不产氧光合细菌光合色素的光氧调控机制

[目的]为不产氧光合细菌光合色素研究提供可行的较系统规范的研究方法和数据,揭示固氮红细菌(Rhodobacter azotoformans 134K20)光合色素光氧适应性机制.[方法]采用光谱法和色谱法对光和氧调控下的类胡萝卜素和细菌叶绿素合成代谢进行了研究.[结果]134K20菌株光照好氧时细胞得率最高.光照厌氧时主要合成3黄、1红、1紫、2绿、2蓝9种色素,黄色素大量表达.有氧时红色素大量表达,且启动2种新的红色素和1种新的紫色素表达,而黄色和蓝绿色素则受氧抑制.黑暗好氧主要合成2黄、3红、2紫、1绿、1蓝9种色素,但不同于光照厌氧.光照好氧时黄色素减少到1种,紫色素含量增加,其余同黑暗好氧.[结论]固氮红细菌(Rhodobacter azotoformans 134K20)是通过PpsR调节途径来调节光合基因表达的.黄色和红色素属于类胡萝卜素.黄色素1属于球形烯系列,其余两种黄色素是新的类胡萝卜素组分.红色素为新的球形烯酮组分,3种红色素极性、峰形和峰位差别显著,正己烷能显示其精细结构.紫色为极性较大的细菌脱镁叶绿素,绿色和蓝色为4种极性不同的细菌叶绿素a中间产物.乙醚甲醇法适合类胡萝卜素的提取,丙酮甲醇冰冻研磨法能快速有效完全提取光合色素.溶剂效应可有效鉴别细菌叶绿素a中间产物.     

Production of water-soluble yellow pigments via high glucose stress fermentation of Monascus ruber CGMCC 10910

Monascus pigments are secondary metabolites of Monascus species and are mainly composed of yellow pigments, orange pigments and red pigments. In this study, a larger proportion of Monascus yellow pigments could be obtained through the selection of the carbon source. Hydrophilic yellow pigments can be largely produced extracellularly by Monascus ruber CGMCC 10910 under conditions of high glucose fermentation with low oxidoreduction potential (ORP). However, keeping high glucose levels later in the culture causes translation or a reduction of yellow pigment. We presume that the mechanism behind this phenomenon may be attributed to the redox level of the culture broth and the high glucose stress reaction of M. ruber CGMCC 10910 during high glucose fermentation. These yellow pigments were produced via high glucose bio-fermentation without citrinin. Therefore, these pigments can act as natural pigments for applications as food additives.

     

微生物产色素机制及其生物活性

近年来,随着人工合成色素的大量使用引起一系列环境和健康问题,增加了人们对安全、无毒天然色素的需求.天然色素主要来源于植物和微生物,由于植物生长周期较长使植物源色素在大规模应用中受限.与植物源天然色素相比,微生物源色素易于大规模快速培养,具有更广阔的应用前景.本文系统总结了不同微生物源色素产生机制,及其在抗菌、抗氧化及抗...     

Antioxidant capacity of novel pigments from an Antarctic bacterium

In Antarctica microorganisms are exposed to several conditions that trigger the generation of reactive oxygen species, such as high UV radiation. Under these conditions they must have an important antioxidant defense system in order to prevent oxidative damage. One of these defenses are pigments which are part of the non-enzymatic antioxidant mechanisms. In this work we focused on the antioxidant capacity of pigments from an Antarctic microorganism belonging to Pedobacter genus. This microorganism produces different types of pigments which belong to the carotenoids group. The antioxidant capacity of a mix of pigments was analyzed by three different methods: 1,1-diphenyl-2-picrylhydrazyl, ROS detection and oxygen electrode. The results obtained from these approaches indicate that the mix of pigments has a strong antioxidant capacity. The oxidative damage induced by UVB exposure to liposomes was also analyzed. Intercalated pigments within the liposomes improved its resistance to lipid peroxidation. Based on the analysis carried out along this research we conclude that the antioxidant properties of the mix of pigments protect this bacterium against oxidative damage. These properties make this mix of pigments a powerful antioxidant mixture with potential biotechnological applications.     

Fluorescence of rhodopsins and its relation to primary processes of light energy transformation

A new area of the investigation of visual and bacterial rhodopsins--fluorescence spectroscopy of the pigments is discussed. Fluorescence properties are considered in relation to photochemical transformations of the pigments at low temperatures. A number of fluorescent states of the pigments are described. It is shown that the excited states of bacteriorhodopsin and visual rhodopsin are characterized by a series of common features. The analysis of general properties of the pigments excited states allows a conclusion that the singlet excited states take part in the photoreaction. The photoreaction scheme is discussed in which structural changes of the chromophore take place already in the excited state.     

