Isamu Inamura

PREPARATION AND PROPERTIES OF CHLOROPHYLL/WATER-SOLUBLE MACROMOLECULAR COMPLEXES IN WATER. STABILIZATION OF CHLOROPHYLL AGGREGATES IN THE WATER-SOLUBLE MACROMOLECULE

Abstract— As an artificial model compound of the chlorophyll‐protein complex in vivo, the chlorophyll/water‐soluble macromolecular complexes were prepared by using synthetic linear polymers of polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene glycol (PEG), and a natural polymer of bovine serum albumin (BSA). By the method described here, it is possible to prepare an aqueous chlorophyll (Chl)‐macromolecular complex solution of a desired Chi aggregate, such as: Chi a(670), Chi a(740) and Chi b; and with a desired relative content and concentration. These procedures for preparing such complexes will have wide applicability for technical use in Chi studies. For example, extremely diluted aqueous complex solutions of at least 1 × 10‐4% wt Chi a(670 or 740)‐macromolecular complex / wt can be obtained without changing the spectral features. From viscosity measurements, the structures of the complexes were inferred: (1) for a linear macromolecular (PVA or PVP) complex, a Chi species is tightly surrounded by a chain of the polymer causing shrinkage of the chain; (2) globular BSA molecules surround Chi species to form a large complex. The mechanism of stabilization of Chi aggregates in thylakoid membrane was discussed concerning an analogy to the complexes studied here.

Preparation and properties of the water-soluble chlorophyll-bovine serum albumin complexes

By mixing chlorophyll (Chl) a or b with a dense bovine serum albumin solution, the water-soluble Chl-bovine serum albumin complexes were prepared. These complexes, eluted near the void volume on a gel filtration, were separated well from unreacted bovine serum albumin, indicating an aggregation of such molecules in the complexes. Preparation of chlorophyllide (Chlide) a- or Chlide b-bovine serum albumin complex was unsuccessful, while the phytol-, and beta-carotene-bovine serum albumin complexes could be obtained. Chls in the Chl-bovine serum albumin complexes had the following characteristics. Main absorption peak of Chl a or b in the red region occurred at 675 nm or 652 nm, respectively. The Chl a-bovine serum albumin complex having absorption peak at 740 nm was also prepared. As compared with the stabilities of Chl a and b in Triton X-100. Both Chls in the bovine serum albumin-complexes were stable against oxidative stresses, such as photobleaching, Fenton reagent, peroxidase-H2O2 system. But they were easily hydrolyzed by chlorophyllase. These properties of Chls in the bovine serum albumin-complexes were similar to those of Chls in the isolated light-harvesting Chl a/b protein complex. A possible localization of Chls within the bovine serum albumin complexes was suggested that the porphyrin moiety of Chl was buried in bovine serum albumin; however, the hydrophilic edge of porphyrin ring, adjacent to the phytol group, occurred in the hydrophilic region of a bovine serum albumin molecule.

Diastereoselective [3+2]-photocycloaddition of chiral 1,4-naphthalenedicarboxylic esters to alkenes

Abstract [3+2]-Photocycloaddition of di-(−)-menthyl, di-(−)-8-phenylmenthyl, and di-(−)-bornyl 1,4-naphthalenedicarboxylates to alkenes, such as isobutene, styrene, and α-methylstyrene, proceeded with diastereoselectivity, up to 62% diastereomeric excess (de), largely depending on the concavity of the auxiliary, steric bulk of the substituents of the alkenes, and reaction temperature. The de values remarkably increased with decrease of the reaction temperature, and linear dependence of In(diastereomeric ratio) on 1/T was observed.

Miscibility of Semirigid Liquid‐Crystalline Polycarbonate with Poly(vinyl alcohol), Partially Saponified Poly(vinyl acetate) or Poly(vinyl acetate)

The miscibility in blends of semirigid liquid-crystalline polycarbonate (LCPC) with poly(vinyl alcohol) (PVA), partially saponified poly(vinyl acetate) (PVAc75) and poly(vinyl acetate) (PVAc) was investigated by means of differential scanning calorimetry and scanning electron microscopy. These measurements suggested that LCPC forms partially miscible blends with PVA and PVAc75. Blends of PVAc are immiscible. The side-chain hydroxy groups play an important role in improving the miscibilities of the blends.

