Raman spectroscopy and WAXS method as a tool for analysing ion-exchange properties of alginate hydrogels

Hydrogels are cross-linked three-dimensional macromolecular networks that contain a large fraction of water within their structure. One of the most important properties of alginate hydrogels, leading to their broad versatility, is their ability for controlled uptake, release and retention of molecules. This ability, in turn, is due to specific interactions of the macromolecular network with the diffusing or retained molecule. Raman spectroscopy has been employed to characterize the diffusion properties of solutes in hydrogels. Besides their application in the food sector, they are used in many biomedical, pharmaceutical and technical areas; for example, as a natural tissue or drug carriers. In the latter case, controlled release of drugs from a wound dressing is of particular interest-or ion exchange between the drug and the structure of the dressing. Raman active vibrations were used to show the areas responsible for the penetration of the model azo-dyes (based on non-genotoxic benzidine analogs) within Ca-alginate/carboxymethylcellulose Medisorb A wound dressing. In this case, the intensity of the stretching bands was used to obtain the concentration profiles of the model dye in alginate/carboxymethylcellulose gel (Medisorb A). The characteristic band at 1511 cm(-1) indicates that new band positions were observed following dye adsorption on wound dressing. The Raman spectra of alginate immersed for different times in Ringer's solution reveal peak shifts. Differences in peak shapes and the appearance of new bands are observed as the sodium content increased. Raman spectra give direct information on the exchange process. There are also new peaks appearing at 1034-1016 and 850 cm(-1) regions in the spectra after the release studies. This could, therefore, correspond to a partial bonding between sodium and oxygen atoms (the guluronic units originate a band at approximately 1025 cm(-1)). The aim of the examination in this paper also was to investigate the crystallinity index of Medisorb A wound dressing dyed (or undyed) and Medisorb A wound dressing after the release process in Ringer's solution (the crystallinity index is about 65%). In WAXS curves we can observed additional peaks (2theta at 32 degrees and 45 degrees ).     

Deciphering the finger Prints of Brain Cancer Astrocytoma in comparison to Astrocytes by using near infrared Raman Spectroscopy

To explore the biochemical differences between brain cancer cells Astrocytoma and normal cells Astrocyte, we investigated the Raman spectra of single cell from these two cell types and analyzed the difference in spectra and intensity. Raman spectrum shows the banding pattern of different compounds as detected by the laser. Raman intensity measures the intensity of these individual bands. The Raman spectra of brain cancer cells was similar to those of normal cells, but the Raman intensity of cancer cells was much higher than that of normal cells. The Raman spectra of brain cancer Astrocytoma shows that the structural changes of cancer cells happen so that many biological functions of these cells are lost. The results indicate that Raman spectra can offer the experimental basis for the cancer diagnosis and treatment.     

63/65Cu and 1/2H2O isotope shifts in the low-temperature resonance Raman spectrum of fungal laccase

Resonance Raman spectra are reported for the type 1 Cu site of fungal laccase at 295 and 77 K. The low-temperature spectra show enhanced resolution and reveal several weak bands not previously observed, as well as overtone and combination bands associated with the strong approximately equal to 400 cm-1 fundamentals. A novel low-temperature Raman difference technique has been used to obtain 63/65Cu and 1/2H2O isotope shifts. The strong band at 428 cm-1, and the moderate intensity bands at 408 and 387 cm-1 show small (under 0.6 cm-1 63/65Cu isotope shifts. The aggregate shift is substantially less than that expected for an isolated Cu-S(cys) stretch, implying a high degree of mixing of this coordinate with internal modes of the ligands. 1/2H2O shifts of 1.1 and approximately equal to 0.3 cm-1 are observed for the 387 and 428 cm-1 bands. The isotope shift patterns are quite similar for fungal and tree laccase, as are the frequencies of the dominant bands, indicating that the large differences in relative intensity are primarily associated with differences in the excited state potential. The frequency and isotope shift patterns are appreciably different, however, from those observed for azurin and stellacyanin. In contrast to the other 'blue' Cu proteins, fungal laccase shows no moderate intensity band near 270 cm-1 which can be associated with Cu-imidazole stretching; weak features are seen in this region, but the intensities are too low to determine their 1/2H2O sensitivity. The C-S stretching mode of fungal laccase is identified at 737 cm-1, shifting to 741 cm-1 at 77 K. It is about 10 cm-1 lower than for most 'blue' Cu proteins, and the difference is suggested to reflect smaller kinematic coupling between the C-S and Cu-S coordinates, associated with a smaller Cu-S-C angle. Combination modes of the approx. 400 cm-1 fundamentals are substantially stronger, relative to the overtones, than is predicted by first-order scattering theory, implying changes in the excited-state normal modes (Dushinsky effect) associated with force constant alterations.     

