Combination tables thiols

The dynamic features of each of the thiols were subsequently evaluated in transthiolesterification reactions in buffered D O solution (NaOD/D PO, pD 7.0) with the ACh analog acetylthiocholine [ASCh (14), Table 6.1]. Formation/thiolysis of each thiolester was carefully followed by H-NMR spectroscopy at different time intervals, and exchange rate and equilibrium composition were determined for each combination. The rate of exchange was directly correlated to the p/f of the thiols the lower the pK, the faster the exchange reaction (Table 6.1). Thiols having pK values lower than 8.5 reached equilibrium very rapidly. The results also showed that the majority of thiols produce equilibrium concentrations that are close to... 

It has been shown above that there is a marked effect of the charge of the thiol and its efficiency to protect against OH attack but also to repair DNA damage (for thiol binding to DNA see Smoluk et al. 1986). An extension to GSH-deficient cells in combination with the oxygen explosion technique allowed to determine the rate constants of various thiols with radiation-induced DNA damage (Table 12.21 Prise et al. 1995). 

Chen and co-workers later reported the successful asymmetric 1,4-addition of aryl thiols to a,/ -unsaturated cyclic enones and imides using Takemoto s elegantly simple catalyst (3) [43]. This bifunctional amine-thiourea catalyst gives optimal reactivity and reproducibility when used at 10 mol% loading in the presence of freshly dried 4 A molecular sieves (MS). This combination afforded the expected addition products in high yields (90-99%) and moderate to good enantioselectiv-ities (55-85% ee) for a variety of cyclic and acyclic Michael acceptors (Table 6.2). 

Cys residues in eAspAT. Only Cys-191 is conserved among mammalian and K coli AspAT. The other four Cys residues in K coli do not have any homology with the mammalian enzymes, except for Cys-82, which is found in pig c Asp AT (Table 5.4). They mutated all five Cys residues individually and in combinations, and found that all Cys mutants showed the proper function and stability.65 Thus, it is unlikely that any of the five Cys residues are involved in the folding process. There are several Cys residues found in mAspAT. Among them, Cys-166 is the only thiol group exposed in the spatial structure of the protein. Giannattasio et al.6 have proposed a hypothesis that Cys-166 in mAspAT may be involved in the import mechanism of this isozyme which must be transported into mitochondria. 

In the uncondensed imidazoles the standard method reacts an a-aminocarbonyl compound with a thiocyanate (see Section 4.1 and Table 4.1.1). If a 2-alkylthioimidazole is required directly, one can combine an N-alkyT or A -arylcarbonimidodithioate in refluxing acetic acid with the aminocarbonyl substrate (see Section 4.1 and Scheme 4.1.3). Alternatively, reaction between thiourea and a two-carbon synthon (ot-hydroxy-, a-halogeno-, a-dicarbonyl) leads to imidazoline-2-thiones (see Section 4.3). In sulfuric acid, 3-butynylthiourea cyclizes to 4,5-dimethylimidazolin-2-thione (see Section 2.2.1). 1-Substituted 2-methylthioimidazoles can be made, albeit in rather poor yields, from appropriately substituted 2-azabutadienes (see Section 3.2 and Scheme 3.2.3), and 2-arylthioimidazoles are available in moderate yields from benzyl isocyanides and arylsulfenyl chlorides (see Section 4.2 and Scheme 4.2.12). Ring transformations of 5-amino-2-alkylaminothiazoles and 2-acylamino-5-aminothiazoles may have occasional applications (see Section 6.1.2.7). The ease with which a thiol group or imidazole or benzimidazole can be alkylated, in comparison with the annular nitrogens, usually makes it more convenient to prepare alkylthioimidazoles from the thiols (or thiones). 

As previously discussed, the stepwise formation constant for the addition of a third thiol or thiolate ligand to Hg(SR)2 compounds range from —10 to 10 (Tables VIII and IX). In thiol buffered solutions of micromolar protein concentrations, MerR has been shown to bind Hg(II) at least 10 times better than the competing buffer thiols (82, 171, 210). A combination... 

The most important combinations of epoxy resins and curing agents are summarized in Table 2.6. Depending on their molecular mass, bisphenol A epoxy resins can be cured by polyaddition via their epoxy or hydroxyl groups. Polyamines, poly thiols, and polyisocyanates are suitable for room temperature cure. Polyanhydrides, polyphenols, acids, and carboxy-functional polyesters are suitable for hot cure. 

A special case of combination of amine catalysis and solvent effect is givetf by the easy oxidation of aliphatic and aromatic thiols in tetra-methylguanidine which acts both as base and as a dipolar aprotic solvent (see Table 14). 

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