Carbodiimide modification

Carbodiimide modification of the phosphomonoester end groups on DNA molecules was first used in Khorana s lab to determine nucleotide sequences (Ralph et al., 1962). That early... 

Water soluble carbodiimides inhibit the transcription of supercoiled PM2 DNA with E. coli B RNA polymerase. " Modification of the lactose permease of E. Coli with carbodiimides shows a preference for hydrophobic carbodiimides (DCC) over hydrophilic carbodiimides. In carbodiimide modification of EmrE, a small multidrug transporter in E. Coli, DIPCD modification indicates that Glu-14 is the target of the reaction. Polynucleotides react with positively charged water soluble carbodiimides much faster than do the monomers, owing to their electrostatic effect. ... 

The role of carboxylic groups of the synthetic copolymer is significant. The postulated mechanism of carbodiimide modification of this group appears to be substantiated in the present studies. 

Modification of cellular polymers by incorporating amide, imide, oxa2ohdinone, or carbodiimide groups has been attempted but only the urethane-modified isocyanurate foams are produced in the 1990s. PUIR foams often do not require added fire retardants to meet most regulatory requirements (34). A typical PUIR foam formulation is shown in Table 6. 

Carbodiimides have been prepared by desulfurization of thioureas by metal oxides, by sodium hypochlorite,4 or by ethyl chloroformate in the presence of a tertiary amine by halogena-tion of ureas or thioureas followed by dehydrohalogenation of the N,N -disubstituted carbamic chloride 8 and by dehydration of disubstituted ureas using -toluenesulfonyl chloride and pyridine.7 The method described above is a modification of that of Campbell and Verbanc. ... 

Modification of the ATPase by ATP-EDC occurred without significant incorporation of the nucleotide into the enzyme, suggesting that the inhibition of enzymatic activity is entirely due to intramolecular crosslinking by the carbodiimide moiety... 

Let us return to the hexanucleotide synthesis described above the yields of new matrix were not as high as had been hoped. There are various reasons for this for example, the condensation agent was inactivated by hydrolysis, and higher amounts of carbodiimide had to be used. In order to obtain higher yields of C, it was necessary to modify the building block B (for example by an amino modification). These changes led to an increase of the reaction rate by a factor of 104. 

Figure 1.88 The maleimide group of BMPA reacts with a thiol-containing molecule to result in a modification having a terminal carboxylate group. Amine-containing molecules then can be conjugated to the carboxylate using a carbodiimide reaction with EDC.

Dextran derivatives containing carboxyl- or amine-terminal spacer arms may be prepared by a number of techniques. These derivatives are useful for coupling amine- or carboxylate-containing molecules through a carbodiimide-mediated reaction to form an amide bond (Chapter 3, Section 1). Amine-terminal spacers also can be used to create secondary reactive groups by modification with a heterobifunctional crosslinking agent (Chapter 5). 

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