Intrachain disulfide bonds

Figure 12.5 Proteolytic cleavage of prothrombin by factor Xa, yielding active thrombin. Although prothrombin is a single-chain glycoprotein, thrombin consists of two polypeptides linked by what was originally the prothrombin intrachain disulfide bond. The smaller thrombin polypeptide fragment consists of 49 amino acid residues, and the large polypeptide chain contains 259 amino acids. The N-terminal fragment released from prothrombin contains 274 amino acid residues. Activation of prothrombin by Xa does not occur in free solution, but at the site of vascular damage...

This enzyme (RNase A) is a single chain protein of 124 amino acid residues, cross-linked by four intrachain disulfide bonds. Limited proteolysis of the enzyme cuts a single peptide bond between residues 20 and 21 (Richards and Vithayathil, 1959). The derived protein, RNase S, retains enzymic activity although the N-terminal peptide of 20 amino acids (S-peptide) is no longer covalently attached to the balance of the molecule (S-protein). Removal of S-peptide from... 

When the disulfide connectivity of a short peptide, consisting of about 20 amino acid residues or less with two intrachain disulfide bonds, has to be determined, the task is generally carried by synthesizing the three possible disulfide isomers (globule/ribbon/beads) and subsequent chromatographic comparison with the natural peptides. The isomers are synthesized by the two-step selective disulfide forming methods based on orthogonal cysteine... 

The assembly of polypeptide chains into functional fibrinogen molecules has been studied in several expression systems. The order in which the polypeptide chains are joined together by disulfide bonds has been determined and specific structural features that are important for assembly, such as the coiled-coil, have been identified (Xu et al., 1996). Substitution of the cysteines with serine showed that the interchain disulfide ring at the proximal end of the coiled-coil, in addition to the disulfides between the two halves of the molecule, are necessary for assembly of the two half molecules (Zhang and Redman, 1996). The distal interchain disulfide ring is not necessary for assembly of the two half molecules but is necessary for secretion. Disruption of intrachain disulfide bonds and deletions of portions of the polypeptide chains have revealed which... 

Figure 17. Schematic diagrams of some representative topologically chiral proteins.79 (a) Condensed schematic drawing of the L subunit of the quinoprotein TV-MADH. The looped line represents the polypeptide backbone with N and C terminals. Cysteine (or half-cystine) residues are numbered, and their a-carbons are indicated by filled circles. Intrachain disulfide bonds are shown as dashed lines joining a pair of filled circles. The heavy line symbolizes an intrachain cofactor link, (b) Chromatium high potential iron protein (HiPIP), one of several Fe4S4 cluster-containing proteins, (c) Toxin II from the scorpion Androctonus australis Hector. Reprinted with permission from C. Liang and K. Mislow, J. Math. Chem. 1994,15,245. Copyright 1994, Baltzer Science Publishers.

Leonard CK, Spellman MW, Riddle L, Harris RJ, Thomas JN, Gregory TJ (1990), Assignment of intrachain disulfide bonds and characterization of potential glycosylation sites of the type 1 recombinant human immunodeficiency virus envelope glycoprotein (gpl20) expressed in Chinese hamster ovary cells, J. Biol. Chem. 

Fig. 6. Loop structures in the NCI domain of collagen IV chains. The beginning portion of the triple-helical domain is shown as a jagged line labeled N. The NCI domain contains two repeating structures, each comprising a large loop, followed by a small loop, and then another large loop. The location of the intrachain disulfide bonds has been deduced (Sieboldt el al., unpublished).

Cereal prolamins, named glutenins and gliadins in wheat, secalins in rye, and horde-ins in barley, are major storage proteins of the cereal grain endosperm. These sulfur-rich proteins comprise an N-terminal domain of proline- and glutamin-rich repeats and a C-terminal domain responsible for intrachain disulfide bonds (Breiteneder and Radauer 2004). So far, y-3 hordein (Hor v 21) from barley, Sec c 20 from rye, as well as Tri a 19 and Tri a 26 from wheat are included in the IUIS allergen list. 

