Specific labeling

Sometimes the strongly basic properties of Gngnard reagents can be turned to synthetic advantage A chemist needed samples of butane specifically labeled with deuterium the mass 2 isotope of hydrogen as shown... 

Numeric-to-symbohc transformations are used in pattern-recognition problems where the network is used to classify input data vectors into specific labeled classes. Pattern recognition problems include data interpretation, feature identification, and diagnosis. 

In Division 1 areas, meters, instruments, relays, and similar equipment containing high-temperature or arcing devices must be installed in approved explosion-proof or purged enclosures. Unless such devices are specifically labeled as suitable for Class I, Division 1 areas, it is best to assume they are not suitable. 

When specifically labelled compounds are required, direct chemical synthesis may be necessary. The standard techniques of preparative chemistry are used, suitably modified for small-scale work with radioactive materials. The starting material is tritium gas which can be obtained at greater than 98% isotopic abundance. Tritiated water can be made either by catalytic oxidation over palladium or by reduction of a metal oxide ... 

Of more chemical interest is the synthesis of radioactive " C compounds from " C02 which is conveniently stored as a carbonate. " C is generated by an (n,p) reaction on a nitride or nitrate in a nuclear reactor (see p. 1256). More than 500 compounds specifically labelled with " C are now available commercially, the starting point of many of the syntheses being one of the following reactions ... 

However, an elegant O nmr study using specifically labelled [CoINHslsl ONO)] " and (Co(NH3)5(ON 0)] established that spontaneous intramolecular O-to-O exchange in the nitrite ligand occurs at a rate comparable to that of the spontaneous O-to-N isomeri /ation/ ° ... 

Brandenberger and later, independently, Canellakis and Cohen, and Hartman and Fellig studied the course of the oxidation with uric acid specifically labeled with On the basis of their work they formulated the course of the oxidation as shown in Scheme 1. 

A mixture of d- and l- hexoses also results from the hydroboration of these 5-enes. Hydroboration results in anti-Markownikoff, cw-hydration of the double bond and the amount of each hexose formed varies according to the nature of the substituent groups. For example, hydroboration (23) of methyl 6-deoxy-a-D-ryZo-hex-5-enopyranose (3) affords methyl a-D-glucopyranoside and methyl / -L-idopyranoside in the ratio of 1 2.5 respectively whereas hydroboration of the fris-trimethylsilyl ether of 3 afforded them in the ratio 1 0.6 respectively. The hydroboration method can be used to achieve specific labelling of hexoses with tritium methyl-/ -L-idopyranoside[5-H3] and methyl a-D-glucopyranoside [5-H3] were thus prepared (23). Similarly, hydroboration of the D-Zt/ro-hex-5-eno derivative (14) with diborane-H3 followed by removal of the isopropyli-dene group, afforded methyl a-D-mannopyranoside [5-H3] and methyl / -L-gulopyranoside [5-H3] in the ratio of 1 2 respectively (23). 

The related 3-deoxy-D-waHnooctulosonic acid aldolase (KDO aldolase F.C 4.1.2.23) likewise suffers from an unattractive equilibrium constant but allows a simple synthesis of specifically labelled KDO from D-arabinose and labelled pyruvate28. 

Peracetic acid specifically labelled with oxygen-18 has been used for the oxidation of (+ )-benzyl-p-tolyl sulphoxide to the (— )-[160180]sulphone46 (equation 15). The reaction gives the required enantiomer in no less than 80% yield. 

Yellow 5 and 6 are widely used in candies and drug coatings. Orange B is used in hot dog and sausage casings. Some people are sensitive to Yellow 5 reactions to it can be severe enough that specific labeling is required for prescription medicines that contain it. None of the other certified dyes have this special requirement. 

Preparation of Specifically Labeled Samples of 5-Amino-1 -(P-D-ribofuranosyl)imida-... 

Further work demonstrated that the three missing atoms came from the ribose part of AIR. For this, it was necessary to prepare samples of AIRs specifically labeled on the ribose part. The methods are described in the following section. 

Scheme 28.—The seven specifically labeled AIRs prepared. The sites of labeling are indicated with the labeled atoms in bold type.

The six specifically labeled AIRs prepared by the foregoing methods are shown in Scheme 28. 

Because sugars are involved in most of the mechanisms established for the synthesis of these heterocycles, the development of carbohydrate chemistry has been most helpful in these researches—especially for the preparation of specifically labeled molecules. Conversely, the contribution of these efforts to carbohydrate chemistry and biochemistry has shown the involvement in biosynthesis of 1 -deoxy-D-f/rreo-pentulose—scarcely before recognized and considered a rare sugar—and of fully functionalized pentuloses of still unknown configuration (or their phosphates). Finally, evidence has been found in prokaryotes for a most extraordinary transformation of 5-amino-l-(P-D-ribofuranosyl)imidazole 5 -phos-phate into a pyrimidine. Surely, this transformation should be explained in terms... 

Immunogold labeling with JIM S exhibited an identical labeling distribution for polygalacturonic acid as was obtained indirectly with the EPG EMSIL (inset of Fig. 1). Control experiments for labeling specificities obtained by the direct or indirect methods resulted in total elimination of specific labeling. The cellulase-gold probe heavily labeled the epidermal cell walls (Fig. 2). 

Pintacuda, G., Moshref, A., Leonchiks, A., Sharipo, A., Otting, G. Site-specific labeling with a metal chelator for protein-structure refinement. /. Biomol. NMR 2004, 29, 351-361. 

G. Site-specific labeling of proteins with a rigid lanthanide-binding tag. ChemEioChem 2006, 7,1599-1504. 

The acetylcholine receptor (AChR) of Torpedo electric organ is also a PCP "receptor." However, this nicotinic AChR has about one-tenth the affinity for PCP than that of the rat brain PCP receptor [K0.5 = 0.3 pM, versus = 4-6 pM for Torpedo (Heidmann et al. 1983 flaring et al. 1984)]. Moreover, the nicotinic AChR has subunits of MR<66 kD, and these are the subunits that are specifically labelled with 3H-Az-PCP in the Torpedo electroplax membranes (Heidmann et al. 1983 Haring and Kloog 1984 Haring et al. 1984). These data indicate that the nicotinic AChR-PCP receptor differs from the rat brain PCP receptor. Furthermore, our findings are... 

---