Studies of Site Specific DNA Binding of Small Peptides by Competitive Assays with Hoechst 33258

With a view to finding out precisely how small peptides recognize a particular binding site of DNA, we have accomplished DNA binding studies of two peptides, H-Tyr-Arg-OH (YR) and H-Gly-Gly-His-OH (GGH) by using measurements in comparison with the binding between DNA and Hoechst 33258. The inhibition mode by YR and GGH to DNA binding of Hoechst 33258 was analyzed by Lineweaver-Burk plot which shows the plot of typical competitive inhibition at concentration of Hoechst 33258 from 3.66 ( 10-9 mol / L to 1.09 ( 10-8 mol / L. And it is concluded that YR binds to DNA in its minor groove (AT rich regions) with a binding constant K = 1.02 ( 108 (mol / L)-1. The GGH(s specificity is reduced at high concentration because it can also bind GC base pair.

Peptide nucleic acid (PNA) binding-mediated gene regulation

Peptide nucleic acids (PNAs) are synthetic oligonucleotides with chemically modified backbones. PNAs can bind to both DNA and RNA targets in a sequence-specific manner to form PNA/DNA and PNA/RNA duplex structures. When bound to double-stranded DNA (dsDNA) targets, the PNA molecule replaces one DNA strand in the duplex by strand invasion to form a PNA/DNA/PNA [or (PNA)2/DNA] triplex structure and the displaced DNA strand exists as a singlestranded D-loop. PNA has been used in many studies as research tools for gene regulation and gene targeting. The Dloops generated from the PNA binding have also been demonstrated for its potential in initiating transcription and inducing gene expression. PNA provides a powerful tool to study the mechanism of transcription and an innovative strategy to regulate target gene expression. An understanding of the PNA-mediated gene regulation will have important clinical implications in treatment of many human diseases including genetic, cancerous, and age-related diseases.

Cyclic heptapeptides with metal binding properties isolated from the fungus Cadophora malorum from Antarctic soil

The Antarctic fungus Cadophora malorum produces previously undescribed cyclic heptapeptides(cadophorin A and B)containing an anthranilic acid residue.The planar structure of these peptides was determined by high-resolution mass spectrometry combined with extensive 1D and 2D NMR spectroscopy.The absolute configuration of the amino acids was determined by Marfey’s method,with HPLC analysis of FDVA(Nα-(2,4-dinitro-5-fluorphenyl)-l-valinamide)derivatives making use of a PFP column.Remarkably,cadophorin 2 possesses both the uncommon d-Ile and d-allo-Ile in its structure.The peptides have metal binding properties as shown by LCMS with post column addition of metal salt solutions.These results were supported by DFT calculations.

Photo-induced crosslinked and anti-PD-L1 peptide incorporated liposomes to promote PD-L1 multivalent binding for effective immune checkpoint blockade therapy

Immune checkpoint blockade(ICB)therapy targeting PD-L1 via monoclonal antibody(m Ab)has shown extensive clinical benefits in the diverse types of advanced malignancies.However,most patients are completely refractory to ICB therapy owing to the PD-L1 recycling mechanism.Herein,we propose photo-induced crosslinked and anti-PD-L1 peptide incorporated liposomes(immune checkpoint blockade liposomes;ICB-LPs)to promote PD-L1 multivalent binding for inducing lysosomal degradation of PD-L1 in tumor cells.The ICB-LPs are prepared by formulation of DC_(8,9)PC with photo-polymerized diacetylenic moiety,1,2-dipalmitoylphosphatidylcholine(DPPC)and anti-PD-L1peptide(D-form NYSKPTDRQYHF)-conjugated DSPE-PEG_(2k)(anti-PD-L1-DSPE-PEG_(2k))in a molar ratio of 45:45:10,followed by cross-linking of liposomal bilayer upon UV irradiation.The 10 mol% antiPD-L1-DSPE-PEG_(2k)incorporated ICB-LPs have a nano-sized lipid bilayer structure with an average diameter of 137.7±1.04 nm,showing a high stability in serum condition.Importantly,the ICB-LPs efficiently promote the multivalent binding with PD-L1 on the tumor cell membrane,which are endocytosed with aim to deliver PD-L1 to the lysosomes,wherein the durable PD-L1 degradation is observed for72 h,in contrast to anti PD-L1 m Abs showing the rapid PD-L1 recycling within 9 h.The in vitro coculture experiments with CD8^(+)T cells show that ICB-LPs effectively enhance the T cell-mediated antitumor immune responses against tumor cells by blocking the PD-L1/PD-1 axis.When ICB-LPs are intravenously injected into colon tumor-bearing mice,they efficiently accumulate within the targeted tumor tissues via both passive and active tumor targeting,inducing a potent T cell-mediated antitumor immune response by effective and durable PD-L1 degradation.Collectively,this study demonstrates the superior antitumor efficacy of crosslinked and anti-PD-L1 peptide incorporated liposome formulation that promotes PD-L1 multivalent binding for trafficking of PD-L1 toward the lysosomes instead of the recycling endosomes.

