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1.
J Inorg Biochem ; 202: 110858, 2019 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-31689625

RESUMO

We report the migration of platinum ligand unit {Pt(en)}2 (en = ethylenediamine) on a short peptide during collision-induced dissociation fragmentation combined with the characterization of the same species by 2D [1H,15N] HSQC (Heteronuclear Single Quantum Coherence) NMR spectroscopy. The NMR spectrum showed that the cysteine is platinated while the MS/MS (Tandem mass spectrometry) showed the platination at glutamic acid. Our results provide the first experimental evidence of platinum migration on peptide during collision-induced dissociation.

2.
Anal Bioanal Chem ; 411(15): 3257-3268, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31089788

RESUMO

It has been demonstrated that triterpenes in Alismatis rhizoma (Zexie in Chinese, ZX) contributed to the lipid-lowering effect on high-fat diet-induced hyperlipidemia. Alisol B 23-acetate, one of the abundant triterpenes in ZX, was used as the marker of quality control for ZX in Chinese Pharmacopoeia, while it could not reflect the lipid-lowering effect because other triterpenes in ZX also had prominent medicinal efficacy. To identify the significantly bioactive triterpenes in ZX, a multiple reaction monitoring (MRM)-based characteristic chemical profile (CCP)-support vector machine (SVM) model was used to explore the relationship between triterpenes and lipid-lowering effect of ZX. Firstly, the content of 87 targeted triterpenes was quantified by the MRM-based CCP using UHPLC-QTRAP-MS/MS. Secondly, the lipid-lowering effect of 30 ZX samples was assessed by 3T3-L1 preadipocytes. Thirdly, 9 of the 87 triterpenes possessing high mean impact value were identified to have significant lipid-lowering effect via the particle swarm-optimized SVM model. The new SVM model constructed by the 9 triterpenes showed good prediction performance and the overall prediction accuracy reached 81.94%. Finally, the real activity of these triterpenes was partly confirmed and was consistent with the prediction of SVM. These results showed that the method for discovery of triterpenes with prominent lipid-lowering activity in ZX was reliable. The proposed method is expected to provide an efficient and rapid approach for screening of active component and drug discovery in traditional herbs. Graphical abstract.


Assuntos
Alismataceae/química , Hipolipemiantes/química , Hipolipemiantes/farmacologia , Rizoma/química , Máquina de Vetores de Suporte , Triterpenos/química , Triterpenos/farmacologia , Células 3T3-L1 , Adipogenia/efeitos dos fármacos , Animais , Cromatografia Líquida de Alta Pressão , Descoberta de Drogas/métodos , Avaliação Pré-Clínica de Medicamentos/métodos , Hiperlipidemias/tratamento farmacológico , Metabolismo dos Lipídeos/efeitos dos fármacos , Lipídeos/análise , Camundongos , Espectrometria de Massas em Tandem
3.
Phytomedicine ; 59: 152803, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31005811

RESUMO

BACKGROUND: Chrysanthemi Flos (CF), as a popular traditional Chinese medicine (TCM), has five main cultivars in China, namely "Chuju", "Boju", "Gongju", "Huaiju" and "Hangju". Due to their habitats and processing methods, great quality variations occur yet no systematical study has ever been carried out to evaluate such variations. PURPOSE: In this study, we aim to establish a new approach that can serve both as a quality control method and as an identification method for cultivars of CF. METHOD: The components in CF samples were identified by a combination of UPLC-ESI-Q-TOF/MS and GC/MS. Furthermore, a multimodal quantitative method was established by UPLC-UV coupled with principal component analysis (PCA) and the similarity evaluation system (SES), which was used to control and identify four cultivars of CF. RESULTS: 18 compounds of flavonoids and caffeoylquinic acids were identified and ten of them were quantified using UPLC-ESI-Q-TOF/MS. Different cultivars of CF could be clearly distinguished with the fingerprints evaluation and principal component analysis (PCA). A total of 74 volatile compounds were detected by GC/MS. The distinctness of volatile components was observed. By the combination of UPLC-ESI-Q-TOF/MS and GC/MS, an identification and quality control method for CF was successfully established. CONCLUSION: The combination of UPLC-ESI-Q-TOF/MS and GC/MS could act as a comprehensive multimodal method for both identification and quality control of herbal medicines. This study provided new insights into the overall evaluation method for herbal medicines possessing different cultivars.


