Covalent conjugation

Stults, N. L., Rivera, H. N., Burke-Payne, J., and Smith, D. F. (1997). Preparation of stable covalent conjugates of recombinant aequorin with proteins and nucleic acids. In Hastings, J. W., et al. (eds.), Biolumin. Chemilumin., Proc. Int. Symp., 9th, 1996, pp. 423-426. Wiley, Chichester, UK. 

Small tfbiquitin-like modifier represents a family of evolutionary conserved proteins that are distantly related in amino-acid sequence to ubiquitin, but share the same structural folding with ubiquitin proteins. SUMO proteins are covalently conjugated to protein substrates by an isopeptide bond through their carboxyl termini. SUMO addition to lysine residues of target proteins, termed SUMOylation, mediates post-transla-tional modification and requires a set of enzymes that are distinct from those that act on ubiquitin. SUMOylation regulates the activity of a variety of tar get proteins including transcription factors. 

Lee et al. reported a novel and simple method for delivery of adriamycin using self-aggregates of deoxycholic acid modified chitosan. Deoxycholic acid was covalently conjugated to chitosan via a carbodiimide-mediated reaction generating self-aggregated chitosan nanoparticles. Adriamycin was... 

Streptavidin-single-stranded DNA covalent conjugates were described as the building blocks for assembling nanostructured scaffolds [31], The amount and type of biotinylated ligands were used to modulate the affinity of duplex formation between solid-phase-bound nucleic acid templates and DNA-streptavidin conjugates. This system has been proposed for the design of fine-tuned sequence detection systems. 

This method represents one of the first attempts towards macromolecular agents.121-123 As many as 60-90 [Gd(DTPA)]2- or [Gd(DOTA)] chelates were first linked to a polylysine chain, then covalently conjugated to a HSA molecule.124 The increase in relaxivity per Gd, as compared with the monomeric chelate, was remarkable (two- to threefold), though far from optimal. However, the development of these albumin conjugates was abandoned at an early stage, since their synthesis is not easily controlled, and there are also toxicity concerns due to the retention of gadolinium observed in the bones and liver.125... 

Cholinesterase catalysis and inhibition mechanisms involve formation of reversible complexes and covalent conjugates 197... 

Raasi, S., Sghmidtke, G., and Groettrup, M., The ubiquitin-like protein EATIO forms covalent conjugates and induces apoptosis, /. Biol. Biol, 2001, 276, 35334. 

PEG-Intron PEG-Intron is used for the treatment of hepatitis C. The product consists of a covalent conjugate of the recombinant interferon- -2b with monomethoxy polyethylene glycol (PEG) supplied in vials with 74/rg, 118.4/rg, 177.6/rg, or 222/rg of the active ingredient and 1.11 mg sodium phosphate (dibasic,anhydrous),l.ll mg sodium phosphate (monobasic, dihydrate), 59.2 mg sucrose, and 0.074mg polysorbate 80. The powder is reconstituted with sterile water-for-injection. 

The X-ray structure of 33F12 revealed that the catalytic mechanisms of this antibody is significantly dependent on LysH93, which initiates catalysis hy forming a stable covalent conjugated enamine with the ketone substrate that becomes the aldol donor. 

Bradley MO, Webb NL, Anthony FH, Devanesan P, Witman PA, Hemamalini S, Chander MC, Baker SD, He L, Horwitz SB, Swindell CS. (2001) Tumor targeting by covalent conjugation of a natural fatty acid to paclitaxel. Clin Cancer Res 7 3229-3238. 

Oh S, Kim BJ, Singh NP, Lai H, Sasaki T. (2009) Synthesis and anti-cancer activity of covalent conjugates of artemisinin and a transferring-receptor targeting peptide. Cancer Lett 274 33-39. 

By using recombinant DNA techniques, modifications in the protein backbone, such as additions, deletions and alterations of amino acids, are easily achieved. These modifications can contribute to improved pharmacokinetic properties of the construct. Additions may consist of the introduction of residues that allow covalent conjugation of drug molecules. Deletions of amino acids can employed to remove membrane-bound regions of a protein, thereby increasing its solubility. Single amino acid modifications can be used to minimize antibody responses and alter the binding specificity and/or the three-dimensional structure of a certain protein. 

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