin in acid medium, myelin basic protein). This indicates the existence of intramolecular mobility the magnitude rho of which is of the same order as tau dependent on the solvent viscosity in these proteins. Zymogens--trypsinogen and pepsinogen do not have such intramolecular mobilities.
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PMID:[Polarization of intrinsic fluorescence of proteins. III. Intramolecular submobility of tryptophan residues]. 662 23