Assuntos
Chrysanthemum/química , Medicamentos de Ervas Chinesas/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Espectrometria de Massas por Ionização por Electrospray/métodos , China , Cromatografia Líquida de Alta Pressão/métodos , Medicamentos de Ervas Chinesas/química , Flavonoides/análise , Flores/química , Cromatografia Gasosa-Espectrometria de Massas/estatística & dados numéricos , Análise de Componente Principal , Controle de Qualidade , Ácido Quínico/análogos & derivados , Ácido Quínico/análise , Espectrometria de Massas por Ionização por Electrospray/estatística & dados numéricos , Compostos Orgânicos Voláteis/análise
4.
J Pharm Biomed Anal ; 171: 148-157, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-30999225

RESUMO

Lysophospholipids (Lyso-PLs) are lipid-derived signaling molecules which were demonstrated to have a strong correlation with the progression of atherosclerosis. In this study, we investigated the influence of high-fat diet on Lyso-PL profiles of atherosclerosis-prone apolipoprotein E-deficient (ApoE-/-) mice and wild type C57BL/6 J mice to find out the potential biomarkers associated with atherosclerosis. Firstly, the quantitative profiling method for Lyso-PLs based on ultra-performance liquid chromatography-quadrupole linear ion trap mass spectrometry (UPLC-QTRAP-MS/MS) was established and validated. Secondly, this method was utilized to quantify 169 targeted Lyso-PLs in plasma samples of ApoE-/- mice and wild type C57BL/6 J mice collected at different time points. Finally, 12 of 37 differential Lyso-PLs were identified as more reliable biomarkers by integrating static metabolomics and time-dependent analyses, among which Lyso-PC/15:0, 18:1/Lyso-PI, 22:5/Lyso-PI and 22:4/Lyso-PI were highly correlated with TCand LDL-C levels. Meanwhile, we found that the Lyso-PL profiles of ApoE-/- mice and C57BL/6 J mice were distinguished by altered metabolism of different Lyso-PLs classes, while C57BL/6 J mice fed with high-fat diet and normal diet were discriminated by the content differences of Lyso-PLs with same fatty acid composition. In conclusion, these results provided detailed changes of Lyso-PL profiles associated with atherosclerosis and the differential Lyso-PLs with reasonable change trends may serve as promising biomarkers for atherosclerosis progression.

5.
Anal Chem ; 91(9): 6035-6042, 2019 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-30990031

RESUMO

A new proteomic strategy combining functionalized magnetic nanoparticle affinity probes with mass spectrometry was developed to capture and identify proteins specifically responding to 1,2-d(GpG) intrastrand cisplatin-cross-linked DNA, the major DNA lesion caused by cisplatin and thought to induce apoptosis. A 16-mer oligodeoxynucleotide (ODN) duplex and its cisplatin-cross-linked adduct were immobilized on magnetic nanoparticles via click reaction, respectively, to fabricate negative and positive affinity probes which were very stable in cellular protein extracts due to the excellent bio-orthogonality of click chemistry and the inertness of covalent triazole linker. Quantitative mass spectrometry results unambiguously revealed the predominant binding of HMGB1 and HMGB2, the well-established specific binders of 1,2-cisplatin-cross-linked DNA, to the cisplatin-cross-linked ODN, thus validating the accuracy and reliability of our strategy. Furthermore, 5 RNA or single-stranded DNA binding proteins, namely, hnRNP A/B, RRP44, RL30, RL13, and NCL, were demonstrated to recognize specifically the cisplatinated ODN, indicating the significantly unwound ODN duplex by cisplatin cross-linking. In contrast, the binding of a transcription factor TFIIFa to DNA was retarded due to cisplatin damage, implying that the cisplatin lesion stalls DNA transcription. These findings promote understanding in the cellular responses to cisplatin-damaged DNA and inspire further precise elucidation of the action mechanism of cisplatin.

