DESIGN
Palladium Reduction
To reduce palladium (II) compounds, a selection of palladium binding peptides derived from previous literature1,2,3,4 and were used as library peptides. The library peptides were modified with double tryptophan or tryptophan residues mutations as tryptophan has been reported to be able to reduce palladium1 and double tryptophan residues are capable of increasing the efficiency of reduction in gold5. We would like to investigate the effect of a double tryptophan structure to palladium reduction.
The following are the library peptides used in this project:
| Sequence (AA) | Reference |
|---|---|
| QQSWPIS | Chiu et al., 20101 |
| SVTQNKY | Sarikaya et al., 20031 |
| TSNAVHPTLRHL | Pacardo et al., 20094 |
| TSNAVAPTLRCL | Coppage et al., 20123 |
The following are the peptides (7 amino acids) we have designed:
| Sequence (AA) |
|---|
| QQSWGIS |
| QQWWPIS |
| QQSWWIS |
| SVTWWKY |
| SVWWNKY |
| SWWQNKY |
| WWTQNKY |
The following are the peptides (12 amino acids) we have designed:
| Sequence (AA) |
|---|
| TWWAVAPTLRCL |
| TSWWVAPTLRCL |
| TSNWWAPTLRCL |
| TSNAVAWWLRCL |
| TSNAVAPWWRCL |
| TSNAVAPTWWCL |
| TWNACAPTLRCL |
| TSWAVAPTLRCL |
| TSNWVAPTLRCL |
| TSNAWAPTLRCL |
| TSNAVWPTLRCL |
| TSNAVAWTLRCL |
| TSNAVAPWLRCL |
| TSNAVAPTWRCL |
| TSNAVAPTLWCL |
Palladium binding residues are denoted with a green colour and palldium reudcing residues are denoted with a blue colour.
Cellulose-Binding Domain (CBD)
CBD serve as the affinity tag protein for the purification of our construct. CBD binds to cellulose, which is naturally abundant, inexpensive and is an inert chemical6,7. Using a CBD as an affinity tag, we can purify our PdRp-CBD using a regenerated amorphous cellulose column as the CBD will adhere to cellulose and can be purified after washing. The low cost of cellulose enables the opportunity to the large-scale production of palladium nanoparticles. The sequence of the CBD is provided by Professor Shen-long Tsai6. CBD can also be used as a stabiliser, as it can bind to cellulose and immobilize the fusion protein7.
PdRp-CBD
The PdRp-CBD complex is formed by fusing the CBD C-terminally to the PdRp. To achieve this, an EcoRI site is placed in between. NheI and PstI are added to the 5’ and 3’ ends respectively for ligation with our vector, pETBlue-2.
PdRp-CBD construct
A CBD protein
References
[1] Y;, Chiu CY;Li Y;Huang. Size-Controlled Synthesis of Pd Nanocrystals Using a Specific Multifunctional Peptide. 2010, pubmed.ncbi.nlm.nih.gov/20648291/.
[2] Sarikaya et al. “Molecular Biomimetics: Nanotechnology through Biology.” Nature News, Nature Publishing Group, 2003, www.nature.com/articles/nmat964.
[3] Coppage, et al. “Exploiting Localized Surface Binding Effects to Enhance the Catalytic Reactivity of Peptide-Capped Nanoparticles.” Journal of the American Chemical Society, U.S. National Library of Medicine, 2013, pubmed.ncbi.nlm.nih.gov/23865951/.
[4] Pacardo, et al. “Biomimetic Synthesis of Pd Nanocatalysts for the Stille Coupling Reaction.” ACS Nano, U.S. National Library of Medicine, 2009, pubmed.ncbi.nlm.nih.gov/19422199/.
[5] DI;, Tan YN;Lee JY;Wang. Uncovering the Design Rules for Peptide Synthesis of Metal Nanoparticles. 2010, pubmed.ncbi.nlm.nih.gov/20355728/.
[6] Yunus, I. S., & Tsai, S. (2015). Designed biomolecule–cellulose complexes for palladium recovery and detoxification. RSC Advances, 5(26), 20276-20282. doi:10.1039/c4ra16200e
[7] Linder, M., Nevanen, T., Söderholm, L., Bengs, O., & Teeri, T. T. (1998). Improved immobilization of fusion proteins via cellulose-binding domains. Biotechnology and Bioengineering, 60(5), 642-647. doi:10.1002/(sici)1097-0290(19981205)60:53.0.co;2-8