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1.
Xiaomin Cao Yun Tian Zhiyong Wang Yunwen Liu Cunxin Wang 《Journal of Thermal Analysis and Calorimetry》2014,117(3):1489-1495
The protein denaturation kinetic processes of a simple and a complex reaction mechanism represented by bovine serum albumin and hen egg-white lysozyme were analyzed by an iso-conversional method using differential scanning calorimetry. After differential scanning calorimetry using the iso-conversional method, the results were found to pose distinct contrasts between the two proteins. Bovine serum albumin showed an increasing peak temperature of the transition as the scan rate and protein concentration increased, whereas hen egg-white lysozyme exhibited almost constant peak temperature. The differential scanning calorimetry transition of bovine serum albumin was calorimetrically irreversible, while one part of hen egg-white lysozyme denaturation process was irreversible during which aggregation occurred and the other part was reversible. The iso-conversional method indicated that the value of bovine serum albumin apparent activation energy hardly varied with the degree of conversion, which showed that the denaturation kinetic process should conform to single reaction model. Using the master plots method, the most possible kinetic model for bovine serum albumin denaturation might be described by F n kinetic model. On the contrary, the hen egg-white lysozyme value of apparent activation energy decreased with the increase of degree of conversion. It was not a process involving the two standard reversible states, and can be described by the simple Lumry–Eyring model. The iso-conversional method provides new opportunities in exploring a simple and a complex reaction mechanism of protein denaturation. 相似文献
2.
The interactions between seven anionic azo dyes and hen egg-white lysozyme were investigated by means of visible absorption spectroscopic and lytic activity measurements. The dyes, for which no report on the interaction has appeared so far, were bound with lysozyme to different extents as a result of the differences in their chemical structures. Although most of the dyes formed 11 complex with lysozyme, two of them behaved differently. From the measurements of the absorption, lytic inhibition toward cell walls and competitive binding with substrate analogues, it was concluded that a major binding site of these dyes on lysozyme is a charged lysine residue in the vicinity of the subsitesD, E andF, and, in the case of a dye that forms 21 complex with lysozyme, and additional binding site is in the vicinity of the subsite B. 相似文献
3.
Concentration-Dependent Influence of Silver Nanoparticles on Amyloid Fibrillation Kinetics of Hen Egg-White Lysozyme
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Wei Fan Xiao-dong Chen Li-ming Liu Ning Chen Xiao-guo Zhou Zhi-hong Zhang Shi-lin Liu 《化学物理学报(中文版)》2021,34(4):393-405
Understanding the influence of nanoparticles on the formation of protein amyloid fibrillation is crucial to extend their application in related biological diagnosis and nanomedicines. In this work, Raman spectroscopy was used to probe the amyloid fibrillation of hen egg-white lysozyme in the presence of silver nanoparticles (AgNPs) at different concentrations, combined with atomic force microscopy and thioflavin T (ThT) fluorescence assays. Four representative Raman indicators were utilized to monitor transformation of the protein tertiary and secondary structures at the molecular level: the Trp doublet bands at 1340 and 1360 cm-1, the disulfide stretching vibrational peak at 507 cm-1, the N-C$\alpha$-C stretching vibration at 933 cm-1, and the amide Ⅰ band. All experimental results confirmed the concentration-dependent influence of AgNPs on the hen egg-white lysozyme amyloid fibrillation kinetics. In the presence of AgNPs at low concentration (17 μg/mL), electrostatic interaction of the nanoparticles stabilizes disulfide bonds, and protects the Trp residues from exposure to hydrophilic environment, thus leading to formation of amorphous aggregates rather than fibrils. However, with the action of AgNPs at high concentration (1700 μg/mL), the native disulfide bonds of hen egg-white lysozyme are broken to form Ag-S bonds owing to the competition of electrostatic interaction from a great deal of nanoparticles. As for providing functional surfaces for protein to interact with, AgNPs play a bridge role in direct transformation from $\alpha$-helices to organized $\beta$-sheets. The present investigation sheds light on the controversial effects of AgNPs on the kinetics of hen egg-white lysozyme amyloid fibrillation. 相似文献
4.
