Instant success for Instant Pharmacology

Instant Pharmacology (1999). Saeb-Parsy K, Assomull RG, Kahn FZ, Saeb-Parsy K, and Kelly E. John Wiley and Sons 349 pp. £19.99 pbk; ISBN 0471976393 © 1999 John Wiley & Sons, Inc.     

Increase of accessibility of murine lens protein fluorophores to water in the development of radiation-induced cataract

The accessibility of tryptophanyl fluorophores in crystalline proteins to water molecules was estimated by measuring the enhancement of the fluorescence of lens homogenates in 70% D2O as compared to 100% H2O. Assuming that two sorts of fluorophores exist in the proteins, one entirely accessible to H2O and D2O and the other--absolutely not, we have calculated the portion of either group in the protein fluorescence (alpha and 1-alpha, correspondingly). Measurement of murine lens homogenates fluorescence at different stages of radiation-induced cataract, initiated with total gamma irradiation in a dose 5 Gy have shown an increased accessibility of tryptophanyl for water with cataract development. At earlier stages of cataract (appearance of scattered dot opacities) the portion of water-accessible tryptophanyl increased from 0.14 to 0.18, i.e. by a factor of 1.3. The data obtained suggest that protein globules unfold in the coarse of cataract development.     

Specific modification of the alpha-subunit of Escherichia coli Rna polymerase by monomercuric derivative of fluorescein mercuric acetate

The method for specific modification of Escherichia coli RNA polymerase by a monomercuric derivative of fluorescein--fluoresceinmonomercuracetate (FMMA)--a specific reagent for SH-groups of proteins is suggested. It is shown, that in conditions of equimolar FMMA/enzyme ratio the fluorescent label interacts preferantially with a single sulfhydryl group in alpha-subunit of RNA polymerase. The mercaptide bonding formation is followed by significant alterations of all spectral parameters of FMMA, but has no effect on the kinetic parameters (KB and k2) of RNA synthesis initiation nor does it lead to inhibition of the total RNA synthesis. The modification presented may be used in structural and topological investigations of RNA polymerase functioning.