Numerical simulations of Raman spectra of guanine-cytosine Watson-Crick and protonated Hoogsteen base pairs

Large changes in the Raman spectra of calf thymus DNA are observed upon lowering the pH. In order to gain a better insight into these effects, several simulations of the Raman spectra of the guanine-cytosine (GC) Watson-Crick and Hoogsteen base pairs are performed. By comparing the Raman bands of GC base pairs in calf thymus DNA at high and low pH with the theoretical simulations of GC base pairs, it is found that the intensity changes in the theoretical bands located between 400 and 1000 cm(-1) are small compared to the experimental ones. The behavior of the cytosine band at 1257 cm(-1) upon lowering the pH is not reproduced in the GC theoretical spectra. The bands located above 1300 cm(-1) in the theoretical spectra display intensity changes that are similar to those found for GC base pairs in calf thymus DNA spectra.     

Resonance Raman spectra of beta-carotene in native and modified low-density lipoprotein

Low-density lipoproteins isolated between density 1.02 and 1.063 g/cm3 from normal fasting human plasma, show strong resonance Raman spectra due to the presence of beta-carotene. Three intense bands, at 1010, 1160 and 1530 cm-1, are assigned to the stretching vibrations of -C-CH3, = C-C = and -C = C- bonds, respectively, of beta-carotene. High-resolution spectra of the 1500-1600 cm-1 region reveal multiple features, suggesting the coexistence of several structural populations of beta-carotene. The modifications of lipoproteins with pH and temperature (30 degrees-42 degrees) change the resonance Raman spectra of beta-carotene. The specific binding of LDL at pH 7.0 by fibroblast cells is suppressed. Our experiments thus suggest that physical and chemical perturbations of plasma lipoproteins modify the lipid-protein interactions and thereby alter the configurational distribution of beta-carotene molecules within these particles.     

Artemether-lumefantrine to treat malaria in pregnancy is associated with reduced placental haemozoin deposition compared to quinine in a randomized controlled trial

ABSTRACT: BACKGROUND: Data on efficacy of artemisinin-based combination therapy (ACT) to treat Plasmodium falciparum during pregnancy in sub-Saharan Africa is scarce. A recent open label, randomized controlled trial in Mbarara, Uganda demonstrated that artemether-lumefantrine (AL) is not inferior to quinine to treat uncomplicated malaria in pregnancy. Haemozoin can persist in the placenta following clearance of parasites, however there is no data whether ACT can influence the amount of haemozoin or the dynamics of haemozoin clearance. METHODS: Women attending antenatal clinics with weekly screening and positive blood smears by microscopy were eligible to participate in the trial and were followed to delivery. Placental haemozoin deposition and inflammation were assessed by histology. To determine whether AL was associated with increased haemozoin clearance, population haemozoin clearance curves were calculated based on the longitudinal data. RESULTS: Of 152 women enrolled in each arm, there were 97 and 98 placental biopsies obtained in the AL and quinine arms, respectively. AL was associated with decreased rates of moderate to high grade haemozoin deposition (13.3% versus 25.8%), which remained significant after correcting for gravidity, time of infection, re-infection, and parasitaemia. The amount of haemozoin proportionately decreased with the duration of time between treatment and delivery and this decline was greater in the AL arm. Haemozoin was not detected in one third of biopsies and the prevalence of inflammation was low, reflecting the efficacy of antenatal care with early detection and prompt treatment of malaria. CONCLUSIONS: Placental haemozoin deposition was decreased in the AL arm demonstrating a relationship between pharmacological properties of drug to treat antenatal malaria and placental pathology at delivery. Histology may be considered an informative outcome for clinical trials to evaluate malaria control in pregnancy. Trial registration REGISTRY: http://clinicaltrials.gov/ct2/show/NCT00495508.     

