Dr Viji Sarojini
PhD (Indian Institute of Science, Bangalore and BHU)
- PhD. BHU, Varanasi & IISc. Bangalore, India (with Prof. R.B.Rao & Prof P. Balaram)
Non-protein Amino Acids in Peptide Design
- Post-doctoral Research Fellow, Linkoping University, Sweden (with Prof Lars Baltzer).
Control of Folding and Function in Synthetic Polypeptides and Glycopeptides
- Research Fellow, University of Leeds, Leeds, UK
Synthetic Peptides to study Membrane-Protein Interactions
- Research Associate, Texas A&M University, Texas, USA
Analysis of post-trastional modifications in Human Toll-Like Receptor Protein 3 (hTLR-3)
- Post-doctoral Research Scientist, HortResearch, Auckland, New Zealand
Antibacterial Peptides against Fire Blight of Pome Fruits
Research | Current
Food, Drug, Health Peptides (FDHP)
Peptides are an initeresting class of molecules with applications in agriculture, biology, medicine, food and material sciences. Peptides have evolved in nature to take on highly spcific functions, have great potency and are much smaller than recombinant proteins and antibodies. The filed of therapeutic peptides is undergoing a very exciting revival owing to substances technological progresses during the last decade.
Peptide-macromolecular interactions modulate several biological functions. The development of biologically active peptides is an area of immense research interest. However, inherent conformational flexibility and susceptibility to proteases are two major drawbacks that limit the use of peptides made up of the twenty protein amino acids as drugs. Backbone and side-chain modifications are used as a means of controlling conformational flexibility and protease stability in the design of biologically active peptides and synthetic mimics of protein structures. The major focus of my research is the denovo design, synthesis and structure activity studies of bioactive peptides.
We use Solid Phase Peptide Synthesis following Fmoc- chemistry as well as conventional solution phase peptide synthesis procedures. The peptide sequences are tailor made from naturally occurring proteins. Polypeptide Modelling software is made use of for this purpose. Structure-activity studies of the synthetic peptides are carried out in order to optimise the structure for specific applications.
Nuclear Magnetic Resonance (NMR) and Circular Dichroism (CD) are used to elucidate the secondary structure of synthetic peptides. Of particular interest to the group are
- Antimicrobial Peptides against Multi Drug Resistant (MDR) Biofilms
- Antifreeze Peptides for Frozen Food Preservation
- Multifunctional Anticancer Peptides with increased tumor selectivity
- Cell Penetrating Peptides for Drug Delivery
- Polypeptide Biosensors
- Self-assembling Peptides
- Non-protein amino acids in Peptide Design
- Synthetic strategies for novel linear and cyclc lipopeptides
Mapping the Meat Peptidome: Meat Quality Biomarkers (collaboration with AgResearch)
This project aims to unlock the nutritional potential of proteins in red meat and capture these for wider application in foods beyond traditional dishes. Research in this area involves collaboration with a group of meat scientists to support the creation of protein-rich functional foods for consumers having optimized nutritional composition and physiological benefits and export of high-value meat based ingredients for manufacturers. Biomarker identification is achieved through the use of advanced proteomics technology and database mapping.
- Targeted Anticancer Peptides (Collaboration with Auckland Cancer Society Research Centre)
Through this project, we aim to develop the fundamentals of selective anticancer chemotherapy using peptides as targeting moieties. Multifunctional peptides incorporating novel and advanced design features with the potential to realize enhanced tumor selectivity and potency are being developed in a multi-disciplinary collaboration with Ditinguished Professor Bill Denny (ACSRC) and the School of Pharmacy. Anticancer Peptide conjugated liposomes are used for enhanced cellular internalization. General properties of peptide grafted liposome nanoparticles are studied.
- Antimicrobial Peptides against Multi Drug Resitant Biofilms
Biofilms are matrix-embedded microorganisms adhering to biotic and abiotic surfaces including human tissues and are impervious to drugs. Biofilm forming bacteria exhibit multiple drug resistance (MDR) and this phenomenon is becoming increasingly prevalent amongst human, animal and plant pathogens. Infections from bacterial biofilms cause high health costs as well as economic loss in agriculture. Our screening program last year identified peptide based structures that reduce the formation of biofilms in certain bacterial species. Further research is being carried out to explore the mechanism of action of these lead molecules and elucidate their Structure Activity Relationships. This research has significant implications in the treatment of chronic infections such as those caused by Pseudomonas aeruginosa in cystic fibrosis patients because existing antibiotic therapy has not been successful in killing bacterial biofilms, the most common cause of persistent infections.
