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Selection of peptides binding to metallic borides by screening M13 phage display libraries.

Ploss M, Facey SJ, Bruhn C, Zemel L, Hofmann K, Stark RW, Albert B, Hauer B - BMC Biotechnol. (2014)

Bottom Line: The 7-mer peptide sequence LGFREKE, isolated on amorphous Ni3B emerged as the best binder for both substrates.Fluorescence microscopy and atomic force microscopy confirmed the specific binding affinity of LGFREKE expressing phage to amorphous and crystalline Ni3B nanoparticles.We think that the identified strong binding sequences described here could potentially serve for the utilisation of M13 phage as a viable alternative to other methods to create tailor-made boride composite materials or new catalytic surfaces by a biologically driven nano-assembly synthesis and structuring.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Technical Biochemistry, University of Stuttgart, Allmandring 31, 70569 Stuttgart, Germany. bernhard.hauer@itb.uni-stuttgart.de.

ABSTRACT

Background: Metal borides are a class of inorganic solids that is much less known and investigated than for example metal oxides or intermetallics. At the same time it is a highly versatile and interesting class of compounds in terms of physical and chemical properties, like semiconductivity, ferromagnetism, or catalytic activity. This makes these substances attractive for the generation of new materials. Very little is known about the interaction between organic materials and borides. To generate nanostructured and composite materials which consist of metal borides and organic modifiers it is necessary to develop new synthetic strategies. Phage peptide display libraries are commonly used to select peptides that bind specifically to metals, metal oxides, and semiconductors. Further, these binding peptides can serve as templates to control the nucleation and growth of inorganic nanoparticles. Additionally, the combination of two different binding motifs into a single bifunctional phage could be useful for the generation of new composite materials.

Results: In this study, we have identified a unique set of sequences that bind to amorphous and crystalline nickel boride (Ni3B) nanoparticles, from a random peptide library using the phage display technique. Using this technique, strong binders were identified that are selective for nickel boride. Sequence analysis of the peptides revealed that the sequences exhibit similar, yet subtle different patterns of amino acid usage. Although a predominant binding motif was not observed, certain charged amino acids emerged as essential in specific binding to both substrates. The 7-mer peptide sequence LGFREKE, isolated on amorphous Ni3B emerged as the best binder for both substrates. Fluorescence microscopy and atomic force microscopy confirmed the specific binding affinity of LGFREKE expressing phage to amorphous and crystalline Ni3B nanoparticles.

Conclusions: This study is, to our knowledge, the first to identify peptides that bind specifically to amorphous and to crystalline Ni3B nanoparticles. We think that the identified strong binding sequences described here could potentially serve for the utilisation of M13 phage as a viable alternative to other methods to create tailor-made boride composite materials or new catalytic surfaces by a biologically driven nano-assembly synthesis and structuring.

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Evaluation of the binding strength of each of the 42 identified phage clones. The relative binding affinity of the phage clones to amorphous (A) and crystalline (B) Ni3B nanoparticles was determined by titer assays at pH 7. The assay was repeated three-times for each clone and the elucidated phage amounts were arithmetically averaged. As a control, M13KE wild-type (M13wt) phage without a random peptide insert were compared in the same manner as the phage clones. Strong binding phage clones (> 109 pfu/ml) are indicated with an arrow. Clones identified on amorphous Ni3B are designated with an A, clones identified on crystalline Ni3B are designated with a C.
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Figure 2: Evaluation of the binding strength of each of the 42 identified phage clones. The relative binding affinity of the phage clones to amorphous (A) and crystalline (B) Ni3B nanoparticles was determined by titer assays at pH 7. The assay was repeated three-times for each clone and the elucidated phage amounts were arithmetically averaged. As a control, M13KE wild-type (M13wt) phage without a random peptide insert were compared in the same manner as the phage clones. Strong binding phage clones (> 109 pfu/ml) are indicated with an arrow. Clones identified on amorphous Ni3B are designated with an A, clones identified on crystalline Ni3B are designated with a C.