Identifying peptides that specifically bind to MDA-MB-468 breast cancer cells

Objective To use phage display technique to screen for small polypeptides that specifically bind to MDA-MB-468 cells.Methods A random heptapeptide phage display library was used for in vitro screening against target MDA-MB-468 cells.SC1180 cells were used for subtractive selection.High-affinity phage DNA was extracted,and peptides were sequenced.Results(1)The original library capacity of the polypeptide library was 2×10^13 pfu/mL,and phage titer was determined over 4 rounds.The average library capacity was 1.8×10^13 pfu/mL.(2)Subtractive screening showed that the phage library volume of each round was 1.8×10^12 pfu/mL,and that there was an enrichment effect in each subsequent round.Screening was stopped after the fourth round.(3)PCR results showed that the size of 39 products(78.0%)and 11 products(22%),were 300 bp and 258 bp,respectively.Thirty positive phages were selected for DNA extraction and sequencing,and the corresponding amino acid sequence was LMTRXSK.The sequence had no homology with known genes or proteins.Conclusion Using the phage display technique,we identified that the short polypeptide,LMTRXSK,specifically binds MDA-MB-468 human breast cancer cells.

The novel amyloid-beta peptide aptamer inhibits intracellular amyloid-beta peptide toxicity

Amyloid β peptide binding alcohol dehydrogenase （ABAD） decoy peptide （DP） can competitively antagonize binding of amyloid β peptide to ABAD and inhibit the cytotoxic effects of amyloid β peptide. Based on peptide aptamers, the present study inserted ABAD-DP into the disulfide bond of human thioredoxin （TRX） using molecular cloning technique to construct a fusion gene that can express the TRX1-ABAD-DP-TRX2 aptamer. Moreover, adeno-associated virus was used to allow its stable expression. Immunofluorescent staining revealed the co-expression of the transduced fusion gene TRX1-ABAD-DP-TRX2 and amyloid β peptide in NIH-3T3 cells, indicating that the TRXl-ABAD-DP-TRX2 aptamer can bind amyloid β peptide within cells. In addition, cell morphology and MTT results suggested that TRX1-ABAD-DP-TRX2 attenuated amyloid β peptide-induced SH-SY5Y cell injury and improved cell viability. These findings confirmed the possibility of constructing TRX-based peptide aptamer using ABAD-DP. Moreover, TRXl-ABAD-DP-TRX2 inhibited the cytotoxic effect of amyloid β peptide.

The calcium-binding activity of fish scale protein hydrolysates

The calcium-binding activity of tilapia scale protein hydrolysates sequentially hydrolyzed by trypsin, flavor enzyme and pepsin were investigated. The hydrolysates were divided into four fractions using G-15 gel chromatography, and the F3 fraction has the higher calcium-binding activity of 196.3 mg/g. The UV-vis and the Fourier transform infrared spectroscopy (FTIR) demonstrate that the amino nitrogen atoms and the oxygen atoms belonging to the carboxylate groups are the primary binding sites for Ca2+. The X-ray diffraction and scanning electron microscopy (SEM) confirmed the reaction between the peptde and calcium. The results obtained indicated that this fish scale protein hydroly-sates have potential as functional foods for calcium-supplementation.

The Covalent Binding of Genistein to the Non-prosthetic-heme-moiety of Bovine Lactoperoxidase Leads to Enzymatic Inactivation

