Munenori Takehara

Biosynthesis of nearly monodispersed poly(ε-l-lysine) in Streptomyces species

Poly(ε-l-lysine) (ε-PL) is a naturally occurring poly(amino acid) characterized by a unique structure linking ε-amino and carboxyl groups of l-lysine. Due to its various functions and its biodegradability and non-toxicity, the ε-PL polymer has attracted increasing attention in recent years. ε-PL is frequently found in various strains of Streptomyces sp. This review gives an up-to-date overview regarding the biosynthesis of ε-PL focussing mainly on results obtained from ten newly isolated producer strains, using the two-stage culture method of cell growth and ε-PL production cultures. The production of nearly monodispersed ε-PL is covered together with the development of ε-PL specific hydrolases and the release of synthesized ε-PL into the culture broth. From these results, coupled with the termination of polymerization through nucleophilic chain transfer, the biosynthetic mechanism of the polymer is discussed.

Spectral characterisation of Z-isomers of lycopene formed during heat treatment and solvent effects on the E/Z isomerisation process.

The geometric isomerisation of (all-E)-lycopene, purified from tomato paste, was investigated in various organic solvents. Isomerisation ratios to the Z-isomers of lycopene in CH2Cl2 and CHCl3 over 24h were calculated to be 19.7% and 11.4% at 4°C and 77.8% and 48.4% at 50°C, respectively. In CH2Br2, more than 60% was attained in the first several hours, independent of temperature. The predominant Z-isomers obtained thermally, (9Z)-lycopene and (13Z)-lycopene, were purified and their absorption maxima and molar extinction coefficients in hexane were determined for the first time. Absorption values at 460 nm were also measured for both Z-isomers along with (all-E)-lycopene to accurately evaluate their concentrations by HPLC analysis. This approach successfully revealed that (13Z)-lycopene formed predominantly in benzene or CHCl3 at 50°C; in contrast, the 5Z-isomer was preferentially obtained in CH2Cl2 or CH2Br2.

Characterization and Thermal Isomerization of (all-E)-Lycopene

A large amount of (all-E)-lycopene was successfully purified from tomato paste using an improved method that included a procedure to wash crystalline powder with acetone. The total yield of the pure (all-E) form was at least 30%. The melting point of (all-E)-lycopene was determined to be 176.35 °C by differential scanning calorimetry (DSC) measurements. Bathochromic shifts were observed in the absorption maxima of all solvents tested (at most a 36 nm shift for λ2 in carbon disulfide, as was observed in hexane) and were accompanied by absorbance decreases, namely, a hypochromic effect, showing a higher correlation between the position and the intensity of the main absorption bands. This bathochromic shift was dependent upon the polarizability of the solvent rather than its polarity. The structure of (all-E)-lycopene in CDCl3 and C6D6 was identified on the basis of one- and two-dimensional nuclear magnetic resonance (NMR) spectra, including (1)H and (13)C NMR, homonuclear correlation spectroscopy ((1)H-(1)H COSY), heteronuclear multiple-quantum coherence (HMQC), and heteronuclear multiple-bond connectivity (HMBC). The rate constants of the decrease in (all-E)-lycopene with hexane and benzene were calculated to be 3.19 × 10(-5) and 3.55 × 10(-5) s(-1), respectively. The equilibrium constants between (all-E) and (13Z) isomers were estimated to be 0.29 in hexane and 0.31 in benzene, respectively, from the point at which the amount of (13Z)-lycopene reached its maximum.

Substantially monodispersed poly(ɛ-l-lysine)s frequently occurred in newly isolated strains of Streptomyces sp.

