Yellow Derivatives

In addition, DNA and RNA may be modified with hydrazide-reactive probes by reacting their cytosine residues with bisulfite to form reactive sulfone intermediates (Chapter 27, Section 2.1). These derivatives can undergo transamination reactions with hydrazide- or amine-containing probes to yield covalent bonds (Draper and Gold, 1980). 

This fluorophore has an excitation maximum at 400 nm and an emission maximum at 420 nm. The extinction coefficient of the molecule in aqueous solution at pH 7 is about 31,000M 1cm 1. Cascade Blue hydrazide and Lucifer Yellow derivatives can be excited simultaneously by light of less than 400 nm, resulting in two-color detection at 420 and 530nm. 

Cascade Blue hydrazide is soluble in aqueous solution, and it should be stable for awhile if protected from light. A concentrated stock solution of the reagent may be prepared in water and an aliquot added to a buffered reaction medium to facilitate the transfer of small quantities. For aqueous reactions, a pH range of 5-9 will result in efficient hydrazone formation. 

The spectral characteristics of Lucifer Yellow iodoacetamide produce luminescence at somewhat higher wavelengths than the green luminescence of fluorescein, thus the yellow designation in its name. The excitation maximum for the probe occurs at 426 nm and its emission at 530 nm. The rather large Stoke s shift makes sensitive measurements of emission intensity possible without interference by scattered excitation light. The 2-mercaptoethanol derivative of the fluorophore has an extinction coefficient at pH 7 of about 13,000 M cm-1 at 426nm. 

Lucifer Yellow derivatives are used extensively for cytochemical staining applications, especially in neurophysiology (Stewart, 1981a, b). The fluorophores are 3.6-disul- 

Lucifer Yellow probes are water-soluble to at least 1.5%. The absorbance maximum of the derivatives occurs at about 426—428 nm with an emission peak at about 530—535 nm, in the yellow region of the spectrum. The quantum yield of Lucifer dyes is about 0.25. The good intensity of luminosity from these dyes makes possible detection of small quantities of labeled molecules intracellularly. The fluorescent conjugates are readily visible in living cells at concentrations that are nontoxic to cell viability. The low molecular weight and water solubility of these dyes allow passage of labeled compounds from one cell to another, potentially revealing molecular relationships between cells. 

One Lucifer 3fellow derivative is available for labeling sulfhydryl-containing molecules. Lucifer Yellow iodoacetamide is a 4-ethyliodoacetamide derivative of the basic disulfonate aminonaphthalimide fluorophore structure (Molecular Probes). The io-doacetyl groups react with — SH groups in proteins and other molecules to form stable thioether linkages (Fig. 240). 

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Figure 9.43 The hydrazide group of this Lucifer Yellow derivative can react with aldehyde-containing molecules to form hydrazone bonds.

Red Sodium Cobalti-nitrite, 2Na2O.Co203.4N203.—To obtain this salt, nitrous acid is added to a suspension of cobalt carbonate in the requisite quantity of sodium nitrite solution until a reddish brown colour is attained. The liquor is evaporated by exposure over sulphuric acid, leaving a reddish brown crystalline powder of the above composition.4 Alcohol does not precipitate this salt from its aqueous solution, neither is a precipitate obtained with a soluble potassium salt. In both these features, therefore, the red sodium cobalti-nitrite differs from the yellow salt already described. Continued treatment with nitrous oxide converts the red salt into the yellow derivative. 

The tetramethylethylenediamine gave the yellow-orange LXXI (M = Pd,X = Cl) and the deep orange LXXI (M = Pd,X = Br) both these compounds could be recrystallized unchanged from water even when it contained an excess of the free diamine. The diamine gave the pale yellow derivatives, LXXI (M = Pt, X = Cl) and LXXI (M = Ir, X = Cl), and the two deep green copper(II) derivatives, LXXI (M = Cu, X =... 

Dinitrophenylhydrazones. All aldehydes and ketones readily form bright-yellow to dark-red 2,4-dinitrophenylhydrazones. Yellow derivatives are formed from isolated carbonyl groups and orange-red to red derivatives from aldehydes or ketones conjugated with double bonds or aromatic rings. 

Penicillin V may be nitrated by 10% potassium nitrate in concentrated sulfuric acid 72, HO. The yellow derivative in ammonia solution can be determined colorimetrically. Birner s 72 method estimates both penicillin V and phenoxyacetic acid in fermentation broths. Selectivity is achieved by solvent extraction techniques. 

The reaction with the amino acid proline results in a yellow derivative. The amount of each amino acid is then determined by measuring the absorption of light by the ninhydrin derivatives. 

The formation of xanthylium pigments may also result from non enzymatic reactions of colorless precursors such as flavanols as previously reported (/various oxidation processes. In the presence of tartaric acid and iron or copper ions, yellow pigments with absorption maxima at 440 and 460 nm were formed along with the colorless (+)-catechin carboxymethine bridged dimers 46, 47). These pigments were analysed by ID and 2D NMR and identified as non esterified and esterified xanthylium salts respectively 33, 38, 39, 42) (Figure 5). 

A third yellow derivative, quinacridonequinone (XV), made as shown in Scheme V or directly from the oxidation of quinacridone, is also not weatherfast by itself. However, chemists at Du Pont found that solid solutions of the quinone with quinacridone leads to pigments with improved fastness properties (30-32). 

Figure 35 Comparison between the ligand-binding site (stereoview) of (a) the transient penta-coordinated cadmium (green)-substituted LADH in ternary complex with the inhibitor DMSO (131) (orange) and NADH (pink) (PDB ID 2JHF), showing coordination with OH" ion (yellow) derived from a water molecule and (b) tetrahedrally coordinated zinc (gray) in liver sorbitol dehydrogenase ternary complex with the inhibitor IBA (132) (green) and NADH (pink) (PDB ID 2JHG).

The simpler nitrogenous constituents of wort consist principally of a-amino acids which can be estimated by the colour reaction either with indane-1,2, 3-trione hydrate (ninhydrin) or 2,4,6-trinitrobenzenesulphonic acid. With ninhydrin, a-amino acids develop a violet colour which can be measured at 570 nm while proline, an important imino acid in wort and beer, gives a yellow colour measured at 440 nm. 2,4,6-Trinitrobenzenesulphonic acid is more specific, for amino acids and does not react with proline or ammonia. It forms yellow derivatives which can be estimated colorimetrically at 340 nm. 

The yellow derive, have the stractore II, whilst the colourless derivs have the stractore I. 

Crystals (AcOH), mp 179.5-180.5 °C (dec.) React KOH yellow, PD yellow Deriv Methyl 5-chlorohaematommate, mp 155 °C, from 5-chlorohaematommic acid with the equivalent amount of CH2N2 in Et20 at 0 °C Lit Roller and Popl 1934a,b... 

Needles (MeOH-H O), mp 163-164 °C React FeClj (EtOH) red, PD yellow Deriv Methyl 2-methoxy-4-hydroxy-5-formyl-6-methylbenzoate, needles, mp 135 °C (EtOH), from 2-methoxy-4-hydroxy-5-formyl-6-methylbenzoic acid with the calculated amount of CHjNj in EtjO at 0°C... 

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