3+2-PHOTOCYCLOADDITIONS OF DICYANONAPHTHALENES TO ALKENES

Abstract [3+2]-Photocycloadditions of 1,2-, 1,3-, and 2,3-dicyanonaphthalenes to alkenes were found to proceed at the 1,8-, 4,5-, and 1,8-positions of the naphthalene ring of dicyanonaphthalenes, respectively. In the photoreactions of the 1,3- and 2,3-isomers [3+2]-adducts were obtained in oxidized forms and addition of Cu(OAc) 2 considerably improved the yields of the adducts. The observed addition sites of the alkenes are rationalized on the basis of the spin and charge densities of the radical anions of dicyanonaphthalenes.

Relation between Huggins Constant and Compatibility of Binary Polymer Mixtures in the Aqueous Ternary Systems

We have classified a number of aqueous ternary systems containing two different polymers into three types by focusing on the deviation of the Huggins constantk′ from the additivity line. Systems of type I have negative deviations ofk′; the repulsive interaction between the two different polymers dominates. In systems of type II,k′ almost follows the additivity relation; the repulsive and attractive interactions between the two different polymers are balancing. Type III systems have positive deviations ofk′; the attractive interactions are relatively dominant. This classification of systems is supported by the fact that the positive and negative deviations ofk′ from the additivity line also correspond to the sign of interaction parameter between polymer 2 and 3, Δb23. Furthermore, we have verified the relatively high compatibility between dextran and poly(vinyl alcohol) by determining the binodal concentration of a liquid-liquid phase separation for a water/dextran/poly(vinyl alcohol) system, which is classified as type III. Thus, we found that the compositional dependence ofk′ closely relates to the compatibility of binary polymer mixtures in aqueous ternary systems.

Properties of the water-soluble chlorophyll-synthetic linear macromolecular complexes

Abstract The properties of the water-soluble chlorophyll (Chl) a or b-synthetic linear macromolecular (poly(vinylpyrrolidone)(PVP), poly(ethylene glycol)(PEG) or poly(vinyl alcohol)(PVA)) complexes were investigated. The low-temperature (77 K) fluorescence emission spectra suggested that the Chl a or b-PVP and Chl b-PVA complexes had the similar form of Chl a or b to that of Chl a or b in ethyl ether or Triton X-100, probably a monomeric form, while the Chl a or b-PEG and Chl a-PVA complexes contained the several undefined forms of Chl a or b. The Chl a-PVP complex was eluted at the same volume of the corresponding PVP applied independently to a column of Sephadex G-100, but the Chl a-PEG and Chl a-PVA complexes showed the elution patterns similar to that of Chl a-bovine serum albumin (BSA) complex. The Chls in the synthetic linear macromolecular complexes were stable against oxidative stress of photobleaching, but they were easily hydrolyzed by chlorophyllase, as were the Chls in both the BSA complexes and the isolated light-harvesting Chl a b- protein complex (LHC). A possible localization of Chls within linear macromolecular complexes was suggested so that the tetrapyrrole ring and phytol group of Chl would be surrounded by a linear macromolecular (PVP) chain or a number of linear macromolecular (PEG or PVA) chains, whereas the hydrophyllic edge of porphyrin ring, adjacent to the phytol group, would be exposed to the environment of a water medium.

INTRAMOLECULAR 3+2-PHOTOCYCLOADDITIONS OF ALKENYL METHYL 1,4-NAPHTHALENEDICARBOXYLATES

Abstract Intramolecular [3+2]-photocycloadditions of alkenyl methyl 1,4-naphthalenedicarboxylates, which contain rather remote alkene moieties corresponding to isobutene or α-methylstyrene, proceeded largely depending on the chain lengths to give [3+2]-adducts having nine- to eleven-membered ring systems as well as the characteristic five-membered ring structures. Intramolecular quenching of the fluorescence of the diester moiety by the alkene moiety was observed in response to the occurrence of the [3+2]-photocycloadditions.