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61.
Initial Molecular Recognition Steps of McjA Precursor during Microcin J25 Lasso Peptide Maturation
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Dr. Nadine Assrir Dr. Anna Pavelkova Régine Dazzoni Dr. Rémi Ducasse Dr. Nelly Morellet Dr. Eric Guittet Prof. Sylvie Rebuffat Dr. Séverine Zirah Dr. Yanyan Li Dr. Ewen Lescop 《Chembiochem : a European journal of chemical biology》2016,17(19):1851-1858
Microcin J25 (MccJ25) has emerged as an excellent model to understand the maturation of ribosomal precursor peptides into the entangled lasso fold. MccJ25 biosynthesis relies on the post‐translational modification of the precursor McjA by the ATP‐dependent protease McjB and the lactam synthetase McjC. Here, using NMR spectroscopy, we showed that McjA is an intrinsically disordered protein without detectable conformational preference, which emphasizes the active role of the maturation machinery on the three‐dimensional folding of MccJ25. We further showed that the N‐terminal region of the leader peptide is involved in interaction with both maturation enzymes and identified a predominant interaction of V43–S55 in the core McjA sequence with McjC. Moreover, we demonstrated that residues K23–Q34 in the N‐terminal McjA leader peptide tend to adopt a helical conformation in the presence of membrane mimics, implying a role in directing McjA to the membrane in the vicinity of the lasso synthetase/export machinery. These data provide valuable insights into the initial molecular recognition steps in the MccJ25 maturation process. 相似文献
62.
Cover Picture: Reprogramming the Biosynthesis of Cyclodepsipeptide Synthetases to Obtain New Enniatins and Beauvericins (ChemBioChem 4/2016)
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63.
为了分离制备猪肺抗氧化肽,该文研究了中心组合设计和响应面分析优化猪肺抗氧化肽的提取工艺,以DPPH自由基清除率为响应值,分析了料液比、水解时间和酶浓度对制备抗氧化肽的影响,再通过葡聚糖凝胶Sephadex G-50、G-25和G-10对抗氧化肽进行分离纯化,得到了具有抗氧化活性的肽段,测定其清除DPPH自由基、超氧阴离子、ABTS自由基、羟基自由基以及金属螯合的能力。猪肺抗氧化肽的最佳提取工艺参数为:新鲜猪肺质量与水质量的比例(料液比)为1∶3,水解6 h,酶浓度为6 500 U/g,此时DPPH自由基清除率为66.89%;抗氧化活性最强的组分A5清除DPPH自由基、超氧阴离子、ABTS自由基和羟基自由基的IC50分别为0.073、0.989、0.192和1.261 g/L,金属螯合能力的IC50为6.505 g/L;其相对分子质量为175。 相似文献
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66.
以海参肽得率为指标,分别考察了酶解加酶量、时间、pH、温度、底物浓度对胰蛋白酶酶解海参蛋白质反应的影响。通过正交实验确定了胰蛋白酶酶解海参蛋白的最佳工艺条件:酶加量6 000 U/g,水解反应时间3 h,温度55℃,pH 8.0,底物浓度1.0%,在此条件下,海参肽得率可达32.93%。 相似文献
67.
以英红九号红茶渣经碱溶酸沉提取的茶蛋白为研究对象,血管紧张素转化酶(ACE)抑制率为评价指标,通过单因素试验和响应面优化得到茶蛋白ACE抑制肽的最佳制备工艺,并对酶解物进行氨基酸组成分析、超滤膜分离和不同分子量组分的ACE抑制活性分析。结果表明,英红九号茶蛋白ACE抑制肽的最优酶解工艺为酶解温度37℃、3.20 h、p H值7.20、底物质量分数3%、酶底质量比0.40%,在此条件下进行的验证试验ACE抑制率为83.38%,与理论值84.48%较相符。英红九号茶蛋白ACE抑制肽酶解物富含必需氨基酸(33.03%)和对ACE抑制活性有重要意义的疏水性氨基酸(47.20%),且经超滤膜分离所得<3ku组分的ACE抑制活性(IC50=0.85 mg/mL)要显著强于酶解物(IC50=1.37 mg/mL)和>3 ku组分(IC50=2.81 mg/mL)。该研究为食源性ACE抑制肽的研究开发和英红九号茶蛋白的高值化利用提供了理论依据。 相似文献
68.