6.
Molecules ; 24(3)2019 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-30736320

RESUMO

The discovery of the anticancer activity of cisplatin and its clinical application has opened a new field for studying metal-coordinated anticancer drugs. Metal-based anticancer drugs, such as cisplatin, can be transported to cells after entering into the human body and form metal⁻DNA or metal⁻protein adducts. Then, responding proteins will recognize adducts and form stable complexes. The proteins that were binding with metal-based anticancer drugs were relevant to their mechanism of action. Herein, investigation of the recognition between metal-based anticancer drugs and its binding partners will further our understanding about the pharmacology of cytotoxic anticancer drugs and help optimize the structure of anticancer drugs. The "soft" ionization mass spectrometric methods have many advantages such as high sensitivity and low sample consumption, which are suitable for the analyses of complex biological samples. Thus, MS has become a powerful tool for the identification of proteins binding or responding to metal-based anticancer drugs. In this review, we focused on the mass spectrometry-based quantitative strategy for the identification of proteins specifically responding or binding to metal-based anticancer drugs, ultimately elucidating their mechanism of action.


Assuntos
Antineoplásicos/química , Antineoplásicos/farmacologia , Espectrometria de Massas , Metais/química , Proteômica , Animais , Humanos , Estrutura Molecular , Proteômica/métodos , Fluxo de Trabalho
7.
Phytochem Anal ; 30(3): 268-277, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30548356

RESUMO

INTRODUCTION: Lycorine, one of the most common alkaloids in Lycoris spp., is believed to possess pharmacological activity. OBJECTIVE: To discover and identify lycorine-type alkaloids in the crude extracts of bulbs from six Lycoris spp. by ultra-high-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) detection. METHODOLOGY: A qualitative analytical method with a data mining strategy was utilised. Based on the fragmentation patterns of standards investigated in positive tandem mass spectrometry (MS/MS) mode, the fragmentation rules of lycorine-type alkaloids were summarised. These types of alkaloids were additionally classified as different subtypes based on structural features and MS/MS fragmentation patterns, and the diagnostic ions for characterisation of different subtypes of alkaloids were designated. RESULTS: Thirty-seven lycorine type alkaloids, including 16 previously undescribed compounds, were efficiently screened out and tentatively identified from the crude extracts of six Lycoris spp. Lycoris sprengri may be a preferable species for studying or extracting lycorine-type alkaloids because of elevated relative concentrations and highest diversity of alkaloids. CONCLUSION: The UHPLC-QTOF-MS and MS/MS data-mining strategy proved useful for the detection and tentative identification of lycorine-type alkaloids in bulbs of Lycoris spp. and could be extended to other Amaryllidaceae genera. The consequent profiling of the lycorine-type alkaloids will be useful in the quality control of raw materials of Lycoris species and the exploration of superior species.


Assuntos
Alcaloides de Amaryllidaceae/química , Cromatografia Líquida de Alta Pressão/métodos , Lycoris/química , Fenantridinas/química , Espectrometria de Massas em Tandem/métodos , Mineração de Dados , Lycoris/classificação , Estrutura Molecular , Extratos Vegetais/química , Raízes de Plantas/química , Especificidade da Espécie , Estereoisomerismo
8.
Pharmaceutics ; 10(4)2018 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-30297638

RESUMO

Capilliposide B (LC-B) and Capilliposide C (LC-C), two new triterpenoid saponins extracted from Lysimachia capillipes Hemsl, exhibit potential anticancer activity both in vitro and in vivo. However, their metabolic process remains unclear. In this study, the metabolic stability of LC-B, LC-C, and Capilliposide A (LC-A, a bioactive metabolite of LC-B and LC-C) was investigated in human, rat, and mouse liver microsomes, respectively. Thereafter, their metabolites were identified and characterized after oral administration in mice. As a result, species difference was found in the metabolic stability of LC-B and LC-C. All three compounds of interest were stable in human and rat liver microsomes, but LC-B and LC-C significantly degraded in mouse liver microsomes. The metabolic instability of LC-B and LC-C was mainly caused by esterolysis. Moreover, 19 metabolites were identified and characterized in mouse biological matrices. LC-B and LC-C mainly underwent deglycosylation and esterolysis, accompanied by dehydration, dehydrogenation, and hydroxylation as minor metabolic reactions. Finally, the metabolic pathway of LC-B and LC-C in mice was proposed. Our results updated the preclinical metabolism and disposition process of LC-B and LC-C, which provided additional information for better understanding efficacy and safety.

