Protein disulfides

Freedman, R.B. The formation of protein disulfide bonds. Curr. Opin. Struct. Biol. 5 85-91, 1995. 

Disulfide bonds between and within polypeptides stabilize tertiary and quaternary structure. However, disulfide bond formation is nonspecific. Under oxidizing conditions, a given cysteine can form a disulfide bond with the —SH of any accessible cysteinyl residue. By catalyzing disulfide exchange, the rupture of an S— bond and its reformation with a different partner cysteine, protein disulfide isomerase facilitates the formation of disulfide bonds that stabilize their native conformation. 

Proteins that assist folding include protein disulfide isomerase, protine- V,rn2 j,-isomerase, and the chaperones that participate in the folding of over half of mammalian proteins. Chaperones shield newly synthesized polypeptides from solvent and provide an environment for elements of secondary stmcture to emerge and coalesce into molten globules. 

Witkiewicz, P.L. and Shaw, C.F. Ill (1981) Oxidative cleavage of peptide and protein disulfide bonds by gold(III) amechanism for gold toxicity. Journal of the Chemical Society, Chemical Communications, (21), 1111-1114. 

Ou W, Silver J. Role of protein disulfide isomerase and other thiol-reactive proteins in HIV-1 envelope protein-mediated fusion. Virology 2006 350(2) 406-417. 

Epe, C., Kohlmetz, C. and Schnieder, T. (1998) A recombinant protein disulfide isomerase homologue from Ancylostoma caninum. Parasitology Research 84, 763-766. 

Kivirikko, K.I. and Pihlajaniemi, T. (1998) Collagen hydroxylases and the protein disulfide isomerase subunit of prolyl 4-hydroxylases. Advances inEnzymology and Related Areas of Molecular Biology 72, 325-400. 

Schonbranner, E.R. and Schmid, F.X. (1992) Peptidyl-prolyl cis-trans isomerase improves the efficiency of protein disulfide isomerase as a catalyst of protein folding. Proceedings of the National Academy of Sciences USA 89, 4510-4513. 

Veijola, J., Koivunen, P., Annunen, P., Pihlajaniemi, T. and Kivirikko, K. (1994) Cloning, baculovirus expression, and characterization of the alpha-subunit of prolyl 4-hydroxylase from the nematode Caenorhabditis elegans - this alpha-subunit forms an active alpha-beta dimer with the human protein disulfide-isomerase beta-subunit. Journal of Biological Chemistry 269, 26746-26753. 

Vuori, K., Pihlajaniemi, T., Myllyla, R. and Kivirikko, K.I. (1992) Site-directed mutagenesis of human protein disulfide isomerase - effect on the assembly, activity and endoplasmic-reticulum retention of human prolyl 4-hydroxylase in Spodoptera frugiperda insect cells. EMBO JoumalW, 4213-4217. 

Wilson, R., Lees, J.F. and Bulleid, N.J. (1998) Protein disulfide isomerase acts as a molecular chaperone during the assembly of procollagen. Journal of Biological Chemistry 273, 9637-9643. 

Wilson, W.R., Tuan, R.S., Shepley, K.J., Freedman, D.O., Greene, B.M., Awadzi, K. and Unnasch, T.R. (1994) The Onchocerca volvulus homologue of the multifunctional polypeptide protein disulfide isomerase. Molecular and Biochemical Parasitology 68, 103-117. 

MTP is responsible for the transfer of TGs and cholesteryl esters from the endoplasmic reticulum (ER) to lipoprotein particles (VLDL in hepatocytes in the liver and chylomicrons in endocytes in the intestine) for secretion [52]. It is a heterodimer consisting of a unique large subunit essential for lipid transfer encoded by the mttp gene and a smaller subunit, the ubiquitous ER enzyme protein disulfide isomerase [53]. 

Protocol for Partial Reduction of Protein Disulfides or for Cleaving Disulfide Containing Modification Reagents... 

Cleland (1964) showed that DTT and DTE are superior reagents in reducing disulfide bonds in proteins (see previous discussion, this section). DTT and DTE have low oxidation-reduction potential and are capable of reducing protein disulfides at concentrations far below that required with 2-mercaptoethanol. However, even these reagents have to be used in approximately 20-fold molar excess in order to get close to 100 percent reduction of a protein. 

Fluorescein-5-maleimide also has been used to study the assembly dynamics of mycobacterium tuberculosis (Chen et al., 2007), to study monomers and dimers of nhaa Na+/H+ antiporter of E. coli (Rimon et al., 2007), and to investigate the regulation of the protein disulfide proteome by mitochondria (Yang et al., 2007). 

Iodoacetate derivatives have been used for decades to block or crosslink sulfhydryl groups in proteins and other molecules (Chapter 1, Section 5.2). At mildly alkaline pH values (pH 8-8.5), iodoacetyl derivatives are almost entirely selective toward the cysteine —SH groups in proteins. Disulfide reduction or thiolation reagents can be used to create the required sulfhydryl groups on proteins containing no free sulfhydryls. 

Reduce protein disulfides by adding dithiothreitol (DTT) to a final concentration of 5mM and incubate for 30 minutes at 60°C. Add iodoacetamide to a final concentration of 25 mM to alkylate the thiols. React for 1 hour in the dark. 

Yi, Y., Song, Y., and Loscalzo, J. (2007) Regulation of the protein disulfide proteome by mitochondria in mammalian cells. PNAS 104, 10813-10817. 

This reaction also protects proteins with cysteine residues from becoming oxidized to the disulfide since the GSH can be used to reduce the protein disulfide back to the thiol form ... 

Mammalian thioredoxin reductases are a family of selenium-containing pyridine nucleotide-disulfide oxidoreductases. These enzymes catalyze NADPH-dependent reduction of the redox protein thioredoxin (Trx), which contains a redox-active disulfide and dithiol group and by itself may function as an efficient cytosolic antioxidant [77]. One of the functions of Trx/ thioredoxin reductase system is the NADPH-catalyzed reduction of protein disulfide [78] ... 

N203-dependent S-nitrosation has been demonstrated in the case of semm albumin (Nedospasov et al, 2000 Rafikova et al., 2002), in membranes (Liu et al., 1998) and in the protein-disulfide isomerase dependent transfer of NO-equivalents from extracellular RSNOs to the cytosol (Ramachandran et al., 2001). 

We and others have demonsttated that an endothelial, cell surface protein-disulfide isomerase-mediated mechanism, does exist for the rapid influx of RSNO bound-NO (Zai et al. 1999 Ramachandran et al., 2001). Whether the csPDI route plays a role in the transfer of NO-equivalents from RBCs remains to be answered. 

Burgess, ). K., FIotchkiss, K. A., Suter, C., Dudman, N. P., Szollosi, J., Chesterman, C. N., Chong, B. H., Hogg, P. J., Physical proximity and functional association of glycoprotein lbalpha and protein-disulfide isomerase on the platelet plasma membrane,/. Biol. Chem. 275 (2000), p.9758-9766... 

Essex, D. W., Chen, K., Swiatkowska, M., Localization of protein disulfide isomerase to the external surface of the platelet plasma membrane, Blood. 86 (1995), p. 2168-2173... 

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