Site-directed conjugation

Geoghegan, K.E, and Stroh, J.G. (1992) Site-directed conjugation of nonpeptide groups to peptides and proteins via periodate oxidation of a 2-amino alcohol. Applications to modification at N-terminal serine. Bioconjugate Chem. 3, 138-146. 

Geoghegan KF, Stroh JG. Site-directed conjugation of nonpep- 104. 

Geng J, Mantovani G, Tao L, Nicolas J, Chen G, Wallis R, Mitchell DA, Johnson BR, Evans SD, Haddleton DM (2007) Site-directed conjugation of clicked gfycopolymers to form glycoprotein mimics binding to mammalian lectin and induction of immunological function. J Am Chem Soc 129 15156-15163... 

Site directed delivery This approach of conjugating av 33 integrin ligand with a chemotherapeutic agent for optimal efficacy and safety in cancer is under investigation. Earlier work demonstrated the validity of this concept [10]. 

Rogers F.A., Vasquez K.M., Egholm M., Glazer P.M. Site-directed recombination via bifiinctional PNA-DNA conjugates. Proc. Nad. Acad. Sci. USA 2002 99 16695-16700... 

An alternative approach is that adopted by Horrocks and co-workers, where the aromatic residues in metal-binding proteins are used as sensitizers. Since the distance between the metal and the donor is effectively fixed, this provides a rigid scaffold for the experiment, and the absence of a directly conjugated pathway between the metals means that Forster (through space) energy transfer can be assumed. The r-6 distance-dependence of this means that the extent of sensitized emission from the lanthanide ion provides information on the spatial relationship between the metal-ion binding site (lanthanide ions often bind at Ca2+ sites) and nearby aromatic residues. 58-60... 

In some cases, mild reducing conditions can free one or more —SH groups for conjugation or modification purposes. The creation of free sulfhydryls in this manner allows for site-directed modification at a limited number of locations within the protein molecule. 

Other non-protein molecules, such as nucleic acids and oligonucleotides, may not normally possess primary amines of sufficient nucleophilicity to react with common modification reagents. The ability to add amine functionalities to these molecules is sometimes the only route to successful conjugation. Creating amines at specific sites within these molecules allows for site-directed modification at known positions, thus better assuring active conjugates once formed. 

If the substituent is attached to an sp2-hybridized carbon atom that is not directly conjugated with the reaction site, then it is correlated with the Hammett equation using the am constants. 

The conjugation of deacetylvinblastine to a monoclonal antibody that recognizes a tumor-associated antigen results in an agent with substantial antitumor activity in mice with relatively little toxicity (la). Conjugates of this type are of obvious interest for future clinical trials as site-directed cancer chemotherapeutic agents. 

Besides being presently the most efficient method for site-directed interchain disulfide bridging of two different cysteine peptides, this procedure is also recommended for a controlled peptide-protein conjugation by reacting Npys-protected cysteine peptides with properly thiol-functionalized protein carriers. 1761 In this conjugation procedure the amount of peptide grafted to the protein is quantitatively determined by measuring spectro-photometrically at 430 nm the amount of 3-nitropyridine-2(l//)-thione liberated in the reaction. An example of this approach is outlined in Scheme 18. 

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