| cross-linking reagent | <chemistry> Reagents with two reactive groups, usually at opposite ends of the molecule, that are capable of reacting with and thereby forming bridges between side chains of amino acids in proteins; the locations of naturally reactive areas within proteins can thereby be identified; may also be used for other macromolecules, like glycoproteins, nucleic acids, or other. (12 Dec 1998) |
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| Hahn's oxine reagent | An alcoholic solution of 8-hydroxyquinoline used in the determination of zinc, aluminum, magnesium, etc. (05 Mar 2000) |
| Hammarsten's reagent | A mixture of 1 part 25% solution of nitric acid and 19 parts 25% solution of hydrochloric acid; the addition of a few drops to a mixture of 1 part of this reagent and 4 parts alcohol will give a green colour if bile is present. (05 Mar 2000) |
| Sanger's reagent | A reagent used to combine with the free NH2 group of the NH2-terminal amino acid residue in a peptide, thus marking this residue; the combined forms are known as DNP-proteins, Dnp-aminoacyl, etc., the fluorine having been replaced to leave a dinitrophenyl residue (DNP, Dnp, or N2Ph-) attached to the NH2 group. Synonym: Sanger's reagent. Acronym: FDNB (05 Mar 2000) |
| Schaer's reagent | An alcoholic or aqueous solution of chloral hydrate used as an extraction medium in investigations of alkaloids. (05 Mar 2000) |
| Scheibler's reagent | A solution of sodium tungstate in phosphoric acid used in tests for alkaloids. (05 Mar 2000) |
| Schiff's reagent | An aqueous solution of basic fuchsin or pararosaniline which is decolorised by sulfur dioxide, commonly prepared by addition of hydrochloric acid to a dye solution containing a metabisulphite or bisulphite salt; used for aldehydes and in histochemistry to detect polysaccharides, DNA, and proteins. See: Feulgen stain, periodic acid-Schiff stain, ninhydrin-Schiff stain for proteins. (05 Mar 2000) |
| Scott-Wilson reagent | An alkaline solution of mercuric cyanide and silver nitrate used in the detection of acetone. (05 Mar 2000) |
| Nessler's reagent | A solution of potassium hydroxide, mercuric iodide, and potassium iodide; it yields a yellow colour with ammonia (a brown precipitate with larger amounts) that can be used for quantitative assay. (05 Mar 2000) |
| sulfhydryl reagent | Reagents that react with thiol groups, particularly those in proteins. (05 Mar 2000) |
| Sulkowitch's reagent | A reagent for the detection of calcium in the urine, consisting of 2.5 g of oxalic acid, 2.5 g of ammonium oxalate, 5 cc of glacial acetic acid, and distilled water to make 150 cc; a milky precipitate of calcium oxalate is formed when the reagent is added to urine that contains calcium. (05 Mar 2000) |
| sulphydryl reagent | <chemical, pharmacology> Compounds that bind to SH groups. Include p chlormercuribenzoate, N ethyl maleimide, iodoacetamide. Very important in studies of protein structure. (18 Nov 1997) |
| diazo reagent | Two solutions, one of sodium nitrite, the other of acidified sulfanilic acid, used in bringing about diazotization. Synonym: Ehrlich's diazo reagent. (05 Mar 2000) |
| Dische reagent | The assay of DNA by means of the blue colour formed with diphenylamine in acid (Dische reagent). (05 Mar 2000) |
| Dische-Schwarz reagent | Reagent used in the colourimetric detection of RNA. (05 Mar 2000) |