Sulfhydryl functionality

PDPH also may be used as a thiolation reagent to add sulfhydryl functional groups to carbohydrate molecules. The reagent can be used in this sense similar to the protocol described for AMBH (Chapter 1, Section 4.1). After modification of an oxidized polysaccharide with the hydrazide end of PDPH, the pyridyl group is removed by treatment with DTT, leaving the exposed sulfhydryl (Figure 5.15). 

Fig. 9. Fluorine-18-labelled A/-substituted maleimides for coupling to peptides and proteins via sulfhydryl functions.

Cysteine An amino acid with a sulfhydryl functional group. 

Vicinal dithol Two sulfhydryl functional groups bonded to adjoining carbons (e.g. HSCH2CH2SH). 

Among the various sulfur nucleophiles which are encountered in natural waters, most are Bronsted acids or bases, i.e., they can accept or lose a proton. The sulfhydryl functional group is a monoprotic Bronsted acid, while H2S and H2SO3 are diprotic Bronsted acids. The rate of displacement of halide from a given substrate in aqueous solution containing a nucleophilic Bronsted acid depends upon the relative concentrations among the different protonated forms of the acid (of which there are two for a monoprotic acid, three for a diprotic acid), as well as the respective rates of reaction of the different protonated... 

Sulfhydryl functionality—for example, cysteine (C) and methionine (M), of which cysteine is noted for its easy formation of disulfide linkages and its... 

Ketone 2 and its metabolite chloro-acetone (16) are alkylating agents. This property is of special importance, when the substrate is being reduced stereoselectively by reductases with an essential sulfhydryl function. Because the sulfhydryl groups are inhibited irreversibly by alkylation [69], stereoisomer distribution in the product is considerably affected. 

The sulfhydryl functional group of Cys is an excellent nucleophile and is easily acylated or alkylated hence it must be protected during SPPS. Oxidation to form the disulfide may also occur if Cys is left unprotected. Many of the suggested protecting groups are compatible with both Boc and Fmoc SPPS as they are not base or acid labile. 

As interpreted in Scheme 12, a sterically shielded, bifunctional model substrate containing a methyl thioether and sulfhydryl functional group could form a five-membered... 

Finally, Section C of Fig. 17 summarizes some of the important CNS species and related compounds which definitely are not electrochemically active. Neither ACh, GABA, nor any of the amino acids (except tyrosine and glutathione, as mentioned earlier) are electroactive. Many drugs like amphetamine and / -chloroamphetamine are innocuous from the electrochemical viewpoint. As a rule of thumb, any drug having an aromatic hydroxyl, amino or sulfhydryl function, or a phenothiazine-like structure may be electro-oxidizable. However, it is always advisable to check the electrochemistry of any new drug. 

In 2015, organic solvent soluble AuNPs stabilized by mono-sulfhydryl functionalized pillar[5]arene (SH-P5) were prepared by Zhou et al. [31] Quaternary ammonium salt functionalized anthracene has reversible noncovalent host-guest interactions with SH-P5, which can lead to reversible assembly of AuNPs. Based on photo [4-f 4] cycloaddition of anthracene, they can reversibly aggregate and disassemble by variation of the temperature and/or photo-irradiation, and can catalyze borohydride reduction of 2,6-dichloro-4-nitrophenol. 

Rhodanese is a sulfhydryl enzyme and it is tempting to formulate the reaction of rhodanese with thiocystine in terms of sulfhydryl function. The reaction should be formulated as follows ... 

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