Objective Genistein, a major soy isoflavone metabolite （SIF）, inactivates oxidation activity of bovine lactoperoxidase （LPO）. Modification of the heme moiety of LPO by nitrogen-containing compounds has been shown to inactivate LPO. In contrast, SIF mediated inactivation of LPO does not involve a heme modification and the mechanism of SIF inhibition is poorly understood. Methods After inactivation of LPO by genistein in the presence of H202, trypsin-digested LPO peptide fragments were collected and analyzed by MALDI-TOF-MS to characterize the chemical binding of genistein（s） to LPO. Results The heme moiety of LPO was not modified by genistein. A covalent binding study showed that 3H-genistein bound to LPO with a ratio of ~12 to 1. After HPLC analysis and peak collection, trypsin-digested peptide fragments were analyzed by MALDI-TOF-MS. The 3H-genistein co-eluted peptide fragments （RT=24 min） were putatively identified as 1991VGYLDEEGVLDQNR214 with two bound genistein molecules or a genistein dimer （2 259 Da）, 486TPDNIDIWlGGNAEPMVER504 with two bound genistein molecules or a genistein dimer （2 663 Da）, and 161ARWLPAEYEDGLALPFGWTQR182 with three bound genistein molecules or a genistein trimer （3 060 Da）. The fragment with a mass of 2 792 Da （RT=36 min） was identified as 132CDENSPYR139 with three genistein molecules or a genistein trimer. Conclusions The results suggest that LPO was inactivated by irreversible covalent binding of genistein or genistein polymers to particular peptide fragments constituting regions of the outward domain. No genistein interaction with the prosthetic heme moiety of LPO was observed.

Fluorescence Resonance Energy Transfer Competitive Binding Assay for Secretin Receptor （Class B-GPCR）

Human secretin is responsible for carrying a number of physiological functions including energy and water homeostasis, thus making secretin receptor a promising target for drug development. For GPCRs （G protein-coupled receptors）, radioactive ligands are usually used in conventional binding assays to characterize the binding affinities of the ligands. An alternative non-hazardous fluorescence based binding assay is lucrative over the radio-ligand assays. Here, we have developed a FRET （fluorescence resonance energy transfer） competitive binding assay for human secretin receptor. The receptor gene sequence is cloned in the SNAP （single nucleotide amplified polymorphisms） tag-plasmid and expressed in CHO （chinese hamster ovary）-K1 cells. Its expression and function is confirmed with immunofluorescence localization and receptor activation. The receptor and the ligand are labeled with fluorescent donor （Tb） and acceptor （Alexa488）. FRET signals are produced when the labeled ligand is bound to the receptor and the same drop when it is displaced by the test compounds. The saturation concentration of the receptor labeling is 100 nM, and the ligand Kd value is 500 nM. At these concentrations, the IC50 of unlabeled secretin is 1.63 4- 3.55 nM. Additionally, few class-B ligands are screened and hold good correlation with traditional radio-ligand assay. Henceforth, this FRET binding assay can be efficiently used as a primary screening tool for peptide analogs.

Effect of covalent-binding modes of osteogenic-related peptides with artificial carriers on their biological activities in vivo

Covalent binding between bioactive substances and materials in different ways can significantly improve the bone inductivity and biological activity of bone repair materials.However,there is a lack of systematic understanding of how these binding modes affect biological activities of the active substances.In this study,four kinds of functionalized Multi-walled carbon nanotubes(MWCNTs)were prepared,ensuring the same grafting rate of different functional groups.Subsequently,two kinds of osteogenic-related peptides,bone morphogenetic protein-2 mimicking peptides and osteogenic growth mimicking peptides,were covalently bound to functionalized MWCNTs,ensuring the same molar mass of peptides bound to different functionalized MWCNTs in this process.Then the same amount of functionalized MWC-NTs/Peptides composites were introduced into the scaffolds,and through the ectopic osteogenesis model in rats and calvarial defect model in rabbits,ectopic osteogenesis and bone repair ability of the composites were analyzed.Furthermore,the effects of different covalent binding modes on peptide-induced osteogenesis and bone repair were studied.The results showed that the negative influencing trend of different covalent binding modes of osteogenic-related peptides with artificial carriers on their biological activities was in the order as follows:amide binding(carboxyl)>silane coupling>dopamine bind-ing>amide binding(amino),whose mechanism might be mainly that the covalent binding of peptides with different functional groups resulted in different charges.We believe that the results of this study have important guiding significance for the research and development of bone repair materials covalently bound with bioactive substances.

