No abstract

DNA sequencing using nanopores has already been achieved and commercialized; the next step in advancing nanopore technology is towards protein sequencing. Although trials have been reported for discriminating the 20 amino acids using biological nanopores and short peptide carriers, it remains challenging. The size compatibility between nanopores and peptides is one of the issues to be addressed. Therefore, exploring biological nanopores that are suitable for peptide sensing is key in achieving amino acid sequence determination. Here, we focus on EXP2, the transmembrane protein of a translocon from malaria parasites, and describe its pore‐forming properties in the lipid bilayer. EXP2 mainly formed a nanopore with a diameter of 2.5 nm assembled from 7 monomers. Using the EXP2 nanopore allowed us to detect poly‐L‐lysine (PLL) at a single‐molecule level. Furthermore, the EXP2 nanopore has sufficient resolution to distinguish the difference in molecular weight between two individual PLL, long PLL (Mw: 30,000–70,000) and short PLL (Mw: 10,000). Our results contribute to the accumulation of information for peptide‐detectable nanopores.

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The concentration of protein in honey is lower than polysaccharide. However, recently the honey's protein is intensively studied and it showed that protein also have several biological activities such as antibacterial activity. The purpose of this research is to isolate and characterize Tetragonula laeviceps honey protein by determining the molecular weight. Honey protein of Trigona laeviceps was isolated using ultra-filtration with the membrane's size of 30 kDa, then concentrated using tube membrane size 10 kDa. Molecular weight was analyzed by SDS PAGE. From the analysis, there was major protein band in honey produced by Tetragona laeviceps identified. The produced molecular weight of major protein bands were about 87 and 65 kDa. Determining of the molecular weight of this protein could be used to detect the originality of Tetragonula laeviceps honey from Indonesia. AbstrakIsolasi dan Karakterisasi Berat Molekul Protein Madu dari Tetragonula laeviceps. Konsentrasi protein dalam madu sangat rendah dibandingkan dengan polisakarida. Namun, belakangan waktu ini protein madu secara intensif diteliti dan menunjukkan bahwa protein madu juga memiliki beberapa aktvitas biologi yaitu aktivitas antibakteri. Tujuan dari penelitian ini adalah untuk mengisolasi dan mengkarakterisasi protein yang berasal dari madu Tetragonula laeviceps dengan menentukan berat molekul. Protein dari madu Tetragonula laeviceps diisolasi menggunakan ulltrafitrasi dengan penambahan gas N 2 (ukuran membrane 30 kDa). Berat molekul protein dianalisis dengan menggunakan SDS PAGE. Dari hasil analisis, didapatkan band major protein dalam madu Tetragona laeviceps. Berat molekul dari major protein adalah 87 dan 65 kDa. Penentuan berat molekul dapat berguna untuk mendeteksi originalitas madu Tetragonu laevices dari Indonesia.

Plasmodium falciparum parasitophorous vacuolar protein 1 (PfPV1), a protein unique to malaria parasites, is localized in the parasitophorous vacuolar (PV) and is essential for parasite growth. Previous studies suggested that PfPV1 cooperates with the Plasmodium translocon of exported proteins (PTEX) complex to export various proteins from the PV. However, the structure and function of PfPV1 have not been determined in detail. In this study, we undertook the expression, purification, and characterization of PfPV1. The tetramer appears to be the structural unit of PfPV1. The activity of PfPV1 appears to be similar to that of molecular chaperones, and it may interact with various proteins. PfPV1 could substitute CtHsp40 in the CtHsp104, CtHsp70, and CtHsp40 protein disaggregation systems. Based on these results, we propose a model in which PfPV1 captures various PV proteins and delivers them to PTEX through a specific interaction with HSP101.