Mentions: Because of the heterogeneity of all of the identified binding peptides and the absence of a distinctive binding motif, the binding strength of each of the 42 identified peptides to amorphous (Figure 2A) and crystalline (Figure 2B) Ni3B was determined by titer assays. Since previously binding affinity experiments at pH 5 or pH 9 with a subset of the identified binding peptides showed no increase in binding affinity (data not shown) the relative binding affinity experiments were carried out at pH 7. As a control to verify that the peptide was the interactor of interest, M13KE wild-type (M13wt) phage without a random peptide insert were compared in the same manner as the peptide clones. As presented in Figure 2A, most of the phage clones, except C2 and C17, bind to amorphous Ni3B with greater affinity than does the M13wt phage, which shows a binding affinity of 2 × 107 pfu/ml with amorphous Ni3B. Compared with the M13wt phage, 9 out of 42 identified peptides (see arrows in Figure 2A) bound on average 100-times and 28 on average ten-times more efficiently to amorphous Ni3B than the wild-type, verifying that binding to the substrate was a result of the peptide sequence and not due to non-specific phage coat protein interactions. The peptides A7, C12, and C15 (see arrows in Figure 2B) bound on average 1000-times more efficiently to crystalline Ni3B as compared to the M13wt phage, which shows a binding affinity of 5 × 106 pfu/ml. Interestingly, the phage clone A7 identified for amorphous Ni3B shows a higher binding affinity to crystalline Ni3B than most of the Ni3B-binding peptides (C1-C11, C13-C14, and C16-C28) identified for crystalline Ni3B. In addition, the amorphous Ni3B-binding peptides A8-A10 show a higher binding affinity to crystalline Ni3B (≥109 pfu/ml) than several binding peptides found for crystalline Ni3B specifically (i.e. C1-C11, C13-C14, C16-C24, and C27-28). The relative binding affinity experiments revealed a set of several strong binders (>109 pfu/ml) for amorphous (A1-A3, A7, C4, C9, C13, C15, and C24) and crystalline (A7, C12, and C15) substrates (Table 4). The phages displaying the peptides A7 and C15 emerged as the best binders for both substrates.


Selection of peptides binding to metallic borides by screening M13 phage display libraries.

Ploss M, Facey SJ, Bruhn C, Zemel L, Hofmann K, Stark RW, Albert B, Hauer B - BMC Biotechnol. (2014)

Evaluation of the binding strength of each of the 42 identified phage clones. The relative binding affinity of the phage clones to amorphous (A) and crystalline (B) Ni3B nanoparticles was determined by titer assays at pH 7. The assay was repeated three-times for each clone and the elucidated phage amounts were arithmetically averaged. As a control, M13KE wild-type (M13wt) phage without a random peptide insert were compared in the same manner as the phage clones. Strong binding phage clones (> 109 pfu/ml) are indicated with an arrow. Clones identified on amorphous Ni3B are designated with an A, clones identified on crystalline Ni3B are designated with a C.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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Figure 2: Evaluation of the binding strength of each of the 42 identified phage clones. The relative binding affinity of the phage clones to amorphous (A) and crystalline (B) Ni3B nanoparticles was determined by titer assays at pH 7. The assay was repeated three-times for each clone and the elucidated phage amounts were arithmetically averaged. As a control, M13KE wild-type (M13wt) phage without a random peptide insert were compared in the same manner as the phage clones. Strong binding phage clones (> 109 pfu/ml) are indicated with an arrow. Clones identified on amorphous Ni3B are designated with an A, clones identified on crystalline Ni3B are designated with a C.
Mentions: Because of the heterogeneity of all of the identified binding peptides and the absence of a distinctive binding motif, the binding strength of each of the 42 identified peptides to amorphous (Figure 2A) and crystalline (Figure 2B) Ni3B was determined by titer assays. Since previously binding affinity experiments at pH 5 or pH 9 with a subset of the identified binding peptides showed no increase in binding affinity (data not shown) the relative binding affinity experiments were carried out at pH 7. As a control to verify that the peptide was the interactor of interest, M13KE wild-type (M13wt) phage without a random peptide insert were compared in the same manner as the peptide clones. As presented in Figure 2A, most of the phage clones, except C2 and C17, bind to amorphous Ni3B with greater affinity than does the M13wt phage, which shows a binding affinity of 2 × 107 pfu/ml with amorphous Ni3B. Compared with the M13wt phage, 9 out of 42 identified peptides (see arrows in Figure 2A) bound on average 100-times and 28 on average ten-times more efficiently to amorphous Ni3B than the wild-type, verifying that binding to the substrate was a result of the peptide sequence and not due to non-specific phage coat protein interactions. The peptides A7, C12, and C15 (see arrows in Figure 2B) bound on average 1000-times more efficiently to crystalline Ni3B as compared to the M13wt phage, which shows a binding affinity of 5 × 106 pfu/ml. Interestingly, the phage clone A7 identified for amorphous Ni3B shows a higher binding affinity to crystalline Ni3B than most of the Ni3B-binding peptides (C1-C11, C13-C14, and C16-C28) identified for crystalline Ni3B. In addition, the amorphous Ni3B-binding peptides A8-A10 show a higher binding affinity to crystalline Ni3B (≥109 pfu/ml) than several binding peptides found for crystalline Ni3B specifically (i.e. C1-C11, C13-C14, C16-C24, and C27-28). The relative binding affinity experiments revealed a set of several strong binders (>109 pfu/ml) for amorphous (A1-A3, A7, C4, C9, C13, C15, and C24) and crystalline (A7, C12, and C15) substrates (Table 4). The phages displaying the peptides A7 and C15 emerged as the best binders for both substrates.