Characteristics and variations of B-type DNA conformations in solution: a quantitative analysis of Raman band intensities of eight DNAs

Raman spectra were obtained from four bacterial DNAs varying in GC content and four periodic DNA polymers in 0.1 M NaCl at 25 degrees C. A curve fitting procedure was employed to quantify and compare Raman band characteristics (peak location, height, and width) from 400 to 1600 cm-1. This procedure enabled us to determine the minimum number of Raman bands in regions with overlapping peaks. Quantitative comparison of the Raman bands of the eight DNAs provided several new results. All of the DNAs examined required bands near 809 (+/- 7) and 835 (+/- 5) cm-1 to accurately reproduce the experimental spectra. Since bands at these frequencies are associated with A-family and B-family conformations, respectively, this result indicates that all DNAs in solution have a mixture of conformations on the time scale of the Raman scattering process. Band characteristics in the 800-850-cm-1 region exhibited some dependence on CG content and base pair sequence. As previously noted by Thomas and Peticolas [Thomas, G. A., & Peticolas, W. L. (1983) J. Am. Chem. Soc. 105, 993], the poly[d(A)].poly[d(T)] spectra were qualitatively distinct in this region. The A-family band is clearly observed at 816 cm-1. The intensity of this band and that of the B-family band at 841 cm-1 were similar, however, to intensities in the natural DNA spectra. Three bands at 811, 823, and 841 cm-1 were required to reproduce the 800-850-cm-1 region of the poly[d(A-T)].poly[d(A-T)] spectra. This may indicate the presence of three backbone conformations in this DNA polymer. Analysis of intensity vs. GC content for 42 Raman bands confirmed previous assignments of base and backbone vibrations and provided additional information on a number of bands.     

Carotenoids as a Raman-active probes of erythrocyte membrane structure.

1. Erythrocyte ghosts exhibit resonance-enhanced Raman bands at 1530 cm(-1) and 1165 cm(-1) attributable to v(-C=C-) and v(=C-C=), respectively, of the conjugated polyene chains in carotenoids. In lipid extract of ghosts, these resonance-enhanced bands lie at 1527 and 1158 cm(-1). The spectra indicate the presence of membrane-bound beta-carotene. 2. The resonance-enhanced Raman spectrum of beta-carotene in lecithin liposomes is identical to that obtained with hexane or chloroform solutions. 3. Increasing proportions of cholesterol in cholesterol-lecithin liposomes up to a cholesterol: phospholipid molar ratio of 0.8-0.9 drastically decreases the intensity of both resonance-enhanced bands. 4. In ghosts the carotenoid bands respond to membrane perturbations. Trypsinization, lysolecithin treatment and reduction of pH increase the intensities of the 1530 and 1165 cm(-1) bands. In contrast, a decrease in the intensity of both bands follows equilibration of ghosts for 15 min at approx. 50 degrees C or addition of (0.1%) sodium dodecyl sulfate. 5. We suggest that perturbants known to change lipid-protein interactions in erythrocyte membranes modify the microenvironment and/or configuration of the membrane-bound carotenoid.     

