It is well known that the structure of proteins determines its function.The two disulfide bond plays an important role in the folding and assembly of a structure with biological activity, and stability of this structure(Especially in containing more than one subunit protein or polypeptide).Disulfide bond formation protein A(DsbA) is folded enzyme catalyzed two sulfur bond formation in Escherichia coli periplasm cavity in a nascent protein folding process.It can greatly improve the folding rate of the nascent peptide chain, thus enabling Escherichia coli to ensure that the nascent polypeptide chains can be folded in a timely and correct fashion.
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Lpp-OmpA-mbp(lead) is designed as a fusion protein consisting of the signal sequence and first 9 amino acid of Lpp, residue 46~159 of OmpA and the metal binding peptide(MBP), which functions as the surface display part to bind lead in the water. The signal peptide of the N-termini of this fusion protein targets the protein on the membrane while the trans-membrane domain of OmpA serves as an anchor. MBP is on the externally exposed loops of OmpA, which can be anchored to the outer membrane.
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DsbA is the first protein found in the Dsb family.It consists of 208 amino acids, and has a C terminal signal peptide of 19 amino acids.It has an active central structure.The process of the formation and reduction of two sulfur bonds is achieved by exchanging sulfhydryl and two sulfur bonds between the active sites and the sulfhydryl or two sulfur bonds of the target proteins.(Thompson JD，Gibson TJ，Piewniak F，et a1．The ClustalX windows interface：flexible strategies for multiple sequence alignment aided by quality analysis tools．Nucleic Acids Research,1997,24:4876 -4882.)
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DsbA has a stronger oxidation than Thioredoxin.Experiments have shown that its strong oxidation comes from Cys30 residues with abnormally low pKa and unstable oxidation structure.(Zapun A,Cooper L,Creighton TE.Replacement of the active-site cysteine residues of DsbA,a protein required for disulfide bond formation in vivo.Biochemistry,1994,33:1907-1914.)Also,experimental results show that DsbA can improve the efficiency of protein folding in intracellular and extracellular.
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Revision as of 09:20, 21 October 2017
Lpp-OmpA-MBP(Pb)
Lpp-OmpA-mbp(lead) is designed as a fusion protein consisting of the signal sequence and first 9 amino acid of Lpp, residue 46~159 of OmpA and the metal binding peptide(MBP), which functions as the surface display part to bind lead in the water. The signal peptide of the N-termini of this fusion protein targets the protein on the membrane while the trans-membrane domain of OmpA serves as an anchor. MBP is on the externally exposed loops of OmpA, which can be anchored to the outer membrane.