- Antifreeze Peptides: Frozen Food Industry Applications
Synthetic peptide analogues of naturally occuurring Anti-Freeze Proteins (AFPs) are studied to better understand their function and potential in frozen food applications. Naturally occurring AFPs exhibit properties of ice-recrystalization inhibition. The ability of AFPs to influenze the size, morphology and aggregation of ice crystals can be used in food technology where the growth of ice crystals in frozen foods is of primary concern. This project is carried out in collaboration with the Food Science Group at UoA.
- Protein Based Medical Adhesives
Medical adhesives form an important component of the surgical toolbox and provide an interesting area for research and development. Naturally occurring adhesive proteins have attracted the attention of scientists due to their incredible adhesive strength and biocompatibility. In this project we aim to synthetise short adhesive peptides and study their adhesive properties to various surfaces like medically relevant metals, teflon and other plastic under different temperatures and moisture conditions. Atomic Force Microscopy (AFM) as well as fatigue failure test will be used to evaluate the binding force between the adhesive and the surface. Applications of these peptides include embedding antibiotics into the adhesive to prevent surface colonisation of medical implants by bacteria well as its potential as a surgical sealant for wound closure. This project is done in collaboration is done in collaboration with Faculty of Engineering, UoA.
- Branched Peptide Therapeutics
The concept of a ‘Magic Bullet’ coined by Paul Elrich a century ago can now be attributed to target specific molecules like peptides. Modern day technologies, especially the combinatorial synthesis and screening of peptides, have resulted in the development of dozens of peptides as clinical trial candidates for various diseases. Despite this, there still exists some industrial reluctance to use peptides as drugs, mainly because of their short half-lives. Branched peptides exhibit strong resistance to proteases and are hence suitable candidates for the development of peptide based drugs. I am interested in developing synthetic proteins with a branched structure. An ongoing project in this direction makes use of Native Chemical Ligation to stitch together a pore forming peptide to a designed helix.
- Development of Peptide Antibiotics for Fire Blight and Bacterial Canker of Kiwi Fruit
This project aims to develop antimicrobial peptides with potency against PSA of Kiwi Gold and Fire Blight of pome fruits in a cost-effective manner. Our strategy focusses on tailoring large polypeptides into shorter sequences and developing novel antimicrobial peptides which are simple to synthesize in a cost-effective manner. This is achieved through rational design, synthesis and bioassay guided analysis.
- DNA Binding Peptides Targetting Type III Secretion Pathway in the Fire Blight Pathogen, Erwinia amylovora (Collaboration with Plant and Food Research)
Erwinia amylovora is a biofilm forming Gram negative bacterium that causes Fire Blight of apple and pear. Fire Blight results in severe economic loss to apple and pear orchardists in New Zealand and several other parts of the world with no effective chemicals for prevention or cure especially because of resistance to streptomycin by the pathogen. The development of new compounds capable of combating this disease is timely and is of particular interest to the NZ apple industry. An ongoing project in my research group is focused on developing novel peptide based structures as chemical control options for Fire Blight. Gram negative bacteria use the Type III Secretion System (TTSS) to synthesise ‘Hrp proteins’ and infect the host. Harpins, the virulent proteins secreted by TTSS of E.amylovora, induce rapid changes in plant cell metabolism thus leading to plant cell death. Mutations in the TTSS gene have been shown to make these bacteria less virulent. Our research aims to develop synthetic peptides with DNA binding ability that can be targeted to specific sites of the TTSS gene of E.amylovora and inactivate it.
- Mimics of Ina Protein: Explolring Surface Frost Damage in Plants, Pseudomonas Syringae as a Model
Phytotoxins are products of plant pathogens or of host-pathogen interactions that directly injure plant cells and cause disease development. Pseudomonas syringae is one such phytopathogenic bacterium that infects a wide range of plant species including the kiwi fruit. In addition to the production of phytotoxins, this bacterium is also characterized by ice nucleation activity through the production of ‘Ina proteins’ which causes severe frost damages in plants, especially when sudden decrease of temperature occurs. Recent outbreak of the bacterial canker that hit the kiwi gold orchards in Italy was caused by P.syringae. We aim to develop synthetic peptide analogues of the ‘Ina proteins' of P.syringae to study their ice nucleation properties.