Mariarosaria Conte Rosanna Palumbo Alessandra Monti Elisabetta Fontana Angela Nebbioso Menotti Ruvo Lucia Altucci Nunzianna Doti 《International journal of molecular sciences》2022,23(1)
The AIF/CypA complex exerts a lethal activity in several rodent models of acute brain injury. Upon formation, it translocates into the nucleus of cells receiving apoptotic stimuli, inducing chromatin condensation, DNA fragmentation, and cell death by a caspase-independent mechanism. Inhibition of this complex in a model of glutamate-induced cell death in HT-22 neuronal cells by an AIF peptide (AIF(370-394)) mimicking the binding site on CypA, restores cell survival and prevents brain injury in neonatal mice undergoing hypoxia-ischemia without apparent toxicity. Here, we explore the effects of the peptide on SH-SY5Y neuroblastoma cells stimulated with staurosporine (STS), a cellular model widely used to study Parkinson’s disease (PD). This will pave the way to understanding the role of the complex and the potential therapeutic efficacy of inhibitors in PD. We find that AIF(370-394) confers resistance to STS-induced apoptosis in SH-SY5Y cells similar to that observed with CypA silencing and that the peptide works on the AIF/CypA translocation pathway and not on caspases activation. These findings suggest that the AIF/CypA complex is a promising target for developing novel therapeutic strategies against PD. 相似文献
69.
Jinquan Fan Binbin Li Qianming Hong Zeyu Yan Xinjun Yang Kecheng Lu Guoliang Chen Lei Wang Yihong Chen 《International journal of molecular sciences》2022,23(1)
In shrimp, several glutathione peroxidase (GPX) genes have been cloned and functionally studied. Increasing evidence suggests the genes’ involvement in white spot syndrome virus (WSSV)- or Vibrio alginolyticus-infection resistance. In the present study, a novel GXP gene (LvGPX3) was cloned in Litopenaeus vannamei. Promoter of LvGPX3 was activated by NF-E2-related factor 2. Further study showed that LvGPX3 expression was evidently accelerated by oxidative stress or WSSV or V. alginolyticus infection. Consistently, downregulated expression of LvGPX3 increased the cumulative mortality of WSSV- or V. alginolyticus-infected shrimp. Similar results occurred in shrimp suffering from oxidative stress. Moreover, LvGPX3 was important for enhancing Antimicrobial peptide (AMP) gene expression in S2 cells with lipopolysaccharide treatment. Further, knockdown of LvGPX3 expression significantly suppressed expression of AMPs, such as Penaeidins 2a, Penaeidins 3a and anti-lipopolysaccharide factor 1 in shrimp. AMPs have been proven to be engaged in shrimp WSSV- or V. alginolyticus-infection resistance; it was inferred that LvGPX3 might enhance shrimp immune response under immune challenges, such as increasing expression of AMPs. The regulation mechanism remains to be further studied. 相似文献
70.
目的 优化海蜇低分子肽(low molecular weight peptide from Rhopilema esculentum Kishinouye, RKLP)制备工艺,评价其抗氧化活性及分析氨基酸组成。方法 海蜇利用碱性和中性蛋白酶双酶分步酶解制备海蜇肽,以1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除率为指标,响应面实验优化酶解工艺条件。采用超滤技术,获得分子量≤3.5 kDa RKLP。通过测定DPPH自由基、2,2’-联氮-双-3-乙基苯并噻唑啉-6-磺酸[2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonicacid),ABTS]自由基及超氧阴离子(O2-)自由基的清除率,评价RKLP抗氧化活性。氨基酸分析仪分析RKLP氨基酸组成。结果 酶解制备海蜇抗氧化肽的最佳工艺条件为:酶解温度50℃、3%碱性蛋白酶pH 7.5酶解2 h、1%中性蛋白酶pH 7.0酶解2 h,所得的DPPH自由基清除率为71.52%±0.59%,接近与预测值70.57%。RKLP水解度为6... 相似文献