Detached side-chain structures

Detached side chain structures. It was previously found (75) that detached side chain structures (5-8,14, Figure 1) can be liberated from spruce wood by mild acidic but not by mild alkaline hydrolysis. All detached side-chain structures were isolated as derivatives of pyruvaldehyde enol ethers in a total amount of approximately 6% (based on lH NMR) of the total product mixture from spruce wood. 

H Aimi, Y Matsumoto, G Meshitsuka. Lignin fragments rich in detached side-chain structures found in water-soluble LCC. J Wood Sci 51 252-255, 2005. 

When the same heme is bound to the protein of cytochrome two donor atoms from the protein are bound to the iron atom, a nitrogen from a histidine imidazole and a sulfur from a methionine (Fig. 3). The porphyrin is held very tightly in the protein structure by the addition of two cysteine sulfhydryl groups across the double bonds of the two vinyl side chains of the porphyrin. Since the function of cytochrome c is electron transfer, and not the attachment and detachment of additional ligands, the cytochrome c structure is tailored to produce very stable binding of the porphyrin to the protein. 

After removal of the tert-butyl and trityl side-chain-protecting groups with TFA, galactosylation, sialylation, and fucosylation were successively performed using the corresponding glycosyltransferases and donor substrates. Finally, the advantages of mild and reliable detachment from the solid support by use of the Hycron/Pd(0) system was demonstrated with this complex and sensitive structure (86). 

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