9.
Artigo em Inglês | MEDLINE | ID: mdl-29883888

RESUMO

It is challenging to conduct in vivo metabolic study for traditional Chinese medicines (TCMs) because of complex components, unpredictable metabolic pathways and low metabolite concentrations. Herein, we proposed a sensitive strategy to characterize TCM metabolites in vivo at an orally clinical dose using ultra-high performance liquid chromatography-triple quadrupole-linear ion trap mass spectrometry (UHPLC-QTRAP-MS). Firstly, the metabolism of individual compounds in rat liver microsomes was studied to obtain the metabolic pathways and fragmentation patterns. The untargeted metabolites in vitro were detected by multiple ion monitoring-enhanced product ion (EPI) and neutral loss-EPI scans. Subsequently, a sensitive multiple reaction monitoring-EPI method was developed according to the in vitro results and predicted metabolites to profile the in vivo metabolites. Licorice as a model herb was used to evaluate and validate our strategy. A clinical dose of licorice water extract was orally administered to rats, then a total of 45 metabolites in urine, 21 metabolites in feces and 35 metabolites in plasma were detected. Among them, 18 minor metabolites have not been reported previously and 6 minor metabolites were first detected in vivo. Several isomeric metabolites were well separated and differentiated in our strategy. These results suggested that this new strategy could be widely used for the detection and characterization of in vivo metabolites of TCMs.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Glycyrrhiza/química , Extratos Vegetais/química , Extratos Vegetais/metabolismo , Espectrometria de Massas em Tandem/métodos , Animais , Fezes/química , Masculino , Microssomos Hepáticos/metabolismo , Extratos Vegetais/análise , Ratos , Ratos Sprague-Dawley
10.
Angew Chem Int Ed Engl ; 57(30): 9305-9309, 2018 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-29870126

RESUMO

Reaction of the Au-C N chelate [Au(bnpy)Cl2 ] with the full-length zinc finger (ZnF; ZnCys3 His) of HIV nucleocapsid protein NCp7 results in C-S aryl transfer from the AuIII organometallic species to a cysteine of the ZnF. The reaction is general and occurs even for finger 3 of the transcription factor Sp1, containing a ZnCys2 His2 coordination sphere. This reaction is the first demonstration of group transfer from a coordination compound to biologically important zinc fingers, and is especially noteworthy for the ZnCys2 His2 transcription factors. The work expands the corpus of organometallic species which can efficiently modify biomolecules through C-atom transfer. The electronic features of the gold compound leading to this unexpected reaction were explored by X-ray absorption spectroscopy.

11.
Inorg Chem ; 57(1): 218-230, 2018 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-29227104

RESUMO

A combination of two elements' (Au, Zn) X-ray absorption spectroscopy (XAS) and time-dependent density functional theory (TD-DFT) allowed the elucidation of differential substitution pathways of Au(I) and Au(III) compounds reacting with biologically relevant zinc fingers (ZnFs). Gold L3-edge XAS probed the interaction of gold and the C-terminal Cys2HisCys finger of the HIV-1 nucleocapsid protein NCp7, and the Cys2His2 human transcription factor Sp1. The use of model compounds helped assign oxidation states and the identity of the gold-bound ligands. The computational studies accurately reproduced the experimental XAS spectra and allowed the proposition of structural models for the interaction products at early time points. The direct electrophilic attack on the ZnF by the highly thiophilic Au(I) resulted in a linear P-Au-Cys coordination sphere after zinc ejection whereas for the Sp1, loss of PEt3 results in linear Cys-Au-Cys or Cys-Au-His arrangements. Reactions with Au(III) compounds, on the other hand, showed multiple binding modes. Prompt reaction between [AuCl(dien)]2+ and [Au(dien)(DMAP)]3+ with Sp1 showed a partially reduced Au center and a final linear His-Au-His coordination. Differently, in the presence of NCp7, [AuCl(dien)]2+ readily reduces to Au(I) and changes from square-planar to linear geometry with Cys-Au-His coordination, while [Au(dien)(DMAP)]3+ initially maintains its Au(III) oxidation state and square-planar geometry and the same first coordination sphere. The latter is the first observation of a "noncovalent" interaction of a Au(III) complex with a zinc finger and confirms early hypotheses that stabilization of Au(III) occurs with N-donor ligands. Modification of the zinc coordination sphere, suggesting full or partial zinc ejection, is observed in all cases, and for [Au(dien)(DMAP)]3+ this represents a novel mechanism for nucleocapsid inactivation. The combination of XAS and TD-DFT presents the first direct experimental observation that not only compound reactivity, but also ZnF core specificity, can be modulated on the basis of the coordination sphere of Au(III) compounds.