Expression of the plasmodial pfmdr1 gene in mammalian cells is associated with increased susceptibility to chloroquine.

Chloroquine (CQ)-resistant (CQR) Plasmodium falciparum malaria parasites show a strong decrease in CQ accumulation in comparison with chloroquine-sensitive parasites. Controversy exists over the role of the plasmodial pfmdr1 gene in the CQR phenotype. pfmdr1 is a member of the superfamily of ATP-binding cassette transporters. Other members of this family are the mammalian multidrug resistance genes and the CFTR gene. We have expressed the pfmdr1-encoded protein, Pgh1, in CHO cells and Xenopus oocytes. CHO cells expressing the Pgh1 protein demonstrated an increased, verapamil-insensitive susceptibility to CQ. Conversely, no increase in drug susceptibility to primaquine, quinine, adriamycin, or colchicine was observed in Pgh1-expressing cells. CQ uptake experiments revealed an increased, ATP-dependent accumulation of CQ in Pgh1-expressing cells over the level in nonexpressing control cells. The increased CQ accumulation in Pgh1-expressing cells coincided with an enhanced in vivo inhibition of lysosomal alpha-galactosidase by CQ. CHO cells expressing Pgh1 carrying two of the CQR-associated Pgh1 amino acid changes (S1034C and N1042D) did not display an increased CQ sensitivity. Immunofluorescence experiments revealed an intracellular localization of both mutant and wild-type forms of Pgh1. We conclude from our results that wild-type Pgh1 protein can mediate an increased intracellular accumulation of CQ and that this function is impaired in CQR-associated mutant forms of the protein. We speculate that the Pgh1 protein plays an important role in CQ import in CQ-sensitive malaria parasites.     

The presence of two modes of binding to calf thymus DNA by metal-free bleomycin: a low frequency Raman study

Double-stranded DNA is targeted by bleomycin in cancer cells and ambiguity exists as to its mode of DNA binding. A conventional Raman study was performed on drug/DNA complexes in which the low frequency spectral region (560-930 cm(-1)) was examined at two temperatures (19 and 30 degrees C). At 30 degrees C, a global Raman hypochromism was observed consistent with partial intercalation of the bithiazole moiety. At 19 degrees C, Raman hypochromism (increased base pair stacking) was detected for bands associated with GC base pairs while Raman hyperchromism (base pair destacking) was evident for bands associated with AT base pairs. These results suggest that intercalation of the bithiazole moiety occurs with greater disruption of the more efficiently stacked AT base pairs at the lower temperature. Evidence for minor groove binding was indicated by an increase in the population of bands corresponding to C3' endo sugar conformations resulting from drug induced local desolvation of the DNA polymer.     

Chloroquine inhibits cell growth and induces cell death in A549 lung cancer cells

To investigate the effects of chloroquine diphosphate (CQ) on lung cancer cell growth, we treated A549 cells, a lung cancer cell line, with the drug at various concentrations (0.25-128 microM) for 24-72 h. The results showed that, at lower concentrations (from 0.25 to 32 microM), CQ inhibited the growth of A549 cells and, at the same time, it induced vacuolation with increased volume of acidic compartments (VAC). On the other hand, at higher concentrations (64-128 microM), CQ induced apoptosis at 24 h, while its effect of inducing vacuolation declined. The lactate dehydrogenase (LDH) assay showed that with the treatment of CQ 32-64 microM for 72 h or 128 microM for 48 h, CQ induced necrosis of A549 cells. To understand the possible mechanism by which CQ acts in A549 cells, we further incubated the cells with this drug at the concentrations of 32 or 128 microM in the presence of D609, a specific inhibitor of phosphatidylcholine-specific phospholipase C (PC-PLC). The results showed that D609 (50 microM) could inhibit the effects of CQ 32 microM on the viability and VAC, but it could not change the effects of CQ 128 microM on the same. Our data suggested that CQ inhibited A549 lung cancer cell growth at lower concentrations by increasing the volume of lysosomes and that PC-PLC might be involved in this process. The data also indicated that, at higher concentrations, CQ induced apoptosis and necrosis, but at this time its ability to increase the volume of lysosome gradually declined, and PC-PLC might not be implicated in the process.     