- Use of non-protein amino acids in protein design
The use of non-protein amino acids to enhance the in vivo stability of biologically active peptides is another area of research I am interested in. We make use of alpha,alpha-dialkylated amino acids to promote specific secondary structures and folding in designed biologically active peptides.
Teaching | Current
CHEM 230 Molecules for Life: Synthesis and Reactivity
CHEMMAT 242 Applied Chemistry
CHEM 260 Introduction to Green Chemistry
CHEM 360 Contemporary Green Chemistry
CHEM 390 Medicinal Chemistry (Course Coordinator)
CHEM 392 Issues in Drug Design and Development (Course Coordinator)
CHM 750 Advanced Topics in Chemistry
Gayan Heruka DeZoysa
Chair of Post Graduate Committee, School of Chemical Sciences
Areas of expertise
- Peptide Chemistry
- Biological Chemistry
New Zealand Institute of Chemistry, Auckland Branch
European Peptide Society
New Zealand Institute of Chemistry
International Horticultural Society
Selected publications and creative works (Research Outputs)
- Cameron, A. J., Varnava, K. G., Edwards, P. J. B., Harjes, E., & Sarojini Amma, V. (2018). Acyclic peptides incorporating the d-Phe-2-Abz turn motif: Investigations on antimicrobial activity and propensity to adopt β-hairpin conformations. Journal of Peptide Science, 1-10. 10.1002/psc.3094.
- De Zoysa, G. H., Glossop, H. D., & Sarojini, V. (2018). Unexplored antifungal activity of linear battacin lipopeptides against planktonic and mature biofilms of C. albicans. European journal of medicinal chemistry, 146, 344-353. 10.1016/j.ejmech.2018.01.023
Other University of Auckland co-authors: Heru De Zoysa
- Glossop, H. D., Pearl, E., De Zoysa, G. H., & Sarojini, V. (2018). Linear Analogues of the Lipopeptide Battacin With Potent In Vitro Activity Against S. aureus. In R. Donev (Ed.) (pp. 385-394). ELSEVIER ACADEMIC PRESS INC. 10.1016/bs.apcsb.2018.03.004
Other University of Auckland co-authors: Heru De Zoysa
- Cameron, A. J., Edwards, P. J. B., Harjes, E., & Sarojini, V. (2017). Tyrocidine a analogues bearing the planar d-Phe-2-Abz turn motif: How conformation impacts bioactivity. Journal of Medicinal Chemistry, 60 (23), 9565-9574. 10.1021/acs.jmedchem.7b00953
Other University of Auckland co-authors: Alan Cameron
- Cameron, A. J., Squire, C. J., Edwards, P. J., Harjes, E., & Sarojini, V. (2017). Crystal and NMR structures of a peptidomimetic β-turn that provides facile synthesis of 13-membered cyclic tetrapeptides. Chemistry - An Asian Journal, 12 (24), 3195-3202. 10.1002/asia.201701422
Other University of Auckland co-authors: Christopher Squire, Alan Cameron
- Cho, C. A. H., Liang, C., Perera, J., Liu, J., Varnava, K. G., Sarojini, V., ... Swift, S. (2017). Molecular weight and charge density effects of guanidinylated biodegradable polycarbonates on antimicrobial activity and selectivity. Biomacromolecules, 19 (5), 1389-1401. 10.1021/acs.biomac.7b01245
Other University of Auckland co-authors: Jianyong Jin, Duncan McGillivray, Ralph Cooney, Simon Swift, Margaret Brimble
- Rajchakit, U., & Sarojini, V. (2017). Recent Developments in Antimicrobial-Peptide-Conjugated Gold Nanoparticles. Bioconjugate chemistry, 28 (11), 2673-2686. 10.1021/acs.bioconjchem.7b00368
Other University of Auckland co-authors: Urawadee Rajchakit
- Kong, C. H., Hamid, N., Ma, Q., Lu, J., Wang, B.-G., & Sarojini, V. (2017). Antifreeze peptide pretreatment minimizes freeze-thaw damage to cherries: An in-depth investigation. LWT - Food Science and Technology, 84, 441-448. 10.1016/j.lwt.2017.06.002