13.
J Chromatogr A ; 1524: 121-134, 2017 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-28985905

RESUMO

It was reported that triterpenes compounds in Alismatis rhizoma (AR) contributed to the lipid lowering effect on high fat diet (HFD)-induced hyperlipidemia. To date only 24 triterpenes (including the isomers) were characterized by LC-QTOF-MS/MS due to the lack of strategies for systematic discovery, classification and identification of triterpenes in AR. In this study, an integrated strategy combining various QTOF-MS/MS and QTRAP-MS/MS scan functions was developed for systematic identification and specific characterization of triterpenes in AR and processed AR. First, MS/MS fragmentation behaviors of different types of triterpenes were investigated and their diagnostic product ions were systematically summarized for discovery and classification of triterpenes. Second, diagnostic product ions were used to filter the data acquired by UHPLC-QTOF MS/MS for efficient identification of targeted triterpenes. Third, MRM-based characteristic chemical profile (CCP) of triterpenes was established using 30 MRM transitions by UHPLC-QTRAP-MS/MS. Fourth, MRM-based CCP was applied for comparative analyses of triterpenes in AR from different regions and from two other processed AR (salt processed AR and bran processed AR). Consequently, a total of 80 triterpenes including 14 novel compounds were identified in the AR, and 7 more triterpenes compounds were discovered using MRM-based CCP in the processed AR. This work is the most comprehensive characterization of triterpenes compounds in AR to date. The established MRM-based CCP of triterpenes compounds can be instructive for qualitative analyses and relative quantitative analyses of triterpenes in AR and its related medicinal products for potential applications including quality control and classification of different AR materials.


Assuntos
Ascomicetos/química , Espectrometria de Massas em Tandem , Triterpenos/química , Espectrometria de Massas em Tandem/instrumentação
14.
Inorg Chem ; 56(20): 12308-12318, 2017 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-28937773

RESUMO

In this work, we examined a series of thiophilic Au(I) compounds based on [Au(L)(PR3)] (L = Cl-, 4-dimethylaminopyridine (dmap); R= ethyl (Et), cyclohexyl (Cy)) for chemoselective auration of the C-terminal HIV nucleocapsid protein NCp7 F2 and the "full" HIV NCp7 (NC, zinc finger (ZnF)) as probes of nucleocapsid topography. The choice of phosphine allowed electronic and steric effects to be considered. The use of the heterocycle "leaving group" allowed us to study the effect of possible π-stacking with the essential tryptophan residue of NC on the reactivity and selectivity, mimicking the naturally occurring interaction between the zinc finger and nucleic acids. We also examined for comparison the "standard" gold-phosphine compound auranofin, which contains an S-bound glucose coordinated to the {Au(PEt3)} moiety. Both the nature of the phosphine and the nature of L affect the reactivity with the C-terminal NCp7 F2 and the "full" NC. 31P NMR spectroscopy showed the formation of long-lived {Au(PR3)}-ZnF species in all cases, but in the case of NCp7 F2, a selective interaction in the presence of the dmap ligand was observed. In the case of auranofin, an unusual Au-His (rather than Au-Cys) coordination was indicated on NC. The overall results suggest that it is useful to consider three aspects of zinc finger structure in considering the profile of chemical reactivity: (i) the zinc-bound cysteines as primary nucleophiles; (ii) the zinc-bound histidine as a "spectator" ligand; and (iii) ancillary groups not bound to Zn but essential for ZnF function such as the essential tryptophan in NCp7 F2 and NC. Modification of fully functional NC zinc finger by the Cy3P-containing species confirmed the inhibition of the NC-SL2 DNA interaction, as evaluated by fluorescence polarization.

15.
J Chromatogr A ; 1521: 110-122, 2017 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-28951052

RESUMO

A three-step strategy was developed for systematic characterization of curcuminoids in turmeric. Based on UHPLC-QTOF-MS/MS analysis, 89 curcuminoids including 16 novel ones were identified in the turmeric samples using this approach. During the identification process, false positive results were excluded by combining the positive and negative ESI-MS/MS analyses. Moreover, the characterization of the keto and enol forms of type A, B and C curcuminoids was first discussed and they were clearly distinguished using negative ESI-MS/MS method with UV spectra analyses. The structures of detected curcuminoids were identified and rationalized in both ion modes. Additionally, the fragmentation behaviors of the 15 types of curcuminoids were clearly illustrated in this work, which will be helpful for detection and identification of corresponding trace curcuminoids in complex turmeric samples using UHPLC-QTOF-MS/MS methods.


