PRODUCTS OF CHLOROPHYLL PHOTODEGRADATION–1. DETECTION and SEPARATION

Abstract— The photodegradative fate of ¹⁴C-radiolabelled phaeophytin a adsorbed on hydrophobic particles in an aqueous suspension is followed. An approximate mass balance is made for the hydrophilic, hydrophobic and CO, fractions. In addition, components of the colourless hydrophilic fraction produced from photodegrading chlorophyll a, phaeophytin a, phaeophorbide a and chlorophyll b are detected and separated using reverse-phase ion-pair and ion-exclusion HPLC with UV detection. The increase in the hydrophilic molecules and the decrease in chlorophyll a are measured as the photodegradation proceeds.     

芳香聚酰胺纤维的结构鉴定方法研究

用红外光谱方法分析了聚对苯甲酰胺(Ⅰ)和聚对苯二甲酰对苯二胺(Ⅱ)的谱带特征及其与结构的关系,指出了两者的区别,并用二向色性观察了薄膜的取向态,改进了化学分析方法,从(Ⅱ)的水解产物中分离和鉴定了对苯二甲酸和对苯二胺,确定了Kevlar-49纤维的结构属于(Ⅱ),还用差热分析方法比较了T_m和T_d等数据。     

SYNTHESIS OF GLYCOSYLAMINES: IDENTIFICATION AND QUANTIFICATION OF SIDE PRODUCTS

The synthesis of some glycosylamines (1-amino-1-deoxy D-glucose, 1-amino-1-deoxy-D-galactose and 1-amino-1-deoxylactose) was carried out by treatment of the corresponding reducing sugars with ammonium hydrogencarbonate in concentrated ammonia. The reaction mixture was first analyzed by capillary electrophoresis with indirect absorbance detection and high performance anion-exchange chromatography with pulsed amperometric detection. Beside glycosylcarbamate, a known reaction by-product, fructose and lactulose were detected during the synthesis of 1-amino-1-deoxyglucose and 1-amino-1-deoxylactose, respectively. Quantification of glycosylamines was carried out by micellar electrokinetic chromatography with UV detection of their 9-fluorenylmethyloxycarbonyl (Fmoc) derivatives; lactulosylamine was thus detected in the synthesis mixture of 1-amino-1-deoxylactose. The Fmocglycosylamines were easily purified from the other components of the crude synthesis mixtures.     

SULFOPHTHALOCYANINES FOR PHOTODYNAMIC INACTIVATION OF VIRUSES IN BLOOD PRODUCTS: EFFECT OF STRUCTURAL MODIFICATIONS

Abstract— Transmission of infectious diseases through blood transfusions is well known. Ultraviolet irradiation, solvents and detergents provide a means of sterilizing noncellular blood components. However these harsh methods are not applicable to cellular blood products. Recently, attempts have been made to sterilize biological fluids using photodynamic treatment and phthalocyanine (Pc) dyes have been advanced as photosensitizers for this purpose. We have evaluated a series of water-soluble Pc, chelated with different central metal ions, substituted to different degrees with sulfonato and r-butyl groups, for their effectiveness to reduce virus infectivity in red blood cell suspensions. Vaccinia virus cytopathogenicity was determined by endpoint serial dilutions in the CV-1 cell line. Anti-viral activity increased with the central metal ion in the following order: Ga(III) < Al(III) < Zn(II), and varied inversely with the degree of sulfonation. Furthermore, addition of a t -butyl group onto the trisulfonated dyes (PcS₃[ t -Bul) resulted in a 5–40-fold increase in anti-viral potency, suggesting that amphiphilicity enhances the photodynamic activity of the dye. Strong anti-viral photosensitizing properties cannot be the sole selection criterion. Of equal importance is the preservation of blood component integrity. Accordingly, the photohemolytic activity of the dyes was evaluated using the rate of hemolysis as a parameter and a toxicity index was defined. Among the most active dyes, the AlPcS₃( t -Bu) complex exhibited the most favorable anti-viral properties combined with a low toxicity index. Our results suggest that trisulfophthalocyanines, bearing an additional t -butyl group to enhance amphiphilicity, are particularly promising dyes for photodynamic blood sterilization.     

CHLOROPHYLL METABOLISM IN ETIOLATED GHERKIN SEEDLINGS I. PHOTOINHIBITION OF CHLOROPHYLL ACCUMULATION

Abstract. Cotyledons of etiolated gherkin seedlings do not turn green upon transfer to high intensity red light (about 25 W/m²). A pre-irradiation with high intensity red light has an after-effect as chlorophyll accumulation during a subsequent exposure to white light (20 W/m²) is inhibited.
The capacity of protochlorophyll regeneration during a dark period depends on the length of a previous light period but is hardly affected by the light intensity. At high intensity light the rate of protochlorophyll regeneration, which also depends on the length of the foregoing irradiation, is lower than that at low intensity light only during the first 1.5h of the light period. It is concluded that high intensity red light inhibits chlorophyll accumulation mainly by photo-bleaching of chlorophyll. The after-effect is the result of a photooxidation which may lead to photo-bleaching of newly formed chlorophyll in relatively low intensity light.
Photoinhibition of chlorophyll accumulation is accompanied by a disturbed development of etioplasts into chloroplasts.     

