Poster abstracts
Poster number 25 submitted by Mike Ryan-Simkins
Rational exploration of the biophysical properties of scFV antibody fragments in relation to linker length
Mike Ryan-Simkins (OSBP), Nick Long (OSBP), Mina Hann (Chemistry)
Abstract:
Antibodies are a very important class of biological drugs due in large to their ability to bind a wide array of targets with high specificity. Generally, they have very long serum half-lives and it can take weeks for them to be cleared from a patient’s blood, making them ideal for extracellular targets in cancer and other disease. The minimal binding fragment of antibodies is called the single-chain variable fragment (scFV) which contains a long non-native peptide linker between the two binding domains. Due to their smaller size, scFV antibodies have faster blood clearance giving them great potential for use as specific targeting molecules for use as an imaging agent of cancers and other disease. One way to optimize the functionality of scF¬Vs is optimize the non-native linker that connects the two domains as changes to the linker have been shown to effect biophysical properties such as binding affinity, stability, and oligomeric state. Previous studies have mostly focused on how the length effects the linker properties, but composition effects remain largely unknown. Understanding the role and properties of rigid scFV linkers will greatly improve their potential utility as imaging and therapeutic agents as both stability and sample homogeneity are highly prized attributes. Here we use an scFV called 3E8.scFV which is specific to a tumor marker found in adenocarcinoma cancers as our model scaffold. We have constructed a rational library of poly-proline and poly-alanine linkers to investigate how the linker length effects the biophysical properties of 3E8.scFV when the linker composition is more rigid. We have characterized our comprehensive library with a number of biophysical methods. Our work suggests that short rigid linkers hold a potential advantage in stability and oligomeric state distribution over their more flexible counterparts. Beyond scFVs, we believe our work may be also be important in other genetic fusions where the orientation of the connected domains is important.
Keywords: Antibody Engineering, Oligomeric State