Principles of amino-acid–ribonucleotide interaction revealed by binding affinities between homogeneous oligopeptides and singlestranded RNA molecules

We have determined the binding strengths between ribonucleotides of adenine(A),guanine(G),uracil(U),and cytosine(C)in homogeneous single-stranded ribonucleic acids(ssRNAs)and homo-decapeptides consisting of 20 common amino acids.We use a bead-based fluorescence assay for these measurements in which decapeptides are immobilized on the bead surface and ssRNAs are in solutions.The results provide a molecular basis for analyzing selectivity,specificity,and polymorphisms of amino-acid–ribonucleotide interactions.Comparative analyses of the distribution of the binding energies reveal unique binding strength patterns assignable to each pair of amino acid and ribonucleotide originating from the chemical structures.Pronounced favorable(such as Arg–G)and unfavorable(such as Met–U)binding interactions can be identified in selected groups of amino acid and ribonucleotide pairs that could provide basis to elucidate energetics of amino-acid–ribonucleotide interactions.Such interaction selectivity,specificity,and polymorphism manifest the contributions from RNA backbone,RNA bases,as well as main chain and side chain of the amino acids.Such characteristics in peptide–RNA interactions might be helpful for understanding the mechanism of protein–RNA specific recognition and the design of RNA nano-delivery systems based on peptides and their derivatives.

金属抗菌肽SIF_(4)对大肠杆菌拓扑异构酶活性及胞内核酸合成的影响

为系统阐明金属抗菌肽SIF_(4)基于DNA拓扑异构酶靶点的非细胞质膜抑菌机理,以大肠杆菌为模式菌株,研究了金属抗菌肽SIF_(4)与基因组DNA的结合方式、对DNA拓扑异构酶I/II活性以及胞内核酸生物合成的影响机理。研究发现,金属抗菌肽SIF_(4)可能以类似溴化乙锭嵌插方式与基因组DNA结合,对拓扑异构酶I有较强抑制活性,但对拓扑异构酶II影响较小,可通过影响DNA负超螺旋解链和RNA聚合酶结合催化RNA转录过程发挥抑菌活性。研究还发现,经金属抗菌肽SIF_(4)处理12 h后,大肠杆菌胞内总DNA和总RNA生物合成量均受到不同程度的抑制,且呈现良好的量-效关系,1/2最小抑菌浓度(minimal inhibitory concentration,MIC)组与对照组(0 MIC)相比,胞内DNA和RNA生物量差异不显著(P>0.05),MIC和2 MIC组与对照组相比,胞内DNA和RNA生物量差异显著(P<0.05)。实验结果可为金抗肽SIF_(4)在食源性大肠杆菌生物防控中的应用提供理论支持。

H-FABP、NT-proBNP与急性心力衰竭患者容量负荷状态及预后的相关性

目的 研究心型脂肪酸结合蛋白(H-FABP)、氨基端脑钠肽前体(NT-proBNP)对急性心力衰竭患者容量负荷状态及预后的评估。方法 本研究为前瞻性研究,以2021年1月至2022年1月于安阳市人民医院急诊住院的老年急性心力衰竭患者83例作为研究组,另选取83例健康者作为对照组。根据相对容量平衡水平,将以上83例患者分为容量超负荷组和非容量超负荷组,对所有出院患者随访3个月,将发生死亡的患者归为死亡组,其余为生存组。比较研究组与对照组不同容量负荷、不同预后的H-FABP、NT-proBNP水平之间的差异,研究H-FABP、NT-proBNP与生存状况以及容量负荷状态的相关性。结果 研究组患者的H-FABP、NT-proBNP水平高于对照组(P<0.001);容量超负荷组患者的H-FABP、NT-proBNP水平高于非容量超负荷组(P<0.05);死亡组患者的H-FABP、NT-proBNP水平高于生存组(P<0.05)。通过相关性分析,患者的死亡以及容量超负荷与H-FABP、NT-proBNP呈现正相关(P<0.001)。结论 H-FABP、NT-proBNP与急性心力衰竭患者容量负荷状态及预后呈现相关性,有助于评估急性心力衰竭的严重程度,对预后不良患者起到积极的指导治疗作用。

大球盖菇咸味肽的受体感知机制研究

目的探究在不同咸味受体共存体系下,受体的大球盖菇咸味肽识别和结合特性,受体对咸味肽的竞争结合机制。方法采用分子互作技术构建了多受体-肽分子竞争结合体系,研究了咸味受体上皮细胞Na+通道的阿米洛利敏感钠离子通道蛋白(amiloride sensitive sodium channel protein,SCNN)1α、SCNN1β和SCNN1γ3个亚基受体,与咸味受体TRPV1共存体系下,对大球盖菇咸味肽KSWDDFFTR(KR-9P)的竞争结合特性。结果咸味肽KR-9P能够同时被多种咸味受体识别和结合。SCNN1β、SCNN1γ和TRPV1受体共存的多受体-肽分子竞争结合体系中,分子间结合反应遵循焓减放热反应,肽分子数量(饱和/非饱和)和受体结合顺序,对分子间的结合影响不大,受体和肽分子之间发生多位点、多数量的分子结合,分子间结合亲和力处于强结合水平(10^(–9)~10^(–8)M)。多个互作分子共存的混合体系并不利于熵驱动的SCNN1α受体结合肽分子的反应发生,分子间结合亲和力在中等水平(10^(–4)M)。结论不同咸味受体在竞争结合咸味肽时展现出不同的互作机制。SCNN1β、SCNN1γ和TRPV1受体共存会产生咸味肽感知呈味增效的效果,SCNN1α和TRPV1受体之间的肽分子竞争结合,会影响SCNN1α受体感知结合咸味肽。本研究解析了不同咸味受体竞争结合咸味肽的互作机制,为理解咸味肽的受体感知机制提供参考。

