Thiols compounds

The reaction of ort/io-phthalaldehyde and a thiol compound with an amino acid to form an isoindole derivative can be used to enhance the detection sensitivity for the normally only weakly UV-detectable amino acid compounds, and to introduce an... 

The mixture of free amino acids is reacted with OPA (Fig. 7-8) and a thiol compound. When an achiral thiol compound is used, a racemic isoindole derivative results. These derivatives from different amino acids can be used to enhance the sensitivity of fluorescence detection. Figure 7-9 shows the separation of 15 amino acids after derivatization with OPA and mercaptothiol the racemic amino acids may be separated on a reversed-phase column. If the thiol compound is unichiral, the amino acid enantiomers may be separated as the resultant diastereomeric isoindole compound in the same system. Figure 7-10 shows the separation of the same set of amino acids after derivatization with the unichiral thiol compound Wisobutyryl-L-cysteine (IBLC). 

Fig. 7-8. Derivatization of amino acids with OPA and a thiol compound.

Dehydrocoelenterazine (D) forms an addition product (E) when treated with acetone in the presence of benzylamine (Takahashi and Isobe, 1993). Thiol compounds, such as DTT (dithiothreitol) and glutathione, also add to D, forming an equilibrium mixture containing F (Takahashi and Isobe, 1994). These adducts are chemiluminescent. 

Clinical trials showed therapeutic efficacy in a broad spectrum of tumors these include SCLC, testicular tumors, sarcomas, breast cancer, renal cell cancer, pancreatic tumors and lymphomas. Ifosfamide is less myelosuppressive than cyclophosphamide but is more toxic to the bladder. Therefore it is recommended that ifosfamide is coadministered with the thiol compound mesna to avoid hemorrhagic cystitis and to reduce the risk of developing bladder cancer. Other side effects include neurotoxicity and myelosuppression. 

Thiol compounds 252, 254 Thione compounds 252, 254 Thiosemicarbazides, N-aryl- 248 Thiourea 107, 246,254, 269, 337 -, derivatives 322, 323 Thorium cations 144 Threonine 246 Thymol 153, 197, 198 -, derivatives 288 Tigogenin 59, 195 -, acetate 63 Tigogenone 59,60 Tillmans reagent 256 Tin, cations 144,311,398 -, organic derivatives see Organotin compounds... 

PBE dendrons coordinate to the surface of II-VI semiconductor nanocrystals (e.g., CdSe [33] and CdSe/ZnS core/shell structure [34, 35]) to modulate the photoluminescence of the nanocrystals [32]. Trioctylphosphine oxide (TOPO)-capped II-VI semiconductor nanocrystals of several-nanometers diameter have been synthesized by a pyrolysis reaction of organometallics in TOPO [33-35]. The capping ligand (TOPO) can be replaced by stronger ligands such as thiol compounds [36], suggesting that dendrons bearing sulfur atom(s) at the focal point replace TOPO as well. 

Mercuric chloride, other mercury-containing antibacterials and silver will inhibit enzymes in the membrane, and for that matter in the cytoplasm, which contain thiol, -SH, groups. A similar achon is shown by 2-bromo-2-nitropropan-l,3-diol (bronopol) and iso-thiazolones. Under appropriate condihons the toxic action on cell thiol groups may be reversed by addition of an extrinsic thiol compound, for example cysteine or thioglycollic aeid (see also Chapters 12 and 23). 

A methacryl-type polyester macromonomer was synthesized by lipase PF-catalyzed polymerizahon of DDL using vinyl methacrylate as terminator ( terminator method ), in which the vinyl ester terminator was present from the beginning of the reachon (Scheme 17). In using divinyl sebacate as terminator, the telechelic polyester having a carboxylic acid group at both ends was obtained. Various non-protected thiol compounds were used as inihator or terminator for the thiol end-funchonalizahon of poly(8-CL). ... 

For transition and precious metals, thiols have been successfully employed as the stabilizing reagent (capping reagent) of metal nanoparticles [6]. In such cases, various functionalities can be added to the particles and the obtained nanoparticles may be very unique. It is well known that thiols provide good self-assembled monolayers (SAM) on various metal surfaces. When this SAM technique is applied to the nanoparticle preparation, nanoparticles can be covered constantly by functionalized moieties, which are connected to the terminal of thiol compounds. 

In 1994, thiols were firstly used as stabilizers of gold nanoparticles [6a]. Thiols form monolayer on gold surface [18] and highly stable nanoparticles could be obtained. Purification of nanoparticles can be carried out, which makes chemical method of metal nanoparticles a real process for nanomaterial preparation. Various thiol derivatives have been used to functionalize metal nanoparticles [6b, 19]. Cationic and anionic thiol compounds were used to obtain hydrosols of metal nanoparticles. Quaternary ammonium-thiol compounds make the nanoparticle surface highly positively charged [20]. In such cases, cationic nanoparticles were densely adsorbed onto oppositely charged surfaces. DNA or other biomolecule-attached gold nanoparticles have been proposed for biosensors [21]. 