Assuntos
Técnicas de Química Analítica/métodos , Cromatografia Líquida de Alta Pressão , Curcuma/química , Espectrometria de Massas em Tandem
16.
Dalton Trans ; 46(19): 6187-6195, 2017 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-28426082

RESUMO

A high mobility group box 1 (HMGB1) protein has been reported to recognize both 1,2-intrastrand crosslinked DNA by cisplatin (1,2-cis-Pt-DNA) and monofunctional platinated DNA using trans-[PtCl2(NH3)(thiazole)] (1-trans-PtTz-DNA). However, the molecular basis of recognition between the trans-PtTz-DNA and HMGB1 remains unclear. In the present work, we described a hydrogen/deuterium exchange mass spectrometry (HDX-MS) method in combination with docking simulation to decipher the interactions of platinated DNA with domain A of HMGB1. The global deuterium uptake results indicated that 1-trans-PtTz-DNA bound to HMGB1a slightly tighter than the 1,2-cis-Pt-DNA. The local deuterium uptake at the peptide level revealed that the helices I and II, and loop 1 of HMGB1a were involved in the interactions with both platinated DNA adducts. However, docking simulation disclosed different H-bonding networks and distinct DNA-backbone orientations in the two Pt-DNA-HMGB1a complexes. Moreover, the Phe37 residue of HMGB1a was shown to play a key role in the recognition between HMGB1a and the platinated DNAs. In the cis-Pt-DNA-HMGB1a complex, the phenyl ring of Phe37 intercalates into a hydrophobic notch created by the two platinated guanines, while in the trans-PtTz-DNA-HMGB1a complex the phenyl ring appears to intercalate into a hydrophobic crevice formed by the platinated guanine and the opposite adenine in the complementary strand, forming a penta-layer π-π stacking associated with the adjacent thymine and the thiazole ligand. This work demonstrates that HDX-MS associated with docking simulation is a powerful tool to elucidate the interactions between platinated DNAs and proteins.

17.
Angew Chem Int Ed Engl ; 56(16): 4464-4467, 2017 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-28319298

RESUMO

Traveling wave ion mobility (TWIM) mass spectrometry (MS) is a powerful method for the structural and conformational analysis of proteins and peptides, enabling the differentiation of isomeric peptides (or proteins) that have the same sequence but are modified at different residues. In this study, the TWIM-MS technique was used to separate isomeric AuI metallopeptide ions that were formed by ZnII displacement from the parent zinc fingers (ZFs). The synthetic gold finger peptides were derived from the C-terminus of the HIV nucleocapsid p7 protein (NCp7-F2) and finger 3 of the Sp1 transcription factor (Sp1-F3). TWIM-MS enabled the acquisition of distinct product ion spectra for each isomer, clearly indicating the binding sites for the major conformers in the presence of multiple coordination possibilities. Collision cross-section measurements showed that the aurated peptide has a slightly more compact structure than the parent zinc compound NCp7-F2, which showed only one conformation.