The presence of poly(ɛ-l-lysine) (ɛ-PL) was found quite frequently by screening various strains of Streptomyces sp. Most of the ten newly obtained ɛ-PLs, when they were produced from glucose, showed a polydispersity index of Mw/Mn = 1.01 using ion-pair chromatography analysis. The polymers were classified into five groups according to their chain lengths. The average numbers of residues in the five groups were 32, 28, 25, 19, and 16, respectively. The use of glycerol instead of glucose resulted in decreases of 10 to 20% in the Mn and slight increases in the Mw/Mn. These observations indicated the chain length and polydispersity of ɛ-PL were primarily determined by each producer strain. Proton and 13C NMR analysis revealed the signals of glycerol-derived ester at the C terminus of the polymer from several producers including the first discovered S. albulus strain, although the percentages of the ester were low under our culture conditions. These results, coupled with the previous observation that % MathType!Translator!2!1!AMS LaTeX.tdl!TeX -- AMS-LaTeX! % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX % garmWu51MyVXgatuuDJXwAK1uy0HwmaeHbfv3ySLgzG0uy0Hgip5wz % aebbnrfifHhDYfgasaacH8qrps0lbbf9q8WrFfeuY-Hhbbf9v8qqaq % Fr0xc9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qq % Q8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeWaeaaakeaaca % qGtbGaae4tamaaDaaaleaacaqG0aaabaGaaeOmaiabgkHiTaaaaaa!3BBE!

Isolation and spectral characterization of thermally generated multi-Z-isomers of lycopene and the theoretically preferred pathway to di-Z-isomers

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Photosensitized E/Z Isomerization of (all-E)-Lycopene Aiming at Practical Applications

was essential for the polymer production, led to discussion on the mechanistic aspects of monomer activation, elongation, and termination in the biosynthesis of ɛ-PL.

A novel alkaline esterase from Sporosarcina sp. nov. strain eSP04 catalyzing the hydrolysis of a wide variety of aryl-carboxylic acid esters.

Two poly(epsilon-L-lysine) (epsilon-PL) producer strains of Streptomyces celluloflavus secreted a novel polymeric substance into their culture broths along with epsilon-PL. Three types of HPLC analysis plus one- and two-dimensional 1H and 13C nuclear magnetic resonance experiments revealed that the secreted substance was poly(gamma-L-diaminobutanoic acid) (gamma-PAB), an L-alpha,gamma-diaminobutanoic acid (L-DAB) homopolymer linking between y-amino and alpha-carboxylic acid functional groups. The gamma-PABs from the two strains had an identical chemical structure, and the same number-average molecular weight of 2100-2200. No copolymers composed of the two amino acids L-DAB and L-lysine were found in either of the broths from the producers. Both strains coproduced high levels of the two poly(amino acid)s in the presence of SO4(2-) at pH 4.0 and 4.5 L min(-1) aeration in a 5-L jar fermentor. gamma-PAB exhibited strong inhibitory activities against various yeasts and weaker actions against bacteria than epsilon-PL. gamma-PAB may have various biological functions similar to epsilon-PL, and the use of gamma-PAB along with epsilon-PL would be advantageous for technical applications in various fields.

Crystal structure of 1,4-dieth­oxy-9,10-anthra­quinone

Lycopene has a large number of geometric isomers caused by E/Z isomerization at arbitrary sites within the 11 conjugated double bonds, offering varying characteristics related to features such as antioxidant capacity and bioavailability. However, the geometric structures of only a few lycopene Z-isomers have been thoroughly identified from natural sources. In this study, seven multi-Z-isomers of lycopene, (9Z,13′Z)-, (5Z,13Z,9′Z)-, (9Z,9′Z)-, (5Z,13′Z)-, (5Z,9′Z)-, (5Z,9Z,5′Z)-, and (5Z,9Z)-lycopene, were obtained from tomato samples by thermal isomerization, and then isolated by elaborate chromatography, and fully assigned using proton nuclear magnetic resonance. Moreover, the theoretically preferred pathway from (all-E)-lycopene to di-Z-isomers was examined with a computational approach using a Gaussian program. Fine-tuning of the HPLC separation conditions led to the discovery of novel multi-Z-isomers, and whose formation was supported by advanced theoretical calculations. Graphical abstract Isolation and characterization of novel (multi-Z)-lycopene, and a possible potential energy diagram for the formation to the isomer.