| meso-cystine | An isomer of cystine in which the configuration about one of the alpha-carbons is d, about the other, l, so that the molecule as a whole possesses a plane of symmetry and is optically inactive. Note that meso-cystine is not dl-cystine. Dl-cystine is a racaemic mixture of dd-cystine and ll-cystine. (05 Mar 2000) |
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| half cystine | Refers to one-half of a cystine molecule or of a cystinyl residue in a protein or peptide. (05 Mar 2000) |
| cystine | <amino acid> The amino acid formed by linking two cysteine residues with a disulphide linkage between the two SH groups. The analagous compound present within proteins is termed two half cysteines. (18 Nov 1997) |
| cystine bridge | A disulfide linkage between two cysteinyl residues in a poly-or oligopeptide or in a protein, any disulfide linkage between any thiol-containing moieties of a larger molecule. Synonym: cystine bridge. (05 Mar 2000) |
| cystine calculus | A calculus composed of cystine, soft and faintly radiopaque. (05 Mar 2000) |
| cystine desulfhydrase | <enzyme> A multifunctional pyridoxal phosphate enzyme. In the final step in the biosynthesis of cysteine it catalyses the cleavage of cystathionine to yield cysteine, ammonia, and 2-ketobutyrate. Chemical name: L-Cystathionine cysteine-lyase (deaminating) Registry number: EC 4.4.1.1 (12 Dec 1998) |
| cystine disease | Lysosomal storage disorders of unknown molecular defect, characterised by widespread deposition of cystine crystals in reticuloendothelial cells. (12 Dec 1998) |
| cystine lyase | <enzyme> An enzyme catalyzing the hydrolysis of l-cystathionine to pyruvate, l-homocysteine, and NH3. See: cystathionine gamma-lyase. Synonym: beta-cystathionase, cystine lyase. (05 Mar 2000) |
| cystine storage disease | Lysosomal storage disorders of unknown molecular defect, characterised by widespread deposition of cystine crystals in reticuloendothelial cells. (12 Dec 1998) |
| L-cysteine-cystine C-S lyase | <enzyme> C-des - cysteine desulfhydrase; a pyridoxal phosphate- containing enzyme from synechocystis involved information of fe-s cluster of ferredoxin; catalyses the breakdown of l-cysteine to yield sulfide, pyruvate and ammonia; increased activity with cystine, yielding cysteine persulfide as the primary product; mw about 43 kD Registry number: EC 4.4.1.- Synonym: c-des lyase (26 Jun 1999) |
| chiral crystal | An enantiomorphic, dyssymmetric, optically active crystal. (05 Mar 2000) |
| phase, crystal | <microscopy> A specific crystal structure, usually given a name. (05 Aug 1998) |
| clathrate crystal | Lattice-like arrangement of molecules of one substance surrounding molecules of another substance. (05 Mar 2000) |
| crystal | A solid of regular shape and, for a given compound, characteristic angles, formed when an element or compound solidifies slowly enough, as a result either of freezing from the liquid form or of precipitating out of solution, to allow the individual molecules to take up regular positions with respect to one another. Origin: G. Krystallos, clear ice, crystal (05 Mar 2000) |
| crystal, birefringent | <microscopy> A crystalline substance which is anisotropic with respect to the velocity of light. (05 Aug 1998) |