The solid-phase peptide synthesis of an octapeptide contained in hen egg-white lysozyme (sequence Cys (residue 64) to Gly (residue 71)) is reported. Each step of the synthesis was verified by amino acid analysis. Three main reaction products were obtained. The octapeptide (50% of the reaction products) was purified by two chromatographies on Dowex 50 × 2. The purified peptide was digested by an aminopeptidase and degradated by means of Edman' s method; this latter procedure has shown that the purified octapeptide still contained around 10% of a shorter peptide. 相似文献
5.
多壁碳纳米管固相萃取-在线提取蛋清中的溶菌酶 总被引:1,自引:1,他引:1
建立了以羧基功能化的多壁碳纳米管作为吸附剂在线提取蛋清中溶菌酶的新方法. 将多壁碳纳米管经氧化和提纯后装入固相萃取柱, 在顺序注射系统中实现对蛋清中溶菌酶的在线选择性萃取, 以碳酸盐缓冲溶液定量洗脱, 进样量为2 mL时, 富集倍率为12, 吸附率和洗脱率均为100%, 采样速率为10 h-1, 精密度为3.0%. 实验结果表明, 该方法所用试剂量少, 提取速度快, 每100 mL蛋清可提取溶菌酶0.4 g, 且溶菌酶纯度较高. 相似文献
6.
Antony V. Samrot Reddy B. Avinesh Sahaya D. Sukeetha P. Senthilkumar 《Applied biochemistry and biotechnology》2011,163(1):195-203
Polyhydroxyalkanoates (PHAs) are polymers of hydroxyalkanoate, which are accumulated by many bacteria as food storage material
under excess carbon source and limited nitrogen source. In our study, Enterobacter cloacae SU-1 isolated from the rhizospheric soil of Arachis hypogea was allowed to grow as batch culture in minimal media containing either glucose or lactose, and the pattern of PHA accumulation
by E. cloacae SU-1 was studied. E. cloacae SU-1 was found to accumulate 94% of PHA/dry weight of the organism in 8 g/l lactose-containing medium. When the monomeric
units of PHA of E. cloacae SU-1 was analyzed by gas chromatography, it was also found to accumulate medium chain length PHA 3-hydroxyoctanoate (3HO)/3-hydroxyhexanoate
(3HH) in the presence of glucose and lactose, but the ratio of these monomers differed as 11:1 and 6:1, respectively. 相似文献
7.
《Journal of Coordination Chemistry》2012,65(19):3463-3470
A new tridentate ligand, [(2-hydroxy-3,5-diiodo-benzylidene)-amino]-acetic acid (HDBA), has been synthesized from 3,5-diiodosalicylaldehyde and glycine in ethanol. A 1-D coordination polymer has been synthesized by reaction of HDBA with Cu(Ac)2 · H2O in ethanol–water. The complex was characterized by UV, IR, ESI–MS, elemental analyses, and X-ray crystallography. The central copper(II) is five-coordinate by one nitrogen and two oxygens from HDBA, one oxygen from water, and one oxygen from another HDBA. The complex was assayed for antibacterial (Bacillus subtilis, Staphylococcus aureus, Streptococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, and Enterobacter cloacae) activities by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide method. Complex 1 showed favorable antimicrobial activity with minimum inhibitory concentrations of 6.25, 6.25, 3.125, 6.25, 6.25, and 3.125 µg mL?1 against B. subtilis, S. aureus, S. faecalis, P. aeruginosa, E. coli, and E. cloacae, respectively. 相似文献
8.
Four disulfide bridges of hen egg-white lysozyme were selectively reduced to obtain its derivatives with three, two, and
zero disulfide bridges (designated as 3SS, 2SS, and 0SS lysozymes, respectively). The 3SS lysozyme maintained the native conformation
at pH 7.0 and 3.0. Even upon the reduction of two disulfide bridges, the protein conformation still remained unchanged at
pH 7.0. Upon the reduction of all four disulfide bridges, the helicity, [θ]270, and tryptophan fluorescence changed at pH 3.0 as well as at pH 7.0. The helicity of each derivative increased in a solution
of sodium dodecyl sulfate (SDS). The SDS-induced helicity of the 0SS lysozyme was lower at pH 7.0 and higher at pH 3.0 than
that of the intact lysozyme with four disulfide bridges. The helix formation appears to occur in originally nonhelical parts
in each derivative at pH 7.0. In the cases of the 2SS and 0SS lysozymes at pH 3.0, however, some of the helices appear to
be reformed also at moieties where the original helices are disrupted upon the cleavage of disulfide bridges.