18.
Inorg Chem ; 55(21): 11396-11407, 2016 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-27934299

RESUMO

The human immunodeficiency virus (HIV) nucleocapsid protein (NCp7) plays significant roles in the virus life cycle and has been targeted by compounds that could lead to its denaturation or block its interaction with viral RNA. Herein, we describe the interactions of platinum(II) and gold(III) complexes with NCp7 and how the reactivity/affinity of potential inhibitors can be modulated by judicious choice of ligands. The interactions of [MCl(N3)]n+ (M = Pt2+ (n = 1) and Au3+ (n = 2); N3 = tridentate chelate ligands: bis(2-pyridylmethyl)methylamine (Mebpma, L1) and bis(2-pyridylmethyl)amine (bpma, L2) with the C-terminal zinc finger of NCp7 (ZF2) were investigated by electrospray ionization-mass spectroscopy (ESI-MS). Mass spectra from the incubation of [MCl(Mebpma)]n+ complexes (PtL1 and AuL1) with ZF2 indicated that they were more reactive than the previously studied diethylenetriamine-containing analogues [MCl(dien)]n+. The initial product of reaction of PtL1 with ZF2 results in loss of all ligands and release of zinc to give the platinated apopeptide {PtF} (F = apopeptide). This is in contrast to the incubation with [PtCl(dien)]+, in which {Pt(dien)}-peptide adducts are observed. Incubation of the Au3+ complex AuL1 with ZF2 gave AuxFn+ species (x = 1, 2, 4, F = apopeptide) again with loss of all ligands. Furthermore, the formally substitution-inert analogues [Pt(N3)L]2+ (L = 4-methylpyridine (4-pic), 4-dimethylaminopyridine (dmap), and 9-ethylguanine (9-EtGua)) were prepared to examine stacking interactions with N-acetyltryptophan (N-AcTrp), the Trp-containing ZF2, and the "full" two-finger NCp7 itself using fluorescence quenching titration. Use of bpma and Mebpma gave slightly higher affinity than analogous [Pt(dien)L)]2+ complexes. The dmap-containing complexes (PtL1a and PtL2a) had the greatest association constants (Ka) for N-AcTrp and ZF2 peptide. The complex PtL1a had the highest Ka when compared with other known Pt2+ analogues: [Pt(dien)(9-EtGua)]2+ < [Pt(bpma)(9-EtGua)]2+ < [Pt(dien)(dmap)]2+< PtL2a < PtL1a. A Ka value of ca. 40.6 ± 1.0 × 103 M-1 was obtained for the full NCp7 peptide with PtL1a. In addition, the mass spectrum of the interaction between ZF2 and PtL1a confirms formation of a 1:1 PtL1a/ZF2 adduct. The reactivity of selected complexes with sulfur-containing amino acid N-acetylcysteine (N-AcCys) was also investigated by 195Pt and 1H NMR spectroscopy and ESI-MS. The precursor compounds [PtCl(N3)]+ PtL1 and PtL2 reacted readily, whereas their [Pt(N3)L]2+ analogues PtL1a and PtL2a were inert to substitution.


Assuntos
Fármacos Anti-HIV/química , Fármacos Anti-HIV/farmacologia , Ouro/química , Ouro/farmacologia , Platina/química , Platina/farmacologia , Produtos do Gene gag do Vírus da Imunodeficiência Humana/metabolismo , Complexos de Coordenação/química , Complexos de Coordenação/farmacologia , Infecções por HIV/tratamento farmacológico , HIV-1/efeitos dos fármacos , Humanos , Ligantes , Metilaminas/química , Metilaminas/farmacologia , Modelos Moleculares
19.
Dalton Trans ; 45(21): 8712-6, 2016 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-27171123

RESUMO

cis-DDP presents reactivity towards the transcription factor Sp1-F3, as opposed to previous observations for Sp1-F2. Replacing the ammine ligands with the chelating ethylenediamine increases the reactivity giving a unique dinuclear {Pt(en)}2-bis(cysteine)-bridged product, confirmed by study of the binding sequence ACPECP.


Assuntos
Complexos de Coordenação/química , Platina/química , Fator de Transcrição Sp1/química , Sequência de Aminoácidos , Complexos de Coordenação/metabolismo , Humanos , Isomerismo , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Ligação Proteica , Fator de Transcrição Sp1/metabolismo , Dedos de Zinco
20.
J Hazard Mater ; 276: 489-98, 2014 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-24929788

RESUMO

Alkanes and polycyclic aromatic hydrocarbons (PAHs) have threatened the environment due to toxicity and poor bioavailability. Interest in degradation of these hazardous materials by biosurfactant-producing bacteria has been steadily increasing in recent years. In this work, a novel biosurfactant-producing Pseudomonas sp. WJ6 was isolated to degrade a wide range of n-alkanes and polycyclic aromatic hydrocarbons. Production of lipopeptide biosurfactant was observed in all biodegradable studies. These lipopeptides were purified and identified by C18 RP-HPLC system and electrospray ionization-mass spectrometry. Results of structural analysis showed that these lipopeptides generated from different hydrocarbons were classified to be surfactin, fengycin and lichenysin. Heavy-oil sludge washing experiments demonstrated that lipopeptides produced by Pseudomonas sp. WJ6 have 92.46% of heavy-oil washing efficiency. The obtained results indicate that this novel bacterial strain and its lipopeptides have great potentials in the environmental remediation and petroleum recovery.


Assuntos
Alcanos/metabolismo , Biodegradação Ambiental , Hidrocarbonetos Policíclicos Aromáticos/metabolismo , Pseudomonas/metabolismo , Tensoativos/metabolismo
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