Resonance Raman microspectroscopic characterization of eosinophil peroxidase in human eosinophilic granulocytes.

A resonance Raman microspectroscopic study is presented of eosinophil peroxidase (EPO) in human eosinophilic granulocytes. Experiments were carried out at the single cell level with laser excitation in Soret-, Qv-, and charge transfer absorption bands of the active site heme of the enzyme. The Raman signal obtained from the cells was almost exclusively due to EPO. Methods were developed to determine depolarization ratios and excitation profiles of Raman bands of EPO in situ. A number of Raman band assignments based on earlier experiments with isolated EPO have been revised. The results show that in agreement with literature on isolated eosinophil peroxidase, the prosthetic group of the enzyme in the (unactivated) cells is a high spin, 6-coordinated, ferric protoporphyrin IX. The core size of the heme is about 2.04 A. The proximal and distal axial ligands are most likely a histidine with the strong imidazolate character typical for peroxidases, and a weakly bound water molecule, respectively. The data furthermore indicate that the central iron is displaced from the plane of the heme ring. The unusual low wavenumber Raman spectrum of EPO, strongly resembling that of lactoperoxidase, intestinal peroxidase and myeloperoxidase, suggests that these mammalian peroxidases are closely related, and characterized by, as yet unspecified, interactions between the peripheral substituents and the protein, different from those found in other protoheme proteins.     

Theories on malarial pigment formation and quinoline action

Haeme metabolism remains a vulnerable problem for the intraerythrocytic Plasmodium which catabolises haemoglobin as a source of amino acids in an acidic, oxygen-rich lysosome-like digestive vacuole. Haeme monomer, capable of generating oxygen radicals, transforms into an inert crystal named malarial pigment or haemozoin by forming unique dimers that then crystalise. Laveran first described pigmented bodies in humans to define a protozoan as the aetiologic agent of malaria. The trail of malaria pigment enabled Ross to implicate the mosquito in the life cycle of Plasmodium. In 1991, Slater and Cerami postulated a unique iron-carboxylate bond between two haemes in haemozoin crystals based on infrared and X-ray spectroscopy data. Additionally, parasite extracts were shown to possess a 'haeme polymerase' enzymatic activity as the process of crystal formation was then termed. Importantly, the quinolines, such as choloroquine, inhibit haemozoin formation. A Plasmodium falciparum derived histidine-rich protein II, which binds haeme and initiates haemozoin formation, is present in the digestive vacuole. Pfhistidine-rich protein II and Pfhistidine-rich protein III are sufficient, but not necessary for haemozoin formation as a laboratory clone lacking both still makes the haeme crystals. The reduvid bug, and the Schistosoma and Haemoproteus genera also make haemozoin. Recently, Bohle and coworkers used X-ray diffraction to document the iron-carboxylate bond in intact desiccated parasites and to show that a Fe1-O41 head to tail haeme dimer is the unit building block of haemozoin. The role of the Plasmodium histidine-rich protein family members, lipids or potential novel proteins in the exact molecular assembly of the large molecular weight haeme crystals in the protein rich digestive vacuole needs to be solved. Accurate experimental determination of the role of haemozoin formation and inhibition as the target of chloroquine is fundamental to determination of the mechanism of quinoline drug action and resistance. The enhanced understanding of the biosynthetic pathway leading to haemozoin formation using functional proteomic tools and the mechanisms through which existing antimalarial drugs affect Plasmodium haeme chemistry will help design improved chaemotherapeutic agents.     

1H-NMR effects in chloroquine-biopolymer binding interactions.

