Optical Rotatory Dispersion and Circular Dichroism of Amino Acid Hydantoins

Optical rotatory dispersion (ORD) and circular dichroism (CD) of 17 amino acid hydantoins were measured between 190 and 600 nm. Most of hydantoins exhibited the negative Cotton effect which showed the trough between 238 and 245 nm. The negative trough of CD was also observed between 212 and 236 nm. The Cotton effect of hydantoins was attributable to n→π^* transition of carbonyl group at C-4 of hydantoin ring.     

Application of Fluoresceinisothiocyanate Labeling of Protein to SDS-Electrophoresis and Subsequent Sequence Analysis

Fluoresceinisothiocyanate was applied to fluorescent labeling of protein for the determination of molecular weight by SDS Polyacrylamide gel electrophoresis. Proteins having molecular weight ranging from 15,000 to 70,000 were tested. The resolved FITC-labeled protein was eluted from the gel and was submitted to amino acid sequence analysis.     

Synthesis of N-(9-Acridinyl)maleimide,a Fluorometrical Reagent for Thiol Compounds

The authors have reported¹⁾ a new maleimide type fluorescent thiol reagent, N-(9-acridinyl)- maleimide (NAM). In this paper the syntheses of NAM and its coupling products with thiol compounds are presented. NAM was synthesized from 9-aminoacridine and maleic anhydride through dehydratic cyclization in polyphosphoric acid. NAM showed no substantial fluorescence but its coupling products with thiol compounds exhibited strong blue fluorescence. Application of NAM for the fluorometrical analysis of cysteine and glutathione are suggested.     

Circular Dichroism of Borate Complexes of Aldonic Acid γ-Lactones and Its Application to the Stereochemistry of Vicinal cis-Hydroxyl Groups in Lactone Rings

A method is reported, by chelate formation between borate ion and vic.-cis diols, to determine the configuration at Cβ in aldonic acid γ-lactones. Chelate formation is detected by red shift and decrease in the molar ellipticity of the CD maximum in borate buffer. It was also detected by the decrease in the rate of hydrolysis of the lactone ring at pH 9, as measured by the decrease in the CD maximum.     

Purification of cross-reacting protein antigen shared by Yersinia enterocolitica and other gram-negative bacteria with monoclonal antibody

A monoclonal antibody against the Yersinia enterocolitica 60-kilodalton (kDa) antigen, designated cross-reacting protein antigen (CRPA), was obtained by cell fusion. The CRPA common to gram-negative bacteria was purified from Y. enterocolitica by the affinity chromatography with the monoclonal antibody (IgG1) thus obtained. The purified CRPA showed a single band of 60 kDa in SDS-polyacrylamide gel electrophoresis (SDS-PAGE), and reacted with rabbit antisera against Y. enterocolitica, Vibrio cholerae, Escherichia coli, Pseudomonas aeruginosa, and Shigella sonnei in Western blot analysis. The monoclonal antibody, however, reacted with a 60 kDa peptide from Y. enterocolitica, but not with the antigens from other gram-negative bacteria such as V. cholerae, E. coli, S. sonnei, Salmonella enteritidis, Serratia marcescens, Klebsiella pneumoniae, Proteus mirabilis, and P. aeruginosa. The results suggested that both species-specific and cross-reactive epitopes were present on a CRPA molecule.     

Circular Dichroism of Trimethylsilyl Derivatives of Aldonic Acid-γ-lactones and the Influences of the Cα Substituent and Ring Conformations on the Sign and the Magnitude

Circular dichroism of trimethylsilyl (TMS) derivatives of seven aldonic acid-γ-lactones were studied. As well as original sugar-γ-lactones the sign of the Cotton effect was determined by the C–2 configuration. The magnitude of CD peak was found to be related with the ring geometry. It leads to a conclusion that the observed molecular elipticities may be the sum of two effects; one effect of configuration at C–2 and the other effect of ring geometry. If these two effects are of the same sign, they overlap each other and give a strong CD peak. When the sign of these effects are opposite, they cancel each other and hence give a weak CD peak. Between the two effects, when C–2 substituent is OH or OTMS, the effect of configuration at C–2 is stronger than that of ring geometry.     

Analytical Studies of Iodine in Food Substances

Four species of edible brown marine algae were fractionated by trichloroacetic acid precipitation and subsequent chromatography; and the iodine content of each fraction was determined. Quantitative determination of iodide form iodine was made possible by elimination of interfereing substances in cell extract using a weakly basic anion exchange resin column without drastic procedure.

Although the iodine content of each algae was of much diversity owing to species, the iodide form iodine varied between 83~85% of total iodine independent on total iodine content. The rest of the iodine was mostly found in trichloroacetic acid precipitate probably in protein bound form; and each algae contained little trichloroacetic acid soluble non iodide form of iodine, probably a low molecular organic form iodine.     

The Reaction Mechanism of Pyrimidine Nucleoside Synthesis by the Nitromethane Mercuric Cyanide Method

8,4?-dieckol is a natural product which has been isolated from brown alga, Ecklonia cava. This polyphenolic compound is a phlorotannin derivative with a broad range of bioactivities. Its inhibitory activity on human immunodeficiency virus type-1 (HIV-1) was tested and the results indicated that 8,4?-dieckol inhibited HIV-1 induced syncytia formation, lytic effects, and viral p24 antigen production at noncytotoxic concentrations. Furthermore, it was found that 8,4?-dieckol selectively inhibited the activity of HIV-1 reverse trancriptase (RT) enzyme with 91% inhibition ratio at the concentration of 50?μM. HIV-1 entry was also inhibited by 8,4?-dieckol. According to data from this study, 8,4?-dieckol is an effective compound against HIV-1 with high potential for further studies. These results suggest that it might be used as a drug candidate for the development of new generation therapeutic agents, although further studies on the mechanism of inhibition should be addressed.     

D-pantolactone as a circular dichromism (CD) calibration.

A critical study of circular dichromism (CD) measurement at the wavelength region around 220 nm was made. Test sample methods gave deviations of abou 20%, at most, between instruments calibrated at 290 nm with D-10-camphorsulfonic acid. A calculation of the CD from optical rotatory dispersion (ORD) data was made for d-pantolactone which gave a CD maximum at 219 nm, [θ]₂₁₉²⁵ = ?17.3 × 10³ in water. A proposal is made to use this value for calibration of CD in the 220-nm region.