A quantitative model of the domain structure of the photosynthetic membrane

A model is presented that gives a quantitative picture of the distribution of the photosynthetic components in the photosynthetic membrane of higher plants. A salient feature of the model is that most of the pigments are located in the grana where photosystem I and II carry out linear electron transport, whereas the stroma lamellae, which harbour <20% of the pigments, carry out photosystem-I-mediated cyclic electron transport. This arrangement derives from the observation that more pigments are associated with photosystem I, which therefore captures more quanta than photosystem II. The excess pigments associated with photosystem I are thought to be located in the stroma lamellae.     

Carotene Wax Pigments in the Foraminiferan Allogromia laticollaris Arnold

SYNOPSIS. It is evident from the results obtained by UV spectroscopy and chemical analyses that the pigments of the foraminiferan Allogromia laticollaris are carotene waxes of the xanthophyll type. Since none of the pigments was found in the food organisms, one can exclude the possibility that these pigments are derived from food. The origin of the pigments is discussed.     

Melanin pigments of fungi under extreme environmental conditions (Review)

This review is dedicated to the research on the functions of melanin pigments in fungi. The participation of melanin pigments in protection from environmental factors is considered. Data on the biosynthetic pathways and types of melanin pigments in fungi are presented.     

The molecular evolution of avian ultraviolet- and violet-sensitive visual pigments

The shortwave-sensitive SWS1 class of vertebrate visual pigments range in lambda(max) from the violet (385-445 nm) to the ultraviolet (UV) (365-355 nm), with UV-sensitivity almost certainly ancestral. In birds, however, the UV-sensitive pigments present in a number of species have evolved secondarily from an avian violet-sensitive (VS) pigment. All avian VS pigments expressed in vitro to date encode Ser86 whereas Phe86 is present in all non-avian ultraviolet sensitive (UVS) pigments. In this paper, we show by site directed mutagenesis of avian VS pigments that Ser86 is required in an avian VS pigment to maintain violet-sensitivity and therefore underlies the evolution of avian VS pigments. The major mechanism for the evolution of avian UVS pigments from an ancestral avian VS pigment is undoubtedly a Ser90Cys substitution. However, Phe86, as found in the Blue-crowned trogon, will also short-wave shift the pigeon VS pigment into the UV whereas Ala86 and Cys86 which are also found in natural avian pigments do not generate short-wave shifts when substituted into the pigeon pigment. From available data on avian SWS1 pigments, it would appear that UVS pigments have evolved on at least 5 separate occasions and utilize 2 different mechanisms for the short-wave shift.     

Pathways of chemical evolution of photosynthesis

The primary metabolism of protobionts was probably based on the electron transfer reactions regulated by catalysts or photosensitizing pigments. The action of photoreceptive pigments was inevitable in the case of electron transfer leading to light energy storage in the reaction products. The primitive tetrapyrrolic pigments formed abiogenically (porphin, chlorin) as well as their more complicated biogenic analogs (chlorophylls) are capable to photosensitize electron transfer in systems, having various degree of molecular complexity. The inorganic photosensitizers (titanim dioxide, zinc oxide, etc.). being excited in near UV are able to perform the same reactions as porphyrins —electron transfer from donor to acceptor molecule (including photoreduction of viologens) or water molecule photooxidation (oxygen liberation), coupled with reduction of ferric compounds and quinones. The inorganic photosensitizers are not used in biological evolution; actually the inorganic ions entered into tetrapyrrolic cycle, forming effective photocatalysts. Inclusion of pigments into primary membranes led to elaborated coupling between pigments and enzymatic systems. The involvement of the excited pigments into the biocatalytic electron transfer chain served as prerequisite of effective function of photosynthetic organisms.     

The anti-mutagenic properties of bile pigments

Bile pigments, including bilirubin and biliverdin, are endogenous compounds belonging to the porphyrin family of molecules. In the past, bile pigments and bilirubin in particular were thought of as useless by-products of heme catabolism that can be toxic if they accumulate. However, in the past 20 years, research probing the physiological relevance of bile pigments has been mounting, with evidence to suggest bile pigments possess significant antioxidant and anti-mutagenic properties. More specifically, bile pigments are potent peroxyl radical scavengers and inhibit the mutagenic effects of a number of classes of mutagens (polycyclic aromatic hydrocarbons, heterocyclic amines, oxidants). Coincidentally, persons with elevated circulating bilirubin concentrations have a reduced prevalence of cancer and cardio-vascular disease. Despite the encouraging in vitro anti-mutagenic effects of bile pigments, relatively little research has been conducted on their inhibitory capacity in bacterial and cultured cell assays of mutation, which might link the existing in vitro and in vivo observations. This is the first review to summarise the published data and it is our hope it will stimulate further research on these potentially preventative compounds.     

