Thiourea linkage

Thiourea Linkages. Attachment of saccharide units to the surface of PAMAM through thiourea linkages offers one of the most efficient ways to develop multivalent ligands quickly and efficiently for the study of protein-carbohydrate interactions. 

SCHEME 52. Manal-2Man disaccharide attached to PAMAM via thiourea linkages. 

The Lipari-Szabo approach was used to understand the cause of the pH-dependent relaxivities of PAMAM-type dendrimeric Gdm complexes (74). Three different generations (5,7,9) of PAMAM dendrimers loaded with the [Gd(EPTPA)(H20)]2 chelate via a benzyl-thiourea linkage have been investigated (Scheme 8). The relaxivities show a strong and reversible pH dependency for all three dendrimer complexes,... 

Scheme 4 Heptameric a-thioaryl sialosides at the convergent rim of / -cyc-lodextrin using thiourea linkages...

The resulting electron shift creates a thiourea linkage between TRITC and the protein with no leaving group. 

Fluorescein isothiocyanate (FITC) is the most common fluorescent label used to modify proteins and other biomolecules (Chapter 8, section 1.1). The isothiocyanate group reacts with amines in protein molecules to form a stable thiourea linkage (Fig. 365). Avidin or streptavidin may be tagged with this reagent to yield highly fluorescent... 

Formation of thiourea linkages from isothiocyanates and e-amino groups of lysine residues in proteins... 

SCHEME 19.6 Modification of the Lys side chain to form urea or thiourea linkages. 

The aromatic protons bonded to the nitrogen nuclei of the thiourea group are neither strongly shielded nor deshielded. They appear in the spectrum as a complex band in the chemical shift range from about 6.9 to 7.7 ppm. The shape and complexity of this higher order pattern is quite sensitive to the presence and type of other substituents bonded to the thiourea linkage. 

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