Restriction enzymes Ecl18kI, PspGI and EcoRII-C, specific for interrupted 5-bp target sequences, flip the central base pair of these sequences into their protein pockets to facilitate sequence recognition and adjust the DNA cleavage pattern. We have used time-resolved fluorescence spectroscopy of 2-aminopurine-labelled DNA in complex with each of these enzymes in solution to explore the nucleot...

Sub-surface tomography with diffuse light has been investigated with a non-contact approach to characterize the performance of optical absorption and fluorescence imaging. Using both simulations and experimental studies, the reconstructed images of local sub-surface heterogeneities was demonstrated, using diffusion properties characteristic of near-infrared light in mammalian tissue. The result...

The combining region of Artocarpus integrifolia lectin has been studied by using the ligand-induced changes in the fluorescence of the lectin. The saccharide binding properties of the lectin show that C-1, C-2, C-4, and C-6 hydroxyl groups of D-galactose are important loci for sugar binding. The alpha-anomer of galactose binds more strongly than its beta-counterpart. Inversion in the configurat...

Fluorescence studies have been performed on the interaction of papain with active-site-directed inhibitors of the type mansyl-(Gly)n-Phe-glycinal, where n = 0, 1, 2. It has been found that whereas the mansyl [6-(N-methylantilino)-2-naphthalene sulfonyl] fluorescence of mansyl-Phe-glycinal is greatly enhanced, that of the two longer mansyl compounds is not, although all three are equally effecti...

Measurements have been performed of the excited-state lifetimes and fluorescence yields of papain tryptophan units when acyl derivatives of Phe-glycinal are bound at the active site of the enzyme. The enhancement of tryptophan fluorescence in complexes of papain with the acetyl or benzyloxycarbonyl derivatives is not stereospecific with respect to the configuration of the phenylalanyl residue, ...

The homo and hetero dimerisation of two spectroscopically different chromophores were studied, namely: 4,4difluoro-4-bora-3a,4a-diazas-indacene (g-BODIPY) and its 5-styryl-derivative (r-BODIPY). Various spectroscopic properties of the r-BODIPY in different common solvents were determined. It was shown that gand r-BODIPY in the ground state can form homoas well as hetero dimers. We demonstrate t...

To test for possible differences in local conformation and S1 flexibility, bovine cardiac and rabbit skeletal myosins were labeled with a fluorophore (1,5-IAEDANS) and a spin label having iodoacetamide reactivity. The marked activation of the Ca2+-ATPase (6- to 8-fold) and inhibition of the K+ (EDTA)-ATPase (80-90%) by both labels indicated specific labeling of the fast-reacting thiols (SH1) of...

Abstract: Anions are ubiquitous in nature and play significant roles in both chemistry and biology. Therefore, anion sensing has become an important area of research in recent years. Although several classes of anion sensors are known in the literature, polyamines are still considered are effective systems to bind anions strongly. During this research work, a thiophene-based azamacrocycle has b...

We present results from composite plasmonic nanostructures designed to achieve the cascaded enhancement of electromagnetic fields at optical frequencies. Our structures comprise a small metallic nanodisc suspended above a larger disk. We probe the optical properties of these structures by coating them with a layer of a visible-light fluorophore and observing fluorescence signals with the help o...

Synchronous fluorescence (SF) spectra of dissolved organic matter (DOp/I) show promise for mixing studies and can resolve multiple river inputs to large water masses in a single fast measurement. This study examines the effects of physicochemical variables on DOM SF independent of mixing. Our results show that changes in the pH and metal ion concentration do not affect SF in the alkaline Cuyaho...