Pigments with antibiotic activity from Myxococcus coralloides

A strain of Myxococcus coralloides produces pigments with antibiotic activity. The pigments are non-diffusible and become detectable at the beginning of the autolytic phase. Red pigments produced by vegetatively growing cells were extracted by acetone treatment. The crude extract when chromatographed yielded several fractions, two of which were active against certain Gram-positive bacteria. Both fractions were partial purified in thin layer chromatography and can be differentiated according to colour, polarity and absorption spectrum. Production of active pigments is increased by nicotine and inhibited by diphenylamine. The pigments are also compared with the antibiotic produced by this bacterium.     

Polychromatism of the egg shell in the domestic quail (Coturnix coturnix japonica). 6. Comparison with polychromatism in related species]

Polychromatism and pigments of five Phasianides egg-shells others than japanese quail are studied. Polychromatism modalities and pigments repartitions are species specific.     

The effect of different nitrogen sources on pigment production and sporulation of Monascus species in submerged, shaken culture.

Thirty-nine strains from the genus Monascus were cultivated aerobically to study the relation between nitrogen nutrition and sporulation and pigment production. The effects of yeast extract, nitrate, ammonium, and ammonium nitrate have been compared. During cultivation the pHs of the different media are not the same, resulting in the formation of different coloured pigments. When the source of nitrogen is yeast extract or nitrate the pH is around 6.5 and red pigments are formed, whereas with ammonium or ammonium nitrate the pH is around 2.5 and the pigments are orange. It is proposed that only the orange pigments, monascorubrin and rubropunctatin, are produced biosynthetically and that the other pigments are formed from these by chemical transformations depending on the cultural conditions. The presence of organic nitrogen is optimal for growth and unfavourable for pigment production. Reduced growth and best pigment formation occurs with the three other nitrogen sources. Nitrate stimulates conidiation and sexual reproduction, while ammonium is inhibitory. Pigment production is better when conidiation is reduced. A mechanism is proposed for the control of sporulation and pigment production.     

Cone visual pigments

Cone visual pigments are visual opsins that are present in vertebrate cone photoreceptor cells and act as photoreceptor molecules responsible for photopic vision. Like the rod visual pigment rhodopsin, which is responsible for scotopic vision, cone visual pigments contain the chromophore 11-cis-retinal, which undergoes cis–trans isomerization resulting in the induction of conformational changes of the protein moiety to form a G protein-activating state. There are multiple types of cone visual pigments with different absorption maxima, which are the molecular basis of color discrimination in animals. Cone visual pigments form a phylogenetic sister group with non-visual opsin groups such as pinopsin, VA opsin, parapinopsin and parietopsin groups. Cone visual pigments diverged into four groups with different absorption maxima, and the rhodopsin group diverged from one of the four groups of cone visual pigments. The photochemical behavior of cone visual pigments is similar to that of pinopsin but considerably different from those of other non-visual opsins. G protein activation efficiency of cone visual pigments is also comparable to that of pinopsin but higher than that of the other non-visual opsins. Recent measurements with sufficient time-resolution demonstrated that G protein activation efficiency of cone visual pigments is lower than that of rhodopsin, which is one of the molecular bases for the lower amplification of cones compared to rods. In this review, the uniqueness of cone visual pigments is shown by comparison of their molecular properties with those of non-visual opsins and rhodopsin. This article is part of a Special Issue entitled: Retinal Proteins — You can teach an old dog new tricks.     

我国植物食用色素资源开发利用评价

古代人们使用的着色剂都是天然产品,除少数矿物颜料外,主要是植物源色素。我国古代就有以红曲米作为着色剂利用的习惯;在高等植物方面,生产蓝色、黄色、绿色的颜料的高等植物种类不少,大多沿用至今。自19世纪中叶以后,人工合成色素以着色牢固、鲜艳、成本低廉等特点,迅速占领了印染、食品等许多行业,但20世纪60年代以后,许多研究表明,一般合成色素都有程度不等的毒性,特别是化学结构含偶氮型的色素有可能在人体内成为致癌物。同时,在色素合成的过程中,还有可能污染有重金属及其他有害物质。因此,合成色素越来越使人们感到不安全。从20世纪50年代的100多种人工合成色素用于食品着色,到20世纪末,已有60~70余种被禁用了,而植物食用色素在食品行业中成为主要着色剂。近年来又涌现出多种有价值的高等植物源色素,我们选择其主要一些植物种类做些介绍,供有关方面参考。     

Production of Monascus pigments as extracellular crystals by cell suspension culture

Applied Microbiology and Biotechnology - It is generally accepted that Monascus pigments are predominantly cell-bound, including both intracellular and surface-bound pigments. This long-term...     