Received: 17 September 2000/Accepted: 24 March 2000 相似文献
9.
Abstract— The photochemical yields for inactivation and amino acid destruction in hen and duck egg-white lysozyme are presented. Duck lysozyme II is devoid of histidine but it has two more tyrosine residues than does hen lysozyme. The data indicate that sensitized oxidation of the single histidine residue of hen lysozyme is of no significance for the inactivation of this lysozyme. The ultraviolet destruction of tryptophan and cystine residues appears to be equally related with the loss in enzymatic activity of hen lysozyme. In the case of duck lysozyme, however, the ultraviolet inactivation appears to be predominantly governed by the destruction of cystine residues. 相似文献
10.
《Chemistry & biology》1996,3(4):295-299
Background: The use of proteases to form, instead of break, peptide bonds has expanded the repertoire of techniques available for protein semisynthesis. Several groups have previously reported the use of proteases in aqueous-organic solvents to form single amide bonds within proteins, but low yields and lengthy reaction times make this an impractical approach to protein synthesis. We recently found that proteolyzed triose phosphate isomerase can be re-ligated rapidly and efficiently by subtilisin, in mixed aqueous-organic solvent systems.Results: We now report the use of subtilisin to resynthesize hen egg-white lysozyme from a mixture of its proteolyzed fragments in high yield and with rapid reaction times. This enzymatic religation can also be achieved after reduction of the four disulfide bonds present in lysozyme, with the same efficiency as that observed for the disulfide-containing proteolysis mixture.Conclusions: For egg-white lysozyme, the subtilisin religation reaction can be used to re-synthesize a proteolyzed protein even after reduction of disulfide bonds. The utility of this reaction in more generalized protein semisynthesis reactions is currently being explored. 相似文献
11.
Aysha B. Mezoughi Chiara M. Costanzo Gregor M. Parker Enas M. Behiry Alan Scott Andrew C. Wood Sarah E. Adams Richard B. Sessions E. Joel Loveridge 《Molecules (Basel, Switzerland)》2021,26(14)
Lytic transglycosylases such as Slt35 from E. coli are enzymes involved in bacterial cell wall remodelling and recycling, which represent potential targets for novel antibacterial agents. Here, we investigated a series of known glycosidase inhibitors for their ability to inhibit Slt35. While glycosidase inhibitors such as 1-deoxynojirimycin, castanospermine, thiamet G and miglitol had no effect, the phenothiazinium dye thionine acetate was found to be a weak inhibitor. IC50 values and binding constants for thionine acetate were similar for Slt35 and the hen egg white lysozyme. Molecular docking simulations suggest that thionine binds to the active site of both Slt35 and lysozyme, although it does not make direct interactions with the side-chain of the catalytic Asp and Glu residues as might be expected based on other inhibitors. Thionine acetate also increased the potency of the beta-lactam antibiotic ampicillin against a laboratory strain of E. coli. 相似文献
12.
Robert B. Cody Jun Tamura Jeffrey W. Finch Brian D. Musselman 《Journal of the American Society for Mass Spectrometry》1994,5(3):194-200
Array detection was compared with point detection for solutions of hen egg-white lysozyme, equine myoglobin, and ubiquitin analyzed by electrospray ionization with a magnetic sector mass spectrometer. The detection limits for samples analyzed by using the array detector system were at least 10 times lower than could be achieved by using a point detector on the same mass spectrometer. The minimum detectable quantity of protein corresponded to a signal-to-background ratio of approximately 2∶1 for a 500 amol/μL solution of hen egg-white lysozyme. However, the ultimate practical sample concentrations appeared to be in the 10–100 fmol/μL range for the analysis of dilute solutions of relatively pure proteins or simple mixtures. 相似文献
13.
