Cross-linkages in proteins

Cross Linkages in Protein Chemistry Johan Bjorksten... 

Lipoxygenase-Catalyzed Cross-Linkages in Proteins. In order to produce the right texture in bread and similar products, chemicals such as bromates, acetone peroxides, ascorbic acid, azodicarbonamide, calcium... 

The cystine residues, because they may act as cross-linkages between protein chains, have been studied more closely than other residues in keratin. Burley s (1956a) use of the concept of thiol-disulfide interchange to explain the effects of chemical modification on the physical properties of wool fibers has stimulated further work on cysteine and cystine residues. 

Factor XIII will slowly form c-N- (y-glutamyl) lysine cross-linkages in fibrinogen, in itself and in other proteins (37). Transaminases from other sources will also cross-link fibrin, as well as other proteins. In addition, they will covalently attach amino-containing substrates to the y-carboxyl group of glutamic acid residues in proteins (38). 

Compounds that can cause cross-linkage of proteins. Reactions of this type apparently also play a role in vivo (diabetes). 

CP-MAS has allowed the study of conformations and cross-linkages in natural and synthetic polymers, and of structures of proteins, nucleic acids, phospholipid membranes, etc. The field is still in its infancy and its applications will undoubtedly grow. The CP-MAS solid state C-NMR spectrum of 19S-vindolinine, has been studied by Atta-ur-Rahman and coworkers at H.E.J. Research Institute of Chemistry, and it is shown in Figure 4.16. It represents the first example of a CP-MAS spectrum of a solid Aspidosperma alkaloid ever recorded. 

In general, the mechanism of heat and alkaline solution for DNA extraction may be based upon a hypothesis, previously proposed for the AR technique.32 Strong alkaline solution may denature and hydrolyze proteins, resulting in breaking cell and nuclear membranes as well as disrupting cross-linkages due to formalin fixation. It is no surprise to observe the similarity between retrieval of nucleic acid and retrieval of protein (antigen) based on a similar chemical reaction of formaldehyde with these two kinds of macromolecules (Fig. 3.1).15"19... 

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