HLA分子重构法检测多肽与HLA-B*1301的结合力

目的:建立弱酸处理后细胞表面HLA分子重构法检测多肽与HLA-B*1301的结合力,并评估其实用性。方法:采用不同pH的柠檬酸缓冲液处理高表达HLA-B*1301的C1R细胞不同时间,中和pH后用含β2m蛋白、布雷非德菌素A的培养液重悬细胞,加入多肽(多肽组)或不加多肽(空白对照)37℃孵育,加入抗HLA抗体后采用流式细胞术检测,以多肽组与空白对照组荧光强度的比值作为衡量HLA分子重构水平强弱的指标,进而代表多肽与HLA-B*1301分子的结合力。结果:pH3.0的缓冲液处理1 min的条件下,HLA-多肽复合物变性解离,细胞表面只保留HLA重链分子,添加具有结合力的多肽可显著提升HLA分子重构水平,可以此评价多肽与HLA-B*1301的结合力。结论:HLA分子重构法检测多肽与HLA-B*1301的结合力操作简便,结果可靠,也可为研究其他低频HLA分子抗原递呈模式提供参考。

草鱼MHCⅠα基因克隆及其多态性特征分析

主要组织相容性复合体(MHC)是存在于脊椎动物染色体上、呈高度多态性的基因群,与机体的抗病性密切关系。MHCⅠ类分子由α链和β_(2m)微球蛋白组成,α链呈高度多态性。为探究草鱼MHCⅠα基因的多态性特征,本研究对3个草鱼个体的MHCⅠα基因进行克隆和测序,并使用生物信息学方法分析比较草鱼与小鼠、牛和鸡的MHCⅠα基因多态性特征。结果:共获得了5条草鱼MHCⅠα基因型序列,其基因编码332个氨基酸,包括信号肽、α1、α2、α3和TM/CY区域。草鱼MHCⅠα基因的氨基酸变异位点主要分布在α1和α2区域,与小鼠、牛和鸡MHCⅠα基因肽结合区(PBR)空间结构相似,多态性位点分布在抗原递呈的关键部位α螺旋或β折叠上。草鱼MHCⅠα基因的进化受自然环境的负向选择作用,而其他3个物种的进化方式均为正向选择。此外,草鱼MHCⅠα基因与其他脊椎动物亲缘关系较远,单独构成进化树上一大分支,且个体间继续分化为不同的亚支。本研究从基因层面阐述了草鱼MHCⅠα基因多态性特征和分子进化规律,为进一步探究低等脊椎动物MHCⅠα基因的生物学特征奠定基础。

基于心功能及IGFBP7、sST2、CGRP、ET分析沙库巴曲缬沙坦在治疗冠心病合并慢性心力衰竭中的应用效果

目的 分析冠心病(CHD)合并慢性心力衰竭(CHF)患者应用沙库巴曲缬沙坦治疗的效果。方法 选择2020年1月至2023年1月邯郸市第四医院收治的86例CHD合并CHF患者,以随机数字表法将其分为对照组和试验组各43例。两组CHD治疗均应用硝酸酯类、他汀类及抗血小板药物,对照组CHF治疗应用坎地沙坦酯片、醛固酮受体拮抗剂及β受体阻滞剂,试验组治疗则将对照组中的坎地沙坦酯片替换为沙库巴曲缬沙坦钠片。比较两组疗效、不良反应、心功能指标[左室短轴缩短率(LVFS)、左室射血分数(LVEF)、6min步行距离(6 MWD)]、心室重构指标[Ⅲ型胶原前肽(PⅢP)、层粘蛋白(LN)、基质金属蛋白酶-9(MMP-9)]、心肌损伤和血管内皮功能相关指标[胰岛素样生长因子结合蛋白7(IGFBP7)、可溶性生长刺激表达基因2(sST2)、降钙素基因相关肽(CGRP)、内皮素(ET)]。结果与对照组比,试验组治疗3个月后的总有效率更高,差异有统计学意义(P<0.05)。两组治疗3个月后的LVFS、LVEF、6 MWD、IGFBP7、CGRP与治疗前比升高,且试验组与对照组比更高,差异有统计学意义(P<0.05);PⅢP、LN、MMP-9、sST2、ET降低,试验组与对照组比更低,差异有统计学意义(P<0.05)。两组不良反应总发生率对比差异无统计学意义(P>0.05)。结论 沙库巴曲缬沙坦可有效调节CHD合并CHF患者IGFBP7、sST2、CGRP、ET,改善血管内皮功能、心肌损伤、心室重构及心功能,进而可提高疗效,且具有良好的安全性。