Bottom Line: The 7-mer peptide sequence LGFREKE, isolated on amorphous Ni3B emerged as the best binder for both substrates.Fluorescence microscopy and atomic force microscopy confirmed the specific binding affinity of LGFREKE expressing phage to amorphous and crystalline Ni3B nanoparticles.We think that the identified strong binding sequences described here could potentially serve for the utilisation of M13 phage as a viable alternative to other methods to create tailor-made boride composite materials or new catalytic surfaces by a biologically driven nano-assembly synthesis and structuring.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Technical Biochemistry, University of Stuttgart, Allmandring 31, 70569 Stuttgart, Germany. bernhard.hauer@itb.uni-stuttgart.de.

ABSTRACT

Background: Metal borides are a class of inorganic solids that is much less known and investigated than for example metal oxides or intermetallics. At the same time it is a highly versatile and interesting class of compounds in terms of physical and chemical properties, like semiconductivity, ferromagnetism, or catalytic activity. This makes these substances attractive for the generation of new materials. Very little is known about the interaction between organic materials and borides. To generate nanostructured and composite materials which consist of metal borides and organic modifiers it is necessary to develop new synthetic strategies. Phage peptide display libraries are commonly used to select peptides that bind specifically to metals, metal oxides, and semiconductors. Further, these binding peptides can serve as templates to control the nucleation and growth of inorganic nanoparticles. Additionally, the combination of two different binding motifs into a single bifunctional phage could be useful for the generation of new composite materials.

Results: In this study, we have identified a unique set of sequences that bind to amorphous and crystalline nickel boride (Ni3B) nanoparticles, from a random peptide library using the phage display technique. Using this technique, strong binders were identified that are selective for nickel boride. Sequence analysis of the peptides revealed that the sequences exhibit similar, yet subtle different patterns of amino acid usage. Although a predominant binding motif was not observed, certain charged amino acids emerged as essential in specific binding to both substrates. The 7-mer peptide sequence LGFREKE, isolated on amorphous Ni3B emerged as the best binder for both substrates. Fluorescence microscopy and atomic force microscopy confirmed the specific binding affinity of LGFREKE expressing phage to amorphous and crystalline Ni3B nanoparticles.

Conclusions: This study is, to our knowledge, the first to identify peptides that bind specifically to amorphous and to crystalline Ni3B nanoparticles. We think that the identified strong binding sequences described here could potentially serve for the utilisation of M13 phage as a viable alternative to other methods to create tailor-made boride composite materials or new catalytic surfaces by a biologically driven nano-assembly synthesis and structuring.

Show MeSH