Figure 1. Diagram showing the structure of an immunoglobulin molecule. It comprises two identical heavy (H) chains and two identical light (L) chains. Inter-and intrachain disulfide bonds ( ) contribute to the structure and stability of the molecule.

Fig. 1. Comparison of the three-dimensional structures of human Interleukin-8 (green) MCP-1 (blue) and Fractalkine (EST Z44443) (red). The 11-8 structure is taken from the Protein Database (PDB) entry (1IL8), and the MCP-1 structure is a model built of the NMR structure of MI P-l (> (PDB entry 1HUM). The intrachain disulfide bonds are shown in yellow. The model for the chemokine domain of Fractalkine was built using the SwissModel server (16,17). As can be seen the three structures show a large degree of conservation of the overall structure, despite a relatively low level of primary sequence identity. The additional three amino acids in Fractalkine are accommodated as a 310 helix between the two N-terminal cysteines. The steric requirements here presumably forbid a CX2C motif. The model building software can be accessed at http www.expasy.ch swissmod SWISS-MODEL.html...

Recombinant human interleukin-4 (rhIL-4) is a monomeric protein with a molecular weight of 15,400 Da and pi of 9.2, with three intrachain disulfide bonds. It is a cytokine that has been investigated for cancer therapy. CZE of rhIL-4 mixtures prepared by in vitro degradation has been performed in uncoated capillaries with 50 m M 1,3-diaminopropane and phosphate buffers with pH ranging from 4.5 to 8.O.40 The resolution of degradation products by CZE appeared to be superior to HPLC. 

Proteins, due to the complexity of their chemical structures, undergo oxidative modifications in subsequent stages which depend both on the presence of oxidation-susceptible groups and on steric availability of these groups for oxidant attacks (S25). Some oxidative structural modifications produced in proteins are common in various oxidants. Some modifications, such as chlorinated and nitrated protein derivatives produced in reactions with hypochlorite, peroxynitrite, and nitric dioxide, are specific for the oxidants employed. Certain oxidative protein modifications, such as interchain or intrachain disulfide bond formation or thiolation, are reversible and may be reduced back to the protein native form when oxidative stress is over (Dl). Other changes, such as sulfone formation, chlorination, and nitration, are irreversible and effect protein denaturation and promote its subsequent degradation. 

On the basis of these data, the following model of the subunit structure is proposed the snail hemagglutinin consists of 6 identical, polypeptide chains (subunits), each containing one intrachain disulfide bond and a carbohydrate binding-site. Furthermore, two subunits are linked by an intrachain, disulfide bond to form subunit dimers of molecular weight 26,000, and three dimers (mol. wt. 26,000) are held together by noncovalent interactions.569... 

Disulfide (-S-S-) bonds play an important role in the structure and function of proteins. IgG molecules are comprised of two heavy and two light chains linked by interchain disulfide bonds. In addition, intrachain disulfide bonds are also present in IgGs. Alkyl thiols have been used to demonstrate the structural and functional role played by disulfide bonds. Reduction of IgGs with alkyl thiols under denaturing conditions results in separation of light and heavy chains. 

ANP, Atriopeptin) intrachain disulfide bond (28 aa) adrenal tissues blood pressure... 

In 1960, Hirs, Moore, Stein, and Anfinsen described the first primary structure of the enzyme ribonuclease (M.W. 13,700), which has a single peptide chain of 124 amino acid residues and four intrachain disulfide bonds. These investigators established many of the techniques still used in sequence analysis, such as the use of ion exchange resins for separation of peptides and amino acids. 

Notice that insulin consists of two chains (shown in blue and yellow) linked by two interchain disulfide bonds. The a chain (blue) also has an intrachain disulfide bond. [Drawn from IB2F.pdb. 

Figure 14,25 Structure of epidermal growth factor. Notice that three intrachain disulfide bonds stabilize the compact three-diiTiensional structure of the growth factor, [Drawn from lEGF.pdb,]...

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