Activity conjugates

Danishefsky et al. were probably the first to observe that lanthanide complexes can catalyze the cycloaddition reaction of aldehydes with activated dienes [24]. The reaction of benzaldehyde la with activated conjugated dienes such as 2d was found to be catalyzed by Eu(hfc)3 16 giving up to 58% ee (Scheme 4.16). The ee of the cycloaddition products for other substrates was in the range 20-40% with 1 mol% loading of 16. Catalyst 16 has also been used for diastereoselective cycloaddition reactions using chiral 0-menthoxy-activated dienes derived from (-)-menthol, giving up to 84% de [24b,c] it has also been used for the synthesis of optically pure saccharides. 

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. 

Pool the fractions containing antibody and immediately mix with an amount of maleimide-activated enzyme to obtain the desired molar ratio of antibody-to-enzyme in the conjugate. Use of a 4 1 (enzymerantibody) molar ratio in the conjugation reaction usually results in high-activity conjugates suitable for use in many enzyme-linked immunoassay procedures. Higher molar ratios also have been used with success. 

Frequently, the major proteinaceous part of these products is not active conjugate, but leftover enzyme that contributes nothing to the immunochemical activity of what was purchased. 

If an individual nucleotide is modified in the appropriate way, various enzymatic techniques can be used to polymerize the derivative into an existing oligonucleotide molecule. Alternatively, nucleotide polymers can be treated with chemical activators that can facilitate the attachment of a label at particular reactive sites. Thus, there are two main approaches to modifying DNA or RNA molecules enzymatic or chemical. Both procedures can produce highly active conjugates for sensitive assays to quantify or localize the binding of an oligo probe to its complementary strand in a complex mixture. 

Proteins are sometimes classified as simple or conjugated . Simple proteins consist exclusively of polypeptide chain(s) with no additional chemical components present or being required for biological activity. Conjugated proteins, in addition to their polypeptide components(s),... 

Formation of C-C bonds remains the ultimate challenge to the synthetic chemist. The employment of new synthetic methods in complex target synthesis can be frustrated by a lack of functional group tolerance and substrate specificity. These problems can be somewhat alleviated within conjugate addition reactions by the use of secondary amine catalysts where a number of important and highly selective methods have been developed. Two principle classes of nucleophile have been shown to be effective in the iminium ion activated conjugate addition of carbon nucleophiles to a,P-unsaturated carbonyl systems aryl, heteroaromatic and vinyl... 

Animal tissues, absorption and deposition of conjugated dienoic isomers of linoleic acid, 263-268 Anosmias, flavor chemicals, 19,2U Anticarcinogenic activity, conjugated dienoic derivatives of linoleic acid, 268-269... 

Another option for the preparation of allenyllithium reagents involves the carbolithia-tion of activated conjugated enynes15. Thus, addition of BuLi to the enyne 281 led to an allenyllithium compound 282 (in metallotropic equilibrium with its propargylic counterpart). Subsequent addition of allylzinc bromide generated the allylic 1,1-dimetallic species... 

II reaction usually results in high-activity conjugates suitable for use in many... 

Organized to efficiently cover the chemistry of bioconjugation, l the major reagents available for modification and cross-linking, and the application of these reagents to the synthesis of highly active conjugates... 

Conjugation reactions usually involve metabolite activation by some high-energy intermediate and have been classified into two general types type I, in which an activated conjugating agent combines with the substrate to yield the conjugated product, and type II, in which the substrate is activated and then combines with an amino acid... 

Acylation reactions are of two general types, the first involving an activated conjugation agent, coenzyme A (CoA), and the second involving activation of the foreign... 

H. Goto, K. Akagi, Optically Active Conjugated Polymers Prepared from Achiral Monomers by Polycondensation in a Chiral Nematic Solvent, Angetv. Chem. Int. Ed. 2005, 44, 4322-4328. 

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