ASSOCIATION OF CHLOROPHYLL WITH AMIDES ON PLASTICIZED POLYETHYLENE PARTICLES–III. UNUSUAL SPECTRA OF CHLOROPHYLL a WITH N-METHYLMYRISTAMIDE*

—The absorption spectrum of chlorophyll a, adsorbed with the amphiphilic amide, N-methylmyristamide. to particles of polyethylene swollen with tetradecane, is unusual in that the red band apparently consists of three main components, which by Gaussian deconvolution are located at 664.5, 678 and 687 nm. The last is very narrow, with a band width of only 5-6 nm at half maximum. At low amide concentration, the 744 nm band of chlorophyll hydrate is also observed. Room temperature fluorescence is weak, and indistinctly resolved into bands. However, on gradual cooling to 80 K, the fluorescence intensifies greatly and becomes resolvable into at least eight bands. The circular dichroism spectrum of the red band region shows optical rotatory strength in two narrow bands at 677 and 686 nm which is enormous, compared to that of monomeric chlorophyll or even the 744 nm hydrate. It is suggested that cyclic oligomer structures, in which adjacent chlorophylls are linked through the amide group of N-methylmyristamide, might be responsible for the spectral phenomena. Unsubstituted myristamide and N.N-dimethylmyristamide do not produce these narrow-banded phenomena with chlorophyll at all.     

生理条件下对苯二酚的电化学行为及电极产物的色谱鉴定

用循环伏安法研究了对苯二酚在玻碳电极上的电化学行为,从循环伏安图上看出当在0至1．6V电位间连续扫描20次,在0．63V左右可见到一氧化峰电位,其峰电流随扫描次数的增加而减小。说明电极反应为不可逆过程。然而,如改变在-1．4～1.6V电位间扫描,仅数次扫描后即可在Epa=0．25V和Epc=-0．08V处见到一对氧化还原峰电位,说明了此过程为一可逆过程。同时,对电极反应的产物用RHPLC进行研究和鉴定,从色谱图所示结果与电化学法所得结果一致。根据此工作的研究结果对苯二酚在呼吸链中所产生的作用进行了探讨。     

繁峙煤镜质组的生烃特征与热解产物生成动力学研究

本文利用付立叶红外光谱（ＦＴＩＲ），热解气相色谱（Ｐｙ－ＧＣ）及热解气相色谱质谱（Ｐｙ－ＧＣ－ＭＳ）联用技术等分析手段，探讨了我国山西繁峙煤镜质组的生烃特征，鉴定了如气体烃、正构脂肪烃、苯酚、单环芳烃以及甲氧基酚类等热解产物６７种化合物。用相继等温热解法一级反应动力学模型，求取了热解产物如气体组分（Ｃ１￣Ｃ６）、轻烃（Ｃ７￣Ｃ１４）、重烃（Ｃ１５￣Ｃ３０）、正构脂肪烃（ｎＣｉ）、烷基芳烃、苯酚等的     

DARK EXCITATION OF CHLOROPHYLL

Abstract— Enzyme generated triplet acetone transfers its energy to Chl a to form the first excited singlet of the acceptor, as shown by the suppression of the acetone chemiphosphorescence and concomitant appearance of the Chl fluorescence.     

CHLOROPHYLL ONE-ELECTRON PHOTOCHEMISTRY-I. PHOTOPRODUCTION OF THE CATION RADICALS OF CHLOROPHYLL AND BACTERIOCHLOROPHYLL IN SOLUTIONS AT LOW TEMPERATURES*

Abstract— Electron spin resonance studies have shown that chlorophyll and bacteriochlorophyll can be photo-oxidized in a variety of solvents via their lowest excited singlet states to produce cation radicals. Pheophytin does not undergo this reaction. The mechanism of this photoprocess and its implications for photosynthesis are discussed.     

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.     

PHOTOSENSITIZATION WITH DERIVATIVES OF CHLOROPHYLL

The properties of several chlorophyll derivatives were examined: the methyl esters of pheophorbide A, pheophorbide B and pheophytin. In spite of structural differences, all products were equally effective sensitizers in vitro and were localized equally well by murine tumors in vivo after 1 h. But only the pheophytins persisted at neoplastic loci for 24 h. There was no evidence of hydrolysis of the methyl esters, but the phytyl ester linkage was labile in vivo.     

EXCITATION OF CHLOROPHYLL DURING THE PEROXIDASE-CATALYZED OXIDATION OF ETHYL α-FORMYLPHENYLACETATE

Abstract When micelle-solubilyzed chlorophyll is present during the horseradish peroxidase catalyzed aerobic oxidation of ethyl α-formylphenylacetate its fluorescence is observed. The excitation of chlorophyll may occur via energy transfer from the enzyme-generated triplet ethyl benzoylformate. These results imply that excited states may be generated in the roots of Datura innoxia .     