源自蜡样芽孢杆菌抗菌肽DB16的筛选及其对金黄色葡萄球菌的抑菌机制

本实验发现当与蜡样芽孢杆菌混合培养时,金黄色葡萄球菌的生长受到抑制。结合生物信息学方法从蜡样芽孢杆菌DeadBoxATP依赖性RNA解旋酶中预测、筛选得到抗菌肽DB16(RKLLQFAKKLGIVFTK)。抗菌肽DB16对金黄色葡萄球菌的最低抑菌质量浓度(minimum inhibitory concentration,MIC)为31.25μg/mL,可在0.5 h内完全抑制金黄色葡萄球菌的生长;抗菌肽DB16在磷酸盐缓冲溶液中呈现无规卷曲结构,在十二烷基硫酸钠环境中转变为α-螺旋结构。采用荧光探针、流式细胞术、透射电子显微镜、DNA凝胶电泳以及圆二色谱等方法探究抗菌肽DB16对金黄色葡萄球菌的抑菌机制,结果表明,抗菌肽DB16能够改变细菌细胞膜通透性,造成细胞内容物外泄,同时进入胞内与金黄色葡萄球菌基因组DNA结合,影响正常DNA的复制,最终抑制菌体的生长繁殖。此外,对哺乳动物红细胞的处理表明,DB16在8×MIC条件下仍无溶血性。综上,源自蜡样芽孢杆菌的抗菌肽DB16在金黄色葡萄球菌防控方面具有很大应用潜力。

蛋清多肽-铁螯合物的制备、表征及对Caco-2细胞的促增殖作用

为开发人体易吸收的铁补充剂,提高咸蛋清的附加值,该研究以铁螯合能力和水解度(degree of hydrolysis,DH)为指标,优化酶解条件,通过超滤和Sephadex G-15凝胶柱分离纯化铁螯合能力高的蛋清多肽。采用扫描电镜、能谱、红外光谱和X射线衍射(X-ray diffraction,XRD)对蛋清多肽-铁螯合物结构进行表征。同时探究其对Caco-2细胞活力的影响。结果表明,最佳酶解条件为底物质量分数4%、酶添加量10%、pH 8、温度50℃时酶解8 h,所得产物的铁螯合能力为95.27%。蛋清粗肽经超滤和Sephadex G-15分离纯化得到铁螯合能力最高的组分F4-4。扫描电镜、能谱、红外光谱和XRD结果表明蛋清多肽和Fe2+形成多肽-铁螯合物。细胞实验中,与蛋清多肽和硫酸亚铁相比,蛋清多肽-铁螯合物的安全性高,且有一定的促增殖作用。

副干酪乳杆菌发酵液中抗菌肽的筛选及对副溶血性弧菌的抑菌作用

副溶血性弧菌是一种常见的食源性致病菌,严重威胁食品安全和人体健康。本研究利用超高效液相色谱-质谱联用技术鉴定副干酪乳杆菌发酵液中的多肽序列,并通过生物信息学筛选出可能的抗菌序列(RQQAENLAKFAKKG),命名为Yt9z。研究结果表明其对副溶血性弧菌的最低杀菌质量浓度(MBC)为125μg/mL,可在3 h内将细菌完全杀死。通过膜通透、透射电镜、DNA凝胶阻滞分析、圆二色谱等试验探究其抑菌机制,结果在不同溶液环境下,抗菌肽Yt9z能改变自身的二级结构,进而增加细菌细胞膜通透性,并穿透细胞膜与DNA结合使其死亡。这些发现为抗菌肽Yt9z应用于副溶血性弧菌污染提供了理论参考。