A Dual Alkylated Peptide-ligand Enhances Affinity to Human Serum Albumin.

Therapeutic peptides and diagnostic agents with their molecular size below the renal clearance threshold suffer from short blood circulation time. Here, we report a novel design of peptide-based ligand with a strong binding affinity to human serum albumin (HSA), which can be used as a tag to extend the blood circulation of small-size molecules. We designed ligands with dual alkyl groups connected with a negatively charged spacer.

Electrochemical Control of Bioluminescence by Blocking the Adsorption of the Bacterial Luciferase Using a Mercaptobipyridine Self-assembled Monolayer.

An N-butyl-N'-(4-mercaptobutyl)-4,4'-bipyridinium (4BMBP) was modified on a gold electrode to improve the electrochemical control of the bacterial luciferase (BL) luminescence system. The 4BMBP-modified gold electrode (4BMBP/Au) was able to prevent the adsorption of BL on the electrode surface, and enhanced the electrochemical regeneration rate of the reduced flavin mononucleotide (FMNH), which is one of the substrates of the BL luminescence reaction. By using the 4BMBP/Au, the luminescence intensity increased by about 27% compared to that of a bare gold electrode (bare Au).

Voltammetric study of the boric acid-salicylaldehyde-H-acid ternary system and its application to the voltammetric determination of boron.

The ternary system of boric acid, salicylaldehyde (SA) and H-acid (HA) was voltammetrically studied from kinetic and equilibrium points of view. The effect of the SA substituents was also studied by using two analogs, 5-fluorosalicylaldehyde (F-SA) and 5-methylsalicylaldehyde (Me-SA). The three cathodic peaks of Azomethine H (AzH), Azomethine H-boric acid complex (AzB), and free SA were observed in the solution containing boric acid, SA and HA.

Kinetic flow-injection analysis of boron using 5-fluorosalicylaldehyde and H-acid.

Boric acid reacts with 5-fluorosalicylaldehyde (F-SA) and 8-amino-1-naphthol-3,6-disulfonic acid (HA) to form the boric acid-fluoroazomethine H complex (F-AzB) that is now being used for the flow-injection analysis (FIA) of boric acid. At pH 6.5, the F-AzB complexation proceeded fairly fast, whereas the fluoroazomethine H (F-AzH) formation was slow.

Bioluminescence inhibition of bacterial luciferase by aliphatic alcohol, amine and carboxylic acid: inhibition potency and mechanism.

The inhibitory effects of hydrophobic molecules on the bacterial luciferase, BL, luminescence reaction were analyzed using an electrochemically-controlled BL luminescence system. The inhibition potency of alkyl amines, C(n)NH(2), and fatty acids, C(m)COOH (m = n - 1), on the BL reaction increased with an increase in the alkyl chain-length of these aliphatic compounds. C(m)COOH showed lower inhibition potency than C(n)NH(2) and alkyl alcohols, C(n)OH, data for which have been previously reported.

Immobilization of bacterial luciferase into poly(N-isopropylacrylamide) film for electrochemical control of a bioluminescence reaction.

A poly(N-isopropylacrylamide) film was modified on an indium-tin oxide electrode in order to immobilize bacterial luciferase (BL) on the electrode surface. By using the modified electrode, flavin mononucleotide (FMN) was electrochemically reduced to FMNH(2), which is one of the substrates of the BL luminescence reaction, to control the bioluminescence reaction by BL. The BL reaction in the modified film could be promoted and controlled by the electrochemical generation of FMNH(2).

Oxidation of chromium(III) by free chlorine in tap water during the chlorination process studied by an improved solid-phase spectrometry.

The oxidation of Cr(III) at naturally-occurring concentration levels, i.e., µg dm(-3) or lower levels, by free chlorine during the chlorination process of tap water was studied using an improved solid-phase spectrophotometric method, which can be directly applicable to the specific determination of Cr(VI) at µg dm(-3) or lower levels.

Inhibition of electrochemically controlled bioluminescence of bacterial luciferase by n-alkyl alcohols.

An electrochemical system has been developed in order to assay the effect of hydrophobic molecules on the bioluminescence of bacterial luciferase (BL). The inhibition of BL luminescence by the long-chain n-alkyl alcohol has been examined using this system. The 1-heptanol, 1-octanol, 1-nonanol, 1-decanol, 1-undecanol and 1-dodecanol inhibited the BL reaction in a dose-dependent manner.

Improved solid-phase spectrophotometry for the microdetermination of chromium(VI) in natural water.

A simple and sensitive solid-phase spectrophotometry procedure was improved for the microdetermination of Cr(VI). A 0.06 cm3 portion of a cation exchanger, Muromac AG 50W-X2, was used to concentrate the target Cr(VI) in a 20 cm3 water sample, and resin beads were introduced in a flow cell of 1.

Steady-state bioluminescence of bacterial luciferase using electrochemical regeneration of flavin substrate and its application to inhibitory analysis.

The model system for the biological reaction using a bacterial luciferase (BL) was developed and applied to the inhibitory analysis of the hydrophobic molecules for enzymatic reactions. The homemade flow electrochemical luminescence cell was embedded in the BL reaction system to regenerate the reduced form of the flavin mononucleotide, which is one of the substrates of the BL luminescence reaction, and to measure the luminescence intensity. The constant intensity of the continuous BL luminescence was observed using the continuous-flow BL reaction system.

Binding properties of hydrophobic molecules to human serum albumin studied by fluorescence titration.

Two fluorescence modes were combined to analyze the binding properties of terminally substituted alkanes (C(n)X, X = COOH, OH, CHO, NH(2)) to human serum albumin (HSA). A competitive binding assay using an 8-anilino-1-naphthalenesulfonate (ANS) fluorescence probe provides information on all the hydrophobic binding sites in HSA. A binding assay using the intrinsic fluorescence of the tryptophan residue in HSA (Trp-HSA) provides information on the specific binding site close to the tryptophan residue.

Classification of the binding modes in bovine serum albumin using terminally substituted alkane analogues.

With the fluorescence probe of 8-anilino-1-naphthalenesulfonate (ANS), the binding modes of terminally substituted alkane analogues (C(n)X; X = COOH, OH, CHO, NH(3), CONH(2)) to bovine serum albumin (BSA) were investigated using a competitive binding technique. The Scatchard plot of the fluorometric titration of BSA with ANS showed that the maximum binding number of ANS, n(max), was 3.81, with the binding constant, K(bnd), of 1.

On-line electrochemical oxidation of Cr(III) for the determination of total Cr by flow injection-solid phase spectrophotometry.

A novel on-line oxidation method of ultra-trace Cr(III) dissolved in natural water has been developed using a flow electrolysis cell. This method was successfully applied to the determination of the total Cr concentration by flow injection-solid phase spectrophotometry using diphenylcarbazide as a coloring agent. With the applied potential of 1.

Inhibition of firefly luciferase by alkane analogues.

We reported that anesthetics increased the partial molal volume of firefly luciferase (FFL), while long-chain fatty acids (LCFA) decreased it. The present study measured the actions of dodecanol (neutral), dodecanoic acid (negatively charged), and dodecylamine (positively charged) hydrophobic molecules on FFL. The interaction modes are measured by (1) ATP-induced bioluminescence of FFL and (2) fluorescence of 2-(p-toluidino)naphthalene-6-sulfonate (TNS).