Cross-linked protein complexes

Guerrero C, Tagwerker C, Kaiser P, et al. An integrated mass spectrometry-based proteomic approach quantitative analysis of tandem affinity-purified in vivo cross-linked protein complexes (QTAX) to decipher the 26 S proteasome-interacting network. Mol. Cell. Proteomics. 2006 5 366-378. 

Tannins are one of several antinutritional factors present in dry beans. Any polyphenolic compound that precipitates proteins from an aqueous solution can be regarded as a tannin (11). Tannins precipitate proteins due to functional groups that complex strongly with two or more protein molecules, building up a large cross-linked protein-tannin complex (12). 

Norcum MT, Warrington JA. Structural analysis of the multienzyme aminoacyl-tRNA synthetase complex A three domain model based on reversible chemical cross-linking. Protein Sci 1998 7 79-87. 

In other studies, Intact FqFi complexes were treated with chemical cross-linking agents that covalently linked the y and e subunits and the c-subunlt ring. The observation that such treated complexes could synthesize ATP or use ATP to power proton pumping indicates that the cross-linked proteins normally rotate together. 

For the sake of better reproducibility, you should not polymerize the SDS gel in the presence of SDS. SDS forms micelles, which contain acrylamide monomers. The micelles disrupt the homogeneous polymerization and provide for unpolymerized acrylamide in the gel. Unpolymerized acrylamide can block N-terminals or cross-link proteins. How does the SDS get into the gel later From the running and sample buffer SDS nms faster than the SDS protein complexes. Thus, the latter always move in an SDS-containing environment. 

In a typical bottom-up approach, cross-linked proteins or protein complexes are separated typically by one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and subjected subsequently to enzymatic in-gel digestion, chromatographic fractionation, and mass spectrometric analysis [138]. Ultimately, the assignment of distance constraints, within a single protein or protein... 

The most obvious approach is to digest with a nuclease the cross-linked protein-nucleic acid complex so as to remove regions of the nucleic acid that are not cross-linked to the protein. However, discretion must be exercised in the choice of nuclease. For example, a nonspecific nuclease, such as T2 ribonuclease, is of little value since it may leave only mononucleotide units attached to the protein. Because the four common nucleotides are distributed throughout the nucleic acid, determination of... 

Zinc cross-links proteins in a manner similar to S-S bridges. For example, insulin may be formulated as its zinc complex in order to produce a slow-release form of the dmg. In the body, this cross-linking results in the formation of zinc fingers in receptor proteins which are important binding sites for hormones such as corticosteroids. 

After penetration of the hide by the chromium the pH is raised to about 3.5—4.0. At this higher pH a change occurs in the chromium complexes as the basicity of the chromium increases and binding to the protein becomes possible. Chromium binds firmly to the protein forming a cross-link species, and as the pH increases the hydrogen is removed from the complex forming a stable stmcture. 

Mechanism of Dyeing. Wool (qv) is a complex protein polymer based on amino acid building blocks, and the polymer chains are cross-linked by disulfide groups. Amino acids (qv) contain both amino and carboxyUc acid groups and therefore the wool polymer contains both —NH2... 

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