Class Notes (808,126)
Canada (493,084)
Chemistry (602)
CHEM564 (32)
Lecture 1

CHEM564 Lecture 1: Case study.1

4 Pages
Unlock Document

University of Alberta
Christopher Cairo

BioconjugateChemistry Cairo 6 Applications of bioconjugate strategies 6.1 Case Studies in bioconjugate chemistry 6.1.1 Surface immobilization of proteins Protein immobilization chemistry generally takes advantage of amine or carboxylate functional groups on proteins. A problem with this approach in solution is that the proteins themselves have multiple copies of each functional group (except in rare instances). Thus, in solution, addition of a coupling agent (such as EDCI) will result in a complex mixture of crosslinked proteins unless carefully controlled (Scheme I). By moving one of the components to a surface, we can easily control the relative concentrations of the functional groups, and prevent undesired interactions. An excellent illustration of protein crosslinking chemistry can be found in the use of surface plasmon resonance (SPR). SPR can be used to detect the binding of biomolecules to a surface in real time, and therefore provides a window to thermodynamic and kinetic features of these interactions. The simplest form of an SPR experiment would be to immobilize an antibody to the surface, and detect the binding of a protein antigen. We first need a way to immobilize the antibody of interest. As alluded to above, we can take advantage of the functional groups inherent to the antibody structure (amines and carboxylates). On the other side of the problem, we need a compatible functional group on the surface. The surface must contain a gold film (to allow 217 BioconjugateChemistry Cairo detection by SPR), and a variety of chemistries are compatible with the gold surface. One route is to generate a gold-thiol dative bond. This is best illustrated by the formation of self-assembled monolayers (SAM), for example with alkane-thiols. 1,_ENREF_1 These monolayers can be used to introduce specific functional groups, or hydrophobic surfaces for lipid capture. 4 Alternatively, alkanethiols can be used to introduce more versatile functional groups and to improve the properties of the surface. The use of a polymeric substrate provides increased surface density relative to monolayer, and dextran has been a common choice. Oxidation of the dextran to carboxymethyldextran (CMD) provides a hydrophilic polymer,withlowpI,and 5 allows us to take advantage of the carboxylate functional group for crosslinking chemistry. Once an SPR sensor with a CMD surface is in place, we can indirectly observe several chemistries discussed earlier for protein crosslinking. A thorough example is provided by O’Shannessy et al., who demonstrate the application of EDCI/NHS activation for amine, 6 maleimide, and hydrazide coupling (Scheme III). Note that moving the activation chemistry to the surface eliminates any issues of protein crosslinking, as the electrophilic NHS-ester is always restricted. 218 BioconjugateChemistry
More Less

Related notes for CHEM564

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.