C1, SAP and ZiCo: structural studies of three metal‑binding proteins from a crystallographic perspective

Fallas, Andrea Jennifer (2011) C1, SAP and ZiCo: structural studies of three metal‑binding proteins from a crystallographic perspective. Doctoral thesis (DPhil), University of Sussex.

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Abstract

Atomic resolution models of proteins are crucial for understanding their biological
mechanisms and provide insights into the relationship between protein sequence and
structure. Many protein structures incorporate metal ions, exploiting their unique
chemistry as reaction centres or for structural stability. This thesis describes the
progress made towards solving the structures of three such metal-binding proteins by
means of X-ray crystallography.

Complement component C1 is a large protein complex that initiates the first
line of immune defence and requires calcium for structural stability. Fragments of C1
have already been solved at high resolution, but there are no accurate models of the
assembled complex. In this work, a new method for purifying intact C1 from human
serum was developed and the purified complex was characterised by various methods.
Finally, attempts were made to crystallise native human C1 with a view to obtaining
high-resolution structures of the entire complex.

Serum amyloid P is another serum protein, also thought to be involved in the
immune response. It is often found associated with amyloid deposits, although SAP
binds a variety of ligands in a calcium-dependent manner. While the structure of SAP
has been determined, its physiological function is still not fully understood. SAP was
purified using established methods and its ligand-binding properties were investigated
under various conditions using dynamic light scattering, in an attempt to gather more
information about the possible function of this molecule.

Finally, ZiCo is a small peptide that was designed to switch between a
multimeric coiled coil and a monomeric zinc finger fold on binding zinc. The system has
been characterised extensively in solution, but high-resolution structures are required to
validate the design. ZiCo was crystallised and diffraction data were collected. The
structure of the peptide was partially solved, indicating that the multimeric form of the
ZiCo peptide is indeed a trimeric coiled coil.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Life Sciences > Biochemistry
Subjects: Q Science > QD Chemistry > QD0241 Organic chemistry > QD0415 Biochemistry
Depositing User: Library Cataloguing
Date Deposited: 29 Sep 2011 09:15
Last Modified: 21 Aug 2015 12:09
URI: http://srodev.sussex.ac.uk/id/eprint/7414

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