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Type: Artigo
Title: Primary structure of a trypsin inhibitor (Copaifera langsdorffii trypsin inhibitor-1) obtained from C. Langsdorffii seeds
Author: Silva, josé A.
Pompeu, Dávia G.
Smolka, Marcus B.
Gozzo, Fabio C.
Comar Jr, Moacyr
Eberlin, Marcos N.
Granjeiro, Paulo A.
Marangoni, Sérgio
Abstract: In this study, the aim was to determine the complete sequence of the Copaifera langsdorffii trypsin inhibitor (CTI)-1 using 2-dimensional (2D)-PAGE, matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF), and quadrupole time-of-flight (QTOF) spectrometry. Spots A (CTI-1) and F (CTI-2) were submitted to enzymatic digestions with trypsin, SV8, and clostripain. The accurate mass of the peptide obtained from each digest was determined by mass spectrometry (MS) using MALDI-TOF. The most abundant peptides were purified and sequenced in a liquid chromatograph connected to an electrospray ionization-QTOF MS. When the purified trypsin inhibitor was submitted to 2D electrophoresis, different spots were observed, suggesting that the protein is composed of 2 subunits with microheterogeneity. Isoelectric points of 8.0, 8.5, and 9.0 were determined for the 11 kDa subunit and of 4.7, 4.6, and 4.3 for the 9 kDa subunit. The primary structure of CTI-1, determined from the mass of the peptide of the enzymatic digestions and the sequence obtained by MS, indicated 180 shared amino acid residues and a high degree of similarity with other Kunitz (KTI)-type inhibitors. The peptide also contained an Arg residue at the reactive site position. Its 3-dimensional structure revealed that this is because the structural discrepancies do not affect the canonical conformation of the reactive loop of the peptide. Results demonstrate that a detailed investigation of the structural particularities of CTI-1 could provide a better understanding of the mechanism of action of these proteins, as well as clarify its biologic function in the seeds. CTI-1 belongs to the KTI family and is composed of 2 polypeptide chains and only 1 disulfide bridge.
Subject: Inibidores da tripsina
Espectrometria de massa com ionização por eletrospray
Eletroforese bidimensional
Espectrometria de massas por ionização e dessorção a laser assistida por matriz
Country: Estados Unidos
Editor: The Association of Biomolecular Resource Facilities
Citation: Journal Of Biomolecular Techniques : Jbt. v. 26, n. 3, p. 90-102, 2015-Sep.
Rights: fechado
Identifier DOI: 10.7171/jbt.15-2603-002
Date Issue: 2015
Appears in Collections:IQ - Artigos e Outros Documentos
IB - Artigos e Outros Documentos

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