Latest News on Disulphide Research: Feb – 2020

Disulphide bridges in globular proteins

Disulphide bridges in proteins of known sequence, connectivity and structure were studied to look for common features. Their distribution, topology, conformation and conservation were analysed intimately . Several general patterns emerge which to some extent dictate disulphide bridge formation. for instance , there’s a robust preference for shorter connections, with half-cystines separated by but 24 residues in 49% of all disulphides. Right- and left-handed disulphides occur equally; the left-handed structures adopt one predominant conformation (symmetric χ1 = −60 °, χ2 = −80 °, χ3 = t-90 °). Cystines are generally alright conserved, in contrast to cysteines, with a free —SH group, which mutate rapidly. If a disulphide isn’t conserved, both cystines are mutated. The role of disulphide bridges in globular proteins is discussed. [1]

Disulphide Bonds in Wheat Gluten Proteins

Disulphide bonds play a key role in determining the structure and properties of gluten proteins. Comparison of the sequences of monomeric gliadins and polymeric glutenin subunits allows the identification of conserved and variant cysteine residues. Direct disulphide bond determination demonstrates that the conserved cysteine residues present in S-rich prolamins (α-type gliadins, γ-type gliadins and LMW subunits) form intra-chain disulphide bonds while additional cysteines residues present only within the LMW subunits form inter-chain bonds with cysteines in HMW subunits and other LMW subunits. Conserved and variant cysteine residues also are present within the HMW subunits but their patterns of disulphide bond formation are less well understood. [2]

Disulphide bonds and protein stability

The properties of disulphide bonds relevant to their roles in stabilizing protein conformation are reviewed. Natural disulphides can stabilize folded conformations substantially, in some cases to much greater extents than would be expected from just entropic effects on the unfolded state. The linkage relationship between conformational stability and disulphide stability is illustrated. Disulphides won’t , however, increase protein stability if the disulphides aren’t maintained within the unfolded state or if instability is caused by processes, like chemical modification or proteolysis, that aren’t linked to unfolding, either local or global. this is often a part of the rationale why some recent attempts to extend protein stability by introducing new disulphides have had only modest success. Other reasons appear to be the severe energetic constraints on disulphide bond geometry and, in some cases, unfavourable effects of introducing Cys residues by mutation. [3]

Structural and functional role of disulphide bonds and substrate binding residues of the human beta-galactoside alpha-2,3-sialyltransferase 1 (hST3Gal1)

Overexpression of hST3Gal1 results in hypersialylation of cell-surface glycoconjugates, a cancer-associated condition that promotes cell growth, migration and invasion. Upregulation of this enzyme in ovarian cancer is linked to cancer progression and metastasis, contributing also to chemotherapy resistance. Strategies for preventing metastasis include the inhibition of hST3Gal1, which demands structure-based studies on its strict regioselectivity and substrate/donor preference. Herein we describe the contribution of varied residues constituting donor CMP-Neu5Ac and acceptor Galβ1-3GalNAc-R binding sites to catalysis. Removal of hydrogen bonds and/or stacking interactions among substrates and residues Y191, Y230, N147, S148 and N170 affected the enzyme’s activity to a special extent, revealing the fine control needed for an optimal catalytic performance. [4]

Adsorption Energies of Lithium and Sodium Ions on Vanadium Disulphide: A DFT Study

Various energy sources are utilized at the present with a challenge of energy storage in many cases. the prevailing rechargeable storage batteries which include sodium-ion and lithium-ion batteries have some limitations in their gravimetric capacities. initially methods supported density functional theory (DFT) was wont to investigate the adsorption of lithium ions and sodium ions on layered Vanadium disulphide. Metallic VS2 monolayer features a higher theoretical gravimetric capacity of 466mAh/g. This study showed that Sodium adsorbs on monolayer VS2 with lower adsorption energy of -2.00eV compared to Lithium (1.47eV) and it’s more stable. [5]

Reference

[1] Thornton, J.M., 1981. Disulphide bridges in globular proteins. Journal of molecular biology, (Web Link)

[2] Shewry, P.R. and Tatham, A.S., 1997. Disulphide bonds in wheat gluten proteins. Journal of Cereal Science, (Web Link)

[3] Creighton, T.E., 1988. Disulphide bonds and protein stability. BioEssays, (Web Link)

[4] Structural and functional role of disulphide bonds and substrate binding residues of the human beta-galactoside alpha-2,3-sialyltransferase 1 (hST3Gal1)
Maria Elena Ortiz-Soto, Sabine Reising, Andreas Schlosser & Jürgen Seibel
Scientific Reports, (Web Link)

[5] Murila, G. I., Manyali, G. S. and Wafula, H. B. (2018) “Adsorption Energies of Lithium and Sodium Ions on Vanadium Disulphide: A DFT Study”, Journal of Materials Science Research and Reviews, (Web Link)

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