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Biomol NMR Assign ; 2021 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-34091855


Emfourin (M4in) from Serratia proteamaculans is a new proteinaceous inhibitor of protealysin-like proteases (PLPs), a subgroup of the well-known and widely represented metallopeptidase M4 family. Although the biological role of PLPs is debatable, data published indicate their involvement in pathogenesis, including bacterial invasion into eukaryotic cells, suppression of immune defense of some animals, and destruction of plant cell walls. Gene colocalization into a bicistronic operon observed for some PLPs and their inhibitors (as in the case of M4in) implies a mutually consistent functioning of both entities. The originality of the amino acid sequence of M4in suggests it belongs to a previously unknown protein family and this encourages structural studies. In this work, we report a near-complete assignment of 1H, 13C, and 15N resonances of recombinant M4in and its structural-dynamic properties derived from the chemical shifts. According the NMR data analysis, the M4in molecule comprises 3-5 helical elements and 4-6 ß-strands, at least two of which are apparently antiparallel, ascribing this obviously globular protein to the α + ß structural class. Besides, two disordered regions also exist in the central loops between the regular secondary structural elements. The obtained data provide the basis for determining the high-resolution structure as well as functioning mechanism of M4in that can be used for development of new antibacterial therapeutic strategies.

Dalton Trans ; 50(18): 6245-6255, 2021 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-33876177


Reaction of (2,3,9,10,16,17,23,24-octabutylphthalocyaninato)lanthanide(iii) acetylacetonates (BuPcLn(acac), 1a-c, Ln = Lu (a), Eu (b), La (c)) with a tetrakis(5,7-bis(4-tert-butylphenyl)-6H-1,4-diazepino)[2,3-b,g,l,q]porphyrazine ligand (tBuPhDzPzH2, 2) produced sandwich compounds (tBuPhDzPz)Ln(BuPc) (3a-c), which represent the first heteroleptic double-deckers incorporating both Pc and DzPz decks. A combination of high-resolution mass spectrometry, UV-Vis/NIR, MCD, and 1H NMR spectroscopy, and square-wave voltammetry provided unambiguous characterization of target complexes 3 indicating that their spectral and electrochemical properties are generally intermediate with respect to their homoleptic relatives. Based on the data of solution-state 1H-1H NMR (COSY, NOESY) correlation spectroscopy supported by DFT calculations, a dimerization tendency of compounds 3 proportional to the Ln(iii) ion size was found. The spectroelectrochemical study of 3 and the corresponding homoleptic double-deckers revealed a pronounced tendency to aggregation of the one-electron oxidized forms of DzPz-containing double-decker complexes compared to homoleptic Pc2Ln compounds.

J Mass Spectrom ; 56(5): e4723, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33813767


A laser plasma ion source was used to ionize volatile organic compounds in a gas sample. The plasma was generated on a metal target in the intermediate vacuum region of ~0.3 Torr using a pulsed Nd:YAG laser with a wavelength of 1 µm. The resulting ions mass spectra were acquired using orthogonal time-of-flight mass spectrometer (O-TOF MS). When using a copper target, the ions formed are simple complexes (CuM+ ) of copper ions with organic molecules. The possibility of online identification of trace amounts of alkanes in nitrogen and air, with a detection limit of ~10 ppb, was demonstrated. The ionization efficiency of volatile organic compounds through the formation of clusters with metal ions is 10-4 in terms of the quasimolecular complex ions. The rate constants of ion-molecular reactions of copper ions with octane and water molecules in nitrogen and air are estimated.