Bonding disulphide

Mongar JL, Rosenoer VM. The preparation of urogastrone. J Physiol Lond 162 163-172, 1962 Rosenoer VM. The relation of peptide bonds, disulphide bonds and sul-phydryl groups to urogastrone activity. J Physiol Lond 162 173-182, 1962. 

Martin, J.E., Bardwell, J.C.A., Kuriyan, J. Crystal structure of the DsbA protein required for disulphide bond formation in vivo. Nature 365 464-468, 1993. 

A number of solvents such as the hydrocarbons, carbon disulphide and carbon tetrachloride are quite incapable of forming hydrogen bonds. 

The selective oxidation of the sulphide grouping in the presence of the disulphide bond was observed when a methanolic solution of amide 46 was treated with an aqueous solution of sodium metaperiodate77 (equation 20). 

Levitt (1962) has of course proposed a theory of frost injury based on the oxidation of sulphydryl groups and the formation of intermolecular disulphide bonds and he has subsequently extended this concept to dehydration injury (see Levitt, 1972). Although popular in the 1960s and 1970s this theory appears to have lost favour in recent years. 

The spore coats make up a major portion of the spore, consisting mainly of protein with smaller amounts of complex carbohydrates and Bpid and possibly large amounts of phosphorus. The outer spore coat contains the alkali-resistant protein fraction and is associated with the presence of disulphide-rich bonds. The alkali-soluble fraction is... 

IgG consists of four polypeptide subunits held together by disulphide bonds. Native immunoglobulins are rather resistant to proteolytic digestion but certain enzymes have been usefiil in elucidating their structure. Papain cleaves the molecule into three fragments of similar size ... 

Intrastrand bonding via disulphide links cause the molecule to fold into globular domains and it is these that direct the biological activity of the molecule. 

Figure 3.4 Transmembrane topology of a 7-TM domain G-protein receptor such as the P-adrenoceptor. Agonist binding is predicted to be within the transmembrane domains. The extracellular structure is stabilised by the disulphide bond joining the first and second extracellular loop. The third intracellular loop is the main site of G-protein interaction while the third intracellular loop and carboxy tail are targets for phosphorylation by kinases responsible for initiating receptor desensitisation...

The fast interaction of O2 with Fe(II)-cysteine complexes to give an oxygen adduct which rapidly undergoes one-electron breakdown to an Fe(III)-cysteine complex and -OJ has been examined by stopped-flow spectrophotometry at 570 nm . Subsequent decomposition of the Fe(IlI) complex to yield Fe(II) and the disulphide, cystine, was much slower. Both mono- and bis-complexes of Fe(Il) are involved and the reaction is first-order in both Fe(II) complex and O2 k (mono) = (5 +1) x 10 l.mole ksec" and k (bis) = (2 0.5) x lO l.mole . sec at 25 °C, corresponding to factors of 10 and 10 times faster than the analogous reactions with sulphosalicylic acid complexes of Fe(II), a feature attributed to Fe(ll)-S bonding in the cysteine complexes. ... 

The crystal structures of a number of diphosphine disulphides (121) and (122) show a remarkable constancy in the bond lengths. Two types of molecule are observed in the crystal of the tetramethyl compound (121, X = Y = Me). The crystal structure of triphenylphosphine oxide (P—C 176 pm, P—O 164 pm) varies little from that observed in the uranium oxide complexes, and does not confirm P—O bond lengthening in complexes, as indicated by vp=.o (see Section 3C). 

Kawamura, M. and Nagano, K. (1984). Evidence for essential disulphide bonds in the beta subunit of the Na/K ATPase. Biochim. Biophys. Acta 774, 188-192. 

Another approach was developed by Scott in the 1970 s (7.8) which utilises the same mechanochemistry used previously by Watson to initiate the Kharacsh-type addition of substituted alkyl mercaptans and disulphides to olefinic double bonds in unsaturated polymers. More recently, this approach was used to react a variety of additives (both antioxidants and modifiers) other than sulphur-containing compounds with saturated hydrocarbon polymers in the melt. In this method, mechanochemically formed alkyl radicals during the processing operation are utilised to produce polymer-bound functions which can either improve the additive performance and/or modify polymer properties (Al-Malaika, S., Quinn, N., and Scott, 6 Al-Malaika, S., Ibrahim, A., and Scott, 6., Aston University, Birmingham, unpublished work). This has provided a potential solution to the problem of loss of antioxidants by volatilisation or extraction since such antioxidants can only be removed by breaking chemical bonds. It can also provide substantial improvement to polymer properties, for example, in composites, under aggresive environments. 

Oxidative bleaching of wool is invariably carried out with hydrogen peroxide. The active species involved is likely to be the same as on cellulosic substrates but specific reactions with wool amino acid residues must be considered. The primary reaction is oxidation of cystine disulphide bonds leading to the formation of cysteic acid residues (Scheme 10.41). The rupture of disulphide crosslinks, with attendant increase in urea-bisulphite and alkali solubility values, adversely affects fibre properties. As the severity of bleaching conditions increases, the urea-bisulphite solubility remains little changed but the relationships between alkali solubility and cysteic acid (Figure 10.36) and between cystine and cysteic acid (Figure... 

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