A new deep-UV Raman spectrometer utilizing a laser source tunable between 193 and 205 nm has been designed, built, and characterized. Only selected wavelengths from this range have previously been accessible, by Raman shifting of the second, third, and fourth harmonics of the Nd:YAG fundamental in hydrogen. The apparatus was demonstrated to be a useful tool for characterizing hen egg white lysozyme structural rearrangements at various stages of fibril formation. High-quality deep-UV resonance Raman spectra were obtained for both a protein solution and a highly-scattering gelatinous phase formed by fibrillogenic species. In addition to amide bands, strong contribution of 12
and ring-C phenylalanine vibrational modes was observed at excitation wavelengths below 200 nm. Remarkably, the Raman cross-section of these modes revealed dramatic change of lysozyme in response to heat denaturation and fibril formation. These results indicate that phenylalanine could serve as a new deep-UV Raman probe of protein structure. 相似文献
14.
Hideo Tanaka Tomoharu Ebata Isamu Kuwahara Masaru Matsuo James C. Ogbonna 《Applied biochemistry and biotechnology》1999,80(1):51-64
Development and application of a system for real-time quantitative assessment of individual cell activities in a mixed culture
system was investigated. This was based on a concept that the activities of individual cells in a mixed culture can be assessed
if the cells are physically separated (in separate compartments) in a vessel while the culture conditions, including the broth
components, are maintained the same in all the compartments during the cultivation. On this basis, three different apparatus
(M-1, M-2, and M-3) were constructed using various types of membranes. In terms of mass transfer characteristics and membrane
fouling, the M-3 apparatus was the most effective system for analysis of mixed cultures at high cell densities. With the M-3
apparatus, the interrelationships between two alcohol-producing strains (Saccharomyces cerevisiae and Zymomonas mobilis) under anaerobic and aerobic conditions were studied. Under anaerobic condition, except for possible competition for nutrients,
there were no significant effects of the activities of one microorganism on the other. However, under aerobic condition, amensalism
was observed because acetaldehyde that was produced by Z. mobilis inhibited the growth of S. cerevisiae. 相似文献
15.
《Analytical letters》2012,45(1):58-67
Abstract A new method for the rapid identification and quantification of Pseudomonas aeruginosa using multichannel series piezoelectric quartz crystal (MSPQC) was proposed. The identification of P. aeruginosa was based on the development of acetamide broth, which can selective culture P. aeruginosa and performed perfectly in MSPQC. The quantitative detection of P. aeruginosa was based on the fact that the frequency detection time (FDT) detected by MSPQC in developed medium had a linear relationship with the logarithm of its initial concentration in the range of 10–108 colony ? forming units (cfu) ml–1 (R=?0.984). The detection limit was 10 cfu ml–1. 相似文献
16.
Dara Dastan Peyman Salehi Atousa Aliahmadi Ahmad Reza Gohari Hossein Maroofi Afshan Ardalan 《Natural product research》2016,30(24):2747-2753
In this study, the antibacterial activity of disesquiterpene coumarin and sesquiterpene coumarins obtained from Ferula pseudalliacea roots was evaluated by determination of minimum inhibitory concentration using the broth micro-dilution method against seven pathogenic bacterial strains (Staphylococcus aureus ATCC 25,923, vancomycin resistant clinical strain of Enterococcus faecium, Bacillus cereus PTCC 1015, Escherichia coli ATCC 25,922, Pseudomonas aeruginosa PTCC 1430, clinical strain of Klebsiella pneumoniae and a clinical strain of Helicobacter pylori). The overall inhibitory activities of the compounds were higher against Gram positive tested bacteria. Sanandajin and ethyl galbanate demonstrated significant activity against H. pylori strain, as well as S. aureus strain in concentration of 64 μg/ml. Methyl galbanate inhibited vancomycin resistant strain of E. faecium in concentration of 64 μg/ml. The results of the present investigation indicated that disesquiterpene and sesquiterpene coumarins isolated from F. pseudalliacea root extract can be considered as potent antibacterial agents for pharmaceutical and food industries. 相似文献
17.