Comparative studies on the late bleaching processes of four kinds of cone visual pigments and rod visual pigment

Visual pigments in rod and cone photoreceptor cells of vertebrate retinas are highly diversified photoreceptive proteins that consist of a protein moiety opsin and a light-absorbing chromophore 11-cis-retinal. There are four types of cone visual pigments and a single type of rod visual pigment. The reaction process of the rod visual pigment, rhodopsin, has been extensively investigated, whereas there have been few studies of cone visual pigments. Here we comprehensively investigated the reaction processes of cone visual pigments on a time scale of milliseconds to minutes, using flash photolysis equipment optimized for cone visual pigment photochemistry. We used chicken violet (L-group), chicken blue (M1-group), chicken green (M2-group), and monkey green (L-group) visual pigments as representatives of the respective groups of the phylogenetic tree of cone pigments. The S, M1, and M2 pigments showed the formation of a pH-dependent mixture of meta intermediates, similar to that formed from rhodopsin. Although monkey green (L-group) also formed a mixture of meta intermediates, pH dependency of meta intermediates was not observed. However, meta intermediates of monkey green became pH dependent when the chloride ion bound to the monkey green was replaced with a nitrate ion. These results strongly suggest that rhodopsin and S, M1, and M2 cone visual pigments share a molecular mechanism for activation, whereas the L-group pigment may have a special reaction mechanism involving the chloride-binding site.     

Six Opsins from the Butterfly Papilio glaucus: Molecular Phylogenetic Evidence for Paralogous Origins of Red-Sensitive Visual Pigments in Insects

It has been hypothesized that the UV-, blue-, and green-sensitive visual pigments of insects were present in the common ancestor of crustaceans and insects, whereas red-sensitive visual pigments evolved later as a result of convergent evolution. This hypothesis is examined with respect to the placement of six opsins from the swallowtail butterfly Papilio glaucus (PglRh1–6) in relationship to 46 other insect, crustacean, and chelicerate opsin sequences. All basal relationships established with maximum parsimony analysis except two are present in the distance and maximum likelihood analyses. In all analyses, the six P. glaucus opsins fall into three well-supported clades, comprised, respectively, of ultraviolet (UV), blue, and long-wavelength (LW) pigments, which appear to predate the radiation of the insects. Lepidopteran green- and red-sensitive visual pigments form a monophyletic clade, which lends support to the hypothesis from comparative physiological studies that red-sensitive visual pigments in insects have paralogous origins. Polymorphic amino acid sites (180, 197, 277, 285, 308), which are essential for generating the spectral diversity among the vertebrate red- and green-sensitive pigments are notably invariant in the Papilio red- and green-sensitive pigments. Other major tuning sites must be sought to explain the spectral diversification among these and other insect visual pigments. Received: 6 December 1999 / Accepted: 3 April 2000     

Spectral tuning of avian violet- and ultraviolet-sensitive visual pigments

The violet- and ultraviolet-sensitive visual pigments of birds belong to the same class of pigments as the violet-sensitive (so-called blue) pigments of mammals. However, unlike the pigments from mammals and other vertebrate taxa which, depending on species, have lambda(max) values of either around 430 nm or around 370 nm, avian pigments are found with lambda(max) values spread across this range. In this paper, we present the sequences of two pigments isolated from Humbolt penguin and pigeon with intermediate lambda(max) values of 403 and 409 nm, respectively. By comparing the amino acid sequences of these pigments with the true UV pigments of budgerigar and canary and with chicken violet with a lambda(max) value of 420 nm, we have been able to identify five amino acid sites that show a pattern of substitution between species that is consistent with differences in lambda(max). Each of these substitutions has been introduced into budgerigar cDNA and expressed in vitro in COS-7 cells. Only three resulted in spectral shifts in the regenerated pigment; two had relatively small effects and may account for the spectral shifts between penguin, pigeon, and chicken whereas one, the replacement of Ser by Cys at site 90 in the UV pigments, produced a 35 nm shortwave shift that could account for the spectral shift from 403 nm in penguin to around 370 nm in budgerigar and canary.