Chloroquine (CQ), an antimalarial and anti-inflammatory drug, is known to concentrate within lysosomes. 1H-NMR studies were conducted using the resonances of CQ itself during binding interactions with various polymers and proteins including lysosome fractions isolated from rodent livers by tritosome technique. Albumin, butyrylcholinesterase, and high molecular weight DNA interact with CQ, producing marked line-width changes that correlate with effective molecular weight. Triton WR-1339 and sucrose, probable contaminants of the lysosomal materials isolated, produced essentially no effect beyond a viscosity component. Lysosomal matrix and membrane fractions exhibited relatively weak interactions, membranes being the more tenacious toward CQ. Estimated binding constants are too small to permit explanation of CQ uptake in terms of protein affinity. The evidence is more consistent with a proton-pump trapping model proposed by de Duve et al.     

Demonstration by ultraviolet resonance Raman spectroscopy of differences in DNA organization and interactions in filamentous viruses Pf1 and fd

Pf1, a class II filamentous virus, has been investigated by ultraviolet resonance Raman (UVRR) spectroscopy with excitation wavelengths of 257, 244, 238, and 229 nm. The 257-nm UVRR spectrum is rich in Raman bands of the packaged single-stranded DNA (ssDNA) genome, despite the low DNA mass (6%) of the virion. Conversely, the 229-nm UVRR spectrum is dominated by tyrosines (Tyr 25 and Tyr 40) of the 46-residue alpha-helical coat subunit. UVRR spectra excited at 244 and 238 nm exhibit Raman bands diagnostic of both viral DNA and coat protein tyrosines. Raman markers of packaged Pf1 DNA contrast sharply with those of the DNA packaged in the class I filamentous virus fd [Wen, Z. Q., Overman, S. A., and Thomas, G. J., Jr. (1997) Biochemistry 36, 7810-7820]. Interestingly, deoxynucleotides of Pf1 DNA exhibit sugars in the C2'-endo/anti conformation and bases that are largely unstacked, compared with C3'-endo/anti conformers and very strong base stacking in fd DNA; hydrogen-bonding interactions of thymine carbonyls are also different in Pf1 and fd. On the other hand, coat protein tyrosines of Pf1 exhibit Raman markers of ring environment identical to those of fd, including an anomalous singlet at 853 cm-1 in lieu of the canonical Fermi doublet (850/830 cm-1) found in globular proteins. The results indicate markedly different modes of organization of ssDNA in Pf1 and fd virions, despite similar environments for coat protein tyrosines, and suggest strong hydrogen-bonding interactions between DNA bases and coat subunits of Pf1 but not between those of fd. We propose that structural relationships between the protein coat and encapsidated ssDNA genome are also fundamentally different in the two assemblies.     

Multiple transporters associated with malaria parasite responses to chloroquine and quinine

Mutations and/or overexpression of various transporters are known to confer drug resistance in a variety of organisms. In the malaria parasite Plasmodium falciparum, a homologue of P-glycoprotein, PfMDR1, has been implicated in responses to chloroquine (CQ), quinine (QN) and other drugs, and a putative transporter, PfCRT, was recently demonstrated to be the key molecule in CQ resistance. However, other unknown molecules are probably involved, as different parasite clones carrying the same pfcrt and pfmdr1 alleles show a wide range of quantitative responses to CQ and QN. Such molecules may contribute to increasing incidences of QN treatment failure, the molecular basis of which is not understood. To identify additional genes involved in parasite CQ and QN responses, we assayed the in vitro susceptibilities of 97 culture-adapted cloned isolates to CQ and QN and searched for single nucleotide polymorphisms (SNPs) in DNA encoding 49 putative transporters (total 113 kb) and in 39 housekeeping genes that acted as negative controls. SNPs in 11 of the putative transporter genes, including pfcrt and pfmdr1, showed significant associations with decreased sensitivity to CQ and/or QN in P. falciparum. Significant linkage disequilibria within and between these genes were also detected, suggesting interactions among the transporter genes. This study provides specific leads for better understanding of complex drug resistances in malaria parasites.     