Antoine Rousseau Dr. Sylvie Armand Prof. Sylvain Cottaz Dr. Sébastien Fort 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(70):17637-17646
Chitin and peptidoglycan fragments are well recognized as pathogen associated molecular patterns (PAMPs). Long-chain oligosaccharides of β(1→4)-linked N-acetyl-D-glucosamine (GlcNAc) units indeed activate plants and mammals innate immune system. However, the mechanisms underlying PAMPs perception by lysine motif (LysM) domain receptors remain largely unknown because of insufficient availability of high-affinity molecular probes. Here, we report a two-enzyme cascade to synthesize long-chain β(1→4)-linked GlcNAc oligomers. Expression of the D52S mutant of hen egg-white lysozyme (HEWL) in Pichia pastoris at 52 mg L−1 provided a new glycosynthase catalyzing efficient polymerization of α-chitintriosyl fluoride. Selective N-deacetylation at the non-reducing unit of the glycosyl fluoride donor by Sinorhizobium meliloti NodB chitin-N-deacetylase abolished its ability to be polymerized by the glycosynthase but not to be transferred onto an acceptor. Using NodB and D52S HEWL in a one-pot cascade reaction allowed the synthesis on a milligram scale of chitin hexa-, hepta- and octasaccharides with yields up to 65 % and a perfect control over their size. 相似文献
18.
C. Sacco M. Bellumori F. Santomauro R. Donato R. Capei M. Innocenti 《Natural product research》2015,29(16):1537-1544
In this study, the aim was to evaluate the antimicrobial action of the non-volatile phenols of rosemary leaves against two Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and two Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis). Three extracts with different phenolic compositions were tested. By the agar disc diffusion method, Gram-positive bacteria were more sensitive to the extracts, and S. epidermidis showed the highest inhibition zones. Overall, all the extracts tested by the broth dilution method showed higher activity than results from the agar disc diffusion method. The minimal bactericidal concentration values indicated that E. coli was the most susceptible strain. This study demonstrated that the flavonoidic fraction of rosemary leaves does not play a crucial role as antimicrobial agents against these microorganisms. The most active extract was characterised by the highest amount of non-volatile terpenoidic compounds. 相似文献
19.
Katia Liburdi Raffaello Straniero Ilaria Benucci Anna Maria Vittoria Garzillo Marco Esti 《Applied biochemistry and biotechnology》2012,166(7):1736-1746
In order to use lysozyme as an anti-microbial agent during the winemaking process, hen egg-white lysozyme (LYZ) was covalently
immobilized on two different micro-size magnetic particles (tosyl-activated and carboxylated, TSA and CA, respectively). A
cell suspension of Oenococcus oeni, an oenological strain involved in the winemaking process, was utilized as LYZ substrate. Both a kinetic study and a study
of the stability of free and immobilized LYZ were performed in McIlvane buffer at pH 3.2, that is the average minimum pH value
in wine. The activity and kinetic parameters measured for the free LYZ at pH 3.2 are lower than those reported at the optimum
pH (4.5); however the residual activity at pH 3.2 is sufficient to be of interest for further immobilization and applications
in winemaking. All kinetic parameters of both biocatalysts (LYZ-CA and LYZ-TSA) are altered after immobilization, probably
due to the structural modifications in the active site caused by covalent attachment to the supports. The half-life calculated
at 25 °C was 39 h for free LYZ, while it increased to 280 and 134 h for LYZ-TSA and LYZ-CA, respectively. This result indicates
that immobilization improves the enzyme stability and that LYZ can be utilized in wine applications in its immobilized forms.
In addition, LYZ-TSA seems to be the best biocatalyst for further applications in winemaking. 相似文献
20.
Enterobacter cloacae is a highly pathogenic Gram-negative proteobacterium which is responsible for a wide array of infections. In the present study, the fermentation culture of E. cloacae has yielded one new oxolane compound, Rimboxo (1) in addition to three known compounds, i.e. Maculosine (2), phenylacetic acid (3) and methyl myristate (4). These compounds were isolated and characterised using extensive chromatographic and spectroscopic methods, and were subjected to cytotoxicity evaluations. 相似文献