辐照肉制品中2-十二烷基环丁酮的测定

采用GB/T 21926-2008《辐照含脂食品中2-十二烷基环丁酮测定气相色谱/质谱法》对辐照肉制品中的2-十二烷基环丁酮进行测定,鉴别辐照肉制品。样品用索氏抽提,经冷冻离心和弗罗里硅土层析净化,用气相色谱质谱联用法测定。2-十二烷基环丁酮的浓度在0.01~0.5 mg/L与色谱峰面积呈良好的线性关系,r=0.999 6。对未经辐照的样品进行加标回收试验,加标回收率为83.1%~94.0%,测定结果的相对标准偏差小于6%(n=6)。     

PHOTOVOLTAIC EFFECT OF CHLOROPHYLL a–QUINONE SYSTEMS IN MULTILAYER ARRAYS

Abstract— Photovoltaïc cells made of an array of chlorophyll a (Chi a ) monolayers between an aluminum and a silver electrode have been analyzed. These cells are characterized by charge carrier production due to the dissociation of singlet excitons. The exciton diffusion length λ∼ 300 ± 100 Å. The optimum thickness of these cells consists of an array of 44 monolayers for which a power conversion efficiency η= 0.038% and a quantum yield ø= 0.49% has been measured at 678 nm using an incident light intensity of 0.3 W/m². In these cells, about 60% of the collected charges are generated by the exciton dissociation in the bulk of the semiconductor and 40% by the exciton dissociation at the aluminum electrode. The behaviour of Chl a photovoltaïc cells doped with two quinones has also been analyzed. The two quinones are vitamin K¹ and N,N-distearoyl-1,4-diaminoanthraquinone (SAQ). The photovoltaic properties of Chi a remain practically unchanged when quinone is not in the same monolayer as Chi a. But when Chi a and quinone are in the same monolayer, up to a molecular ratio of 1:0.3, there is a drastic decrease in the efficiencies and quantum yields of the cells. The photovoltaïc behaviour varies in parallel with the extinction of Chi a fluorescence by the quinones in contrast with what is reported for strong electron acceptors adsorbed on photoconductors. An electron transfer from the singlet state of Chi a to the quinones is proposed on the basis of the variation in the quantum yield for current production with the energy of the incident photon.     

STRUCTURAL RELATIONSHIPS OF THE PHOTOSYSTEM I AND PHOTOSYSTEM II CHLOROPHYLL a/b AND a/c LIGHT-HARVESTING APOPROTEINS OF PLANTS AND ALGAE

Polyclonal antibodies against four different apoproteins of either the chlorophyll (Chl) a/b light-harvesting antenna of photosystem I or II, or a chlorophyll-protein complex homologous to CP26 from Chlamydomonas reinhardtii, crossreact with11–13 thylakoid proteins of Chlamydomonas, Euglena gracilis and higher plants. The number of antigenically-related proteins correlates with the quantity of light-harvesting chlorophyll-protein complex (LHC) gene types that have been sequenced in higher plants. The antibodies also react specifically with Chi a/c-binding proteins of three diatoms and Coccolithophora sp. as determined by immunoblot and Ouchterlony assays. Four to six crossreacting proteins are observed in each chromophyte species and a functional role for some can be deduced by antibody reactivity. It appears that despite major differences in the structures of their pigment ligands, at least some domains of Chl-binding LHC apoproteins have been conserved during their evolution, possibly functioning in protein: protein, as opposed to pigment: protein, interactions in photosynthetic membranes.     

INVESTIGATION OF THE ALLOMERIZATION REACTION OF CHLOROPHYLL a: USE OF DIODE ARRAY HPLC, MASS SPECTROMETRY AND CHEMOMETRIC FACTOR ANALYSIS FOR THE DETECTION OF EARLY PRODUCTS

Abstract –The products of chlorophyll allomerization in methanol were isolated and analyzed by open column sucrose chromatography, liquid chromatography mass spectrometry (LCMS) and DAD-HPLC (diode-array high-performance liquid chromatography). Four main bands were found with molecular ions of (a) 908, (b) 938, (c) 938 and (d) 938, consistent with the structures (a) 13²-hydroxy-chlorophyll a (II), (b) and (c) Mg(II)-3¹,3²-didehydro-15¹-hydroxy-15¹-methoxy-rhodochlorin-15 acetic acid δ-lactone 15²-methyl 17³-phytyl ester and its epimer (III) and (d) Mg(II)-3¹,3²-didehydro-rhodochlorin-15-glyoxylic acid 13¹,15²-dimethyl 17³-phytyl ester (IV), evidence enhanced by UV/visible spectroscopy, chromatographic coelutions and chemometrics. Chlorophyll a was degraded both in the dark and light, under O₂ and N². DAD-HPLC of the resultant degradation mixtures were analyzed using the chemometric heuristic-evolving latent projection method for resolution. Ultraviolet/visible spectra of II and III are reproducibly extracted from the mixtures after a short degradation time, whereas III and IV are the dominant compounds after longer degradation times. Changes in relative elution order of IV using open column chromatography and reverse-phase HPLC are established. A possible allomerization pathway is proposed.