The potentiating action of tetrandrine in combination with chloroquine or qinghaosu against chloroquine-sensitive and resistant falciparum malaria

Using chloroquine-sensitive (CS) and chloroquine-resistant (CR) strains of Plasmodium falciparum in vitro, interactions between tetrandrine (TT) and either chloroquine (CQ) or qinghaosu (QHS, artemisinin) were assessed using isobolograms. Sums of the fractional inhibitory concentration for the combination of the two drugs are less than one and therefore, we can conclude that in vitro TT and CQ or QHS act synergistically against CS and CR falciparum malaria. Remarkably, using CR malaria, TT can lower the IC50 dose of CQ as much as 40 fold. These drug combinations may impair the advantage that the development of CQ resistance conveys on the parasite.     

Changes in Raman vibrational bands of calf thymus DNA during the B-to-A transition

The B -to-A conformational transition of calf thymus DNA fibers was followed employing Raman spectroscopy. The transition was induced by soaking DNA fibers in water/ethanol mixtures increasing from 60 to 85% ethanol (v/v). Intensity changes of 17 Raman vibrational bands were quantified in the region from 400 to 860 cm^?1. Two bands at 500 and 784 cm^?1 were employed as internal standards. These bands do not appear to change in intensity with ethanol concentration. Large intensity changes relative to these two bands are observed between 70 and 74% ethanol for backbone vibrations at 708, 808, and 835 cm^?1, and base vibrations at 682, 730, and 750 cm^?1. These results indicate that a highly cooperative conformational change takes place between different portions of DNA in the B -to-A transition. Relative intensity changes preceding the onset of the major transition are observed in only two bands; at 835 cm^?1, assigned to a ribose–phosphate vibration, and at 750 cm^?1, assigned to thymine. The implications of these pretransition changes are discussed.     

一种酵母细胞生长现象的实时单细胞拉曼光谱观察

用拉曼镊子观察单个即发活性干酵母(Saccharomy cescerevisiae)细胞在2.0%葡萄糖溶液中的活化过程,收集其拉曼光谱。结果发现,在某一批次的产品中,酵母细胞的1364cm-1峰强度随着细胞的活化而显著增加,531cm-1、652cm-1、1053cm-1等源自葡萄糖或葡萄糖基的信号峰也会随细胞的生长而增强,随后增强的还有1432cm-1、1448cm-1、1561cm-1等源自脂类物质的峰,而源自蛋白质及脂类的1000cm-1、1445cm-1、1655cm-1等峰的信号强度基本不变,酵母细胞代谢活跃的标志峰1603cm-1也基本不变。该批次产品中,10次实验有7次观察到上述现象,而在别的批次产品中并没有观察到该现象。用单细胞拉曼光谱实时记录了这一特殊的生长现象。     

毛姜花油细胞原位拉曼光谱研究

为避免复杂的样品的制备及提取过程,最大限度避免精油活性成分变化,常温下,用拉曼光谱原位分析毛姜花油细胞中精油。样品切片后置于共聚焦显微拉曼光谱仪下,用10倍物镜可观察到油细胞。油细胞精油的拉曼光谱与1,8-桉油精拉曼光谱非常相似。以毛姜花油细胞/1,8-桉油精的拉曼峰为序,较强峰出现在2928/2 921、647/652 cm~(-1),次强峰出现在540/545、808/813、915/920、926/930、1 012/1 016、1 075/1 080、1 270/1273、1 427/1 432 cm~(-1)。在油细胞中出现的强峰、次强峰与1,8-桉油精的拉曼峰一致,说明毛姜花油细胞中油的主要成分为1,8-桉油精。毛姜花油细胞的25条拉曼峰都与1,8-桉油精的拉曼峰有很好的对应关系。