Cystine crystal structure

Clausen T, Kaiser JT, Steegborn C, et al. 2000. Crystal structure of the cystine C-S lyase from Synechocystis stalibization of cysteine persulfide for FeS cluster biosynthesis. Proc Natl Acad Sci USA 97 3856-61. 

BMP-2 has in common with BMP-7 and other members of the TGF-P family, a structural scaffold, consisting of a cystine-knot motif and two finger-like double-stranded P-sheets which determine the mode of dimerization. Secondary-structure differences between BMP-2 and BMP-7 account for the recognition and specific interaction with different binding partners. The crystal structure of human bone morphogenetic protein-2 is shown in Fig. 6.2. 

The structures of dimethyl disulfide and bis(trifluoromethyl) disulfide have been determined by electron diffraction, by Stevenson and Beach (211) and by Bowen (35), respectively. Crystal structure determinations of the following disulfides have been carried out di-p-bromophenyl disulfide by Toussaint (216) A M -diglycyl-L-cystine dihydrate by Yakel and Hughes (232) hexagonal L-cystine by Oughton and Harrison (183) L-cystine hydrochloride by Steinrauf et al. (210) and formamidinium disulfide diiodide and dibromidc monohydrates (104). 

The amino acid sequence of decorin includes six cysteine residues paired to form three disulphides (23). The crystal structure of decorin (21) revealed that the four cysteines on the A -terminal side of the LRR domain contained within a CxjCxCx C motif form a cystine knot, with the first cysteine connected to the third and the second to the fourth. The third disulphide located toward the C-terminal end of the LRR domain connects LRRs 11 and 12, providing a stable scaffold anchoring the ends of the flexible ear loop. Collectively, these three disulphides, and the tertiary structure they maintain, are critical for function because chemical reduction (23) leads to irreversible loss of the ability of decorin to bind to collagen (see below). 

Water can plasticize hair by interaction with the core of the cell but loses the water when dried. The outer structure contains cystine that has a disulfide linkage and these crosslinks are important in determining the overall organization of the chains within the hair structure and control the detailed morphology that can be adopted. Differences between hair types are reflected in different distributions of the keratin chains, the nature and distribution of the proteins and the type and distribution of the pigment. The proteins, in this case, are playing an important role in the control of the formation of the crystal structure within the core fibres. 

Jones. D.D. Bernal, L Frey, M.N. Koetzle, T.F. Precision neutron diffraction structure determination of protein and nucleic acid components. XIV. Crystal and molecular structure of the amino acid L-cystine dihydrochloride. Acta Crystallogr., B 1974, 30. 1220-1227. 

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