Fluorescence studies of the calcium binding to whiting (Gadus merlangus) parvalbumin.

The calcium binding by parvalbumin of whiting (Gadus merlangus) has been studied using tryptophanyl fluorescence characteristics. Titration of Ca2+-free parvalbumin with Ca2+ leads to a very pronounced blue shift, narrowing and intensification of the fluorescence spectrum. These spectral changs proceed in two stages reflecting the existence of at least three forms which can be interpreted as (a) the protein without Ca2+, (b) with one Ca2+ and (c) with two bound Ca2+ ions/molecule.

Small differences in tryptophan fluorescence spectra of 'sodium' and 'potassium' forms of (Na+, K+)-dependent adenosinetriphosphatase.

A detailed comparative analysis of tryptophan fluorescence spectra of 'sodium' and 'potassium' forms of (Na+, K+)-activated ATPase was carried out. The 'potassium' form spectrum is shifted relative to that of the 'sodium' form by approximately 0.5-1 nm towards shorter wavelengths.

Lack of gross protein structure changes in the working cycle of (Na+, K+)-dependent adenosinetriphosphatase. Evidence from infrared and intrinsic fluorescence spectroscopy data.

Infrared and tryptophan fluorescence spectra of practically all sufficiently stable functional complexes of a highly purified preparation of membrane-bound (Na+, K+)-dependent ATPase have been measured. The formation of any functional complex was not accompanied by any considerable change of either shape or position of the tryptophan fluorescence spectrum. Only in the presence of adenine nucleotides was there a small decrease of fluorescence intensity (by 5-8%), which apparently results from a change of the sample light scattering.

Relationship of thermal quenching of protein fluorescence to intramolecular structural mobility.

Temperature dependence (over the range from 5 to 75 degrees C) of the fluorescence quantum yield--the parameter sensitive to the rapid (ns) mobility--has been investigated. For native proteins containing 1--2 fluorescing chromophores this dependence in the non-denaturing temperature range can be described by the equation 1/q = a + b . T/eta (a and b are temperature-independent constants, T is the temperature (K), eta is the viscosity of water, (cP).

Resonant internal-reflection prism spectroscopy using surface, guided, and Fabry-Perot EM waves.

The resonant EM modes of three media prism configurations and their use as EM probes of surfaces, interfaces, and thin films are discussed. The excitation of surface EM, guided EM, and Fabry-Perot EM modes using resonant internal reflection (RIR) in the prism is shown to provide a powerful spectroscopic tool for obtaining information about the optical constants of surfaces and thin overlayers. The main advantages of using resonant modes as EM probes are the sizable buildup of EM fields at the surface that occurs at resonance and the fact that the resonant excitation involves the matching of wavevector as well as of frequency.

The fine structure of luminescence spectra of azurin.

The spectra of azurin absorption, fluorescence, phosphorescence and fluorescence excitation have been measured in aqueous solutions at ordinary and liquid nitrogen temperatures. The fluorescence spectra of azurin even at ordinary temperatures have a well resolved fine vibrational structure. The frequency analysis reveals practically the same wave number distances between the main structure peaks in fluorescence spectra at room and low temperatures and in phosphorescence spectra.

Reinterpretation of luminiscence properties of neurotoxins from the venom of Middle-Asian corba Naja oxiana eichw.

A new interpretation of previous work (Bukolova-Orlova, T. G., Burstein, E.

Investigation of some physico-chemical properties of muscular parvalbumins by means of the luminescence of their phenylalanyl residues.

The influence of pH, temperature and Ca2+-release on the phenylalanyl and tyrosyl fluorescene of muscular parvalbumins from white muscles of hake and carp has been investigated. Within the pH range from 7 to 8, Ca2+-saturated parvalbumins show a conformational change registered by fluorescence, that is associated with the release of some of the bound Ca2+. Removal of Ca2+ by means of EGTA (ethyleneglycolbis-(aminoethylether)tetra-acetic acid) considerably narrows the region of protein nativity, increases the accessibility of their chromophores to quencher ions (Cs+ and CNS-) and decreases their stability against heat denaturation.