In this study, three a,stabilizing reagent of gold nanoparticles (Figure 3). 

HaddcKk, P.S. (1991). Thiol compounds and their effects on ionic homeostasis in the isolated rat heart. Ph.D. thesis. University of Bath. 

Separation of Amino Acid Enantiomers after Derivatization with Ortho-Vh ( ha I di a I dehyde (OPA) and a Unichiral Thiol Compound 193... 

Skunks deter predators by release of a liquid spray containing seven major volatile components classified as thiols (compounds containing the -SH functional group) and acetate derivatives of thiols (characterized by the SC(0)CH3 functionality). In particular, two of the more odiferous components responsible for the strongly repellent odor of the skunk s secretion are 2-butene-1-thiol (Fig. 13.2.1) and 3-... 

To deodorize a pet sprayed by a skunk, the noxious compound must be converted to an odorless one. Using an alkaline solution of 3% hydrogen peroxide and sodium bicarbonate, the thiol compound (denoted R-SH) can be oxidized to a disulfide compound,... 

Figure 1.78 TCEP reduction of disulfides proceeds without the use of thiol compounds.

Figure 5.9 SIAX can be used to modify amine-containing molecules to produce sulfhydryl-reactive derivatives. Subsequent reaction with a thiol compound produces a thioether linkage.

Figure 5.11 NPIA is one of the shortest heterobifunctional reagents. It reacts with amine-containing molecules through its p-nitrophenyl ester end to produce amide bonds. The iodoacetyl group then can be used to couple with thiol compounds to give stable thioether linkages.

Peptides typically are prepared for this ligation process using a-alkyl thioesters, because they are simple to make at the time of peptide synthesis. However, due to the relatively slow reaction kinetics of alkyl thioesters, most native chemical ligation processes have been catalyzed through the use of thiol compound additives, such as benzyl mercaptan or thiophenol (Dawson et al., 1997). These compounds react with the initial a-alkyl thioester to form another intermediate, an aryl thioester, which is more reactive toward the N-terminal cysteine on the other peptide to be coupled. A study... 

Figure 22.13 MBS reacted with PE produces a maleimide derivative that can couple to thiol compounds through a stable thioether bond.

M.C. Liu, P. Li, Y.X. Cheng, Y.Z. Xian, C.L. Zhang, and L.T. Jin, Determination of thiol compounds in rat striatum microdialysate by HPLC with a nanosized CoHCF-modified electrode. Anal. Bioanal. Chem. 380, 742 (2004). 

As compounds exhibiting enhancing effects on CL reactions, a variety of phenols, e.g., firefly luciferin and 6-hydroxybenzothiazole derivatives [12,13], 4-iodophe-nol [14], 4-(4-hydroxyphenyl)thiazole [15], 2-(4,-hydroxy-3 -methoxy-benzyli-dene)-4-cyclopentene-l,3-dione (KIH-201) [16], and 2-(4-hydroxyphenyl)-4,5-diphenylimidazole (HDI) and 2-(4-hydroxyphenyl)-4,5-di(2-pyridyl)imidazole (HPI)[17] (Fig. 6A), and phenylboronic acid derivatives, e.g., 4-phenylylboronic acid [18], 4-iodophenylboronic acid [19], and4-[4,5-di(2-pyridyl)-l //-imidazol-2-yl]phenylboronic acid (DPPA) [20] (Fig. 6B), in the luminol/hydrogen peroxide/peroxidase system are well known. Rhodamine B and quinine are used as sensitizers in the CL-emitting reaction between cerium (IV) and thiol compounds. This CL reaction was successfully applied to the sensitive determination of various thiol drugs [21-32],... 

Purified mtALDH catalysed the stoichiometric formation of 1,2-GDN and nitrite from GTN, in a reaction that was shown to be dependent on the presence of thiols. It was argued that reductive denitration of GTN involves interaction of one of two adjacent active site thiols with GTN to yield an -SNO2 group, which then reacts with the other thiol to yield nitrite and a disulfide. In a final, essential step the inactive disulfide is converted back to two thiols by external thiol compounds (Scheme 2.2). It is interesting to note that this mechanism is essentially that foreseen by Needleman and colleagues in their proposed nitrate receptor (see earlier). 

One of the most potent, selective inhibitors to date comes from a series of aliphatic sulfides which has been optimized for HDAC6 selectivity over HDACs 1 and 4. The best compound, 18, exhibits an IC50 of 29 nM against HDAC6 and ca. 35-40-fold selectivity, but as with the original thiol compounds, the sulfur atom needs to be acylated to achieve cellular activity [46]. 

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