Dendrimer Conjugated Antifreeze Peptides: Synthesis, Characterisation and Antifreeze Activity Studies

ResearchSpace/Manakin Repository

Show simple item record

dc.contributor.advisor Sarojini, V en
dc.contributor.author Sharma, Anuvratta en
dc.date.accessioned 2018-06-05T01:10:50Z en
dc.date.issued 2018 en
dc.identifier.uri http://hdl.handle.net/2292/37201 en
dc.description Full text is available to authenticated members of The University of Auckland only. en
dc.description.abstract Antifreeze proteins (AFPs) are capable of modifying ice crystal morphology and noncolligatively depressing the freezing point of water; these unique features of AFPs have potential applications in various biotechnological fields. Linking these AFPs to dendrimer cores has previously shown significant improvement in antifreeze activity, and with careful tailoring, has great commercial potential in these fields. This thesis describes the design, synthesis and evaluation of antifreeze activity of dendrimer-linked AFPs. The first part of this thesis describes the design and synthesis of dendrimer-linked AFPs. Short AFP analogues and dendrimer cores were synthesised via solid phase peptide synthesis and purified to >95% purity. Cysteinylated AFPs were linked to maleimide-functionalised dendrimer cores via a thioether bond, and monitored using analytical RP-HPLC and mass spectrometry. The second part of this thesis describes the evaluation of antifreeze activity and solution conformation of AFP analogues and dendrimer-linked AFPs. The lactam-bridge modified analogue (13cyc) of a previously inactive AFP (DCR13) did not possess antifreeze activity. However, the di-branched conjugate of 13cyc (Di13cyc), possessed both ice-shaping and thermal hysteresis (TH) activity, further reinforcing previous findings that a minimum sequence length is crucial for antifreeze activity. In the case of the DCR series of sequence minimised AFP analogues (derived from the AFP produced by the insect Dendroides canadensis), two repeats of an intra-coil bridge is required. All dendrimer-linked analogues demonstrated low levels of TH activity, and ice crystal shaping into thin, hexagonal plates; this morphology is distinctly different to the rice-grain shaped ice crystals observed with previously designed 26- and 39-mer analogues. Ice crystal ‘burst’ patterns demonstrated by 26-mer multimers were observed occurring normal to the c-axis, a characteristic seen only in hyperactive AFPs, and is thought to be the key feature for hyperactivity. These findings suggest that the DCR family of dendrimers synthesised in this thesis have the potential to exhibit hyperactivity at higher levels of branching. Solution conformations of AFP analogues and dendrimer-linked AFPs performed with circular dichroism (CD) spectroscopy showed random coil conformations in phosphate buffer alone, and α-helical conformations in 50% trifluoroethanol (TFE) buffer; the 26-mer analogues possessed slightly more α-helical character than 13-mer analogues. Based on the results presented in this thesis, dendrimer-linked AFPs with tailored AFP monomers have the potential to become a commercially available product for various applications with further development. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof Masters Thesis - University of Auckland en
dc.relation.isreferencedby UoA99265062413002091 en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights Restricted Item. Available to authenticated members of The University of Auckland. en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.title Dendrimer Conjugated Antifreeze Peptides: Synthesis, Characterisation and Antifreeze Activity Studies en
dc.type Thesis en
thesis.degree.discipline Chemistry en
thesis.degree.grantor The University of Auckland en
thesis.degree.level Masters en
dc.rights.holder Copyright: The author en
pubs.elements-id 742409 en
pubs.record-created-at-source-date 2018-06-05 en


Full text options

This item appears in the following Collection(s)

Show simple item record

Share

Search ResearchSpace


Advanced Search

Browse