Pyridine-2-thiol, complexes with complex

Boric acid forms complexes with a number of inorganic ions and organic molecules. Ammonia, hydrazine, hydroxides and oxyhalides from complexes with boric acid. The organics include diols, thiols, dioxane, pyridine and many other solvents in which boric acid dissolves. 

With pyridine/S03 complex at higher temperatures (70-80 °C), in addition to sulfation of phenolic, hydroxy, and thiol groups, sulfation of amino, guanidino, and primary amido... 

Protection of the reductase by NADH from inhibition by thiol group reagents suggested that the enzyme formed a stable complex with pyridine nucleotide (353). Such a complex was readily demonstrated by difference spectroscopy. When the enzyme was reduced by NADH or AcPyADH a prominent positive band was observed at 317 nm (Fig. 16) this band was very small (and blue-shifted) when NADPH, a very poor substrate, was the reductant. Furthermore, addition of NAD+ following NADPH resulted in a difference spectrum identical with that produced by NADH. The dashed line in Fig. 15 represents the absorption resulting from NAD" binding. Thus, this band was attributed to a reduced enzyme-NAD complex (350). 

A hydrogen-bond acidity scale has been constructed by Frange and coworkers and by Sraidi based on log K values for complexation with pyridine N-oxide in cyclohexane (equations 22 and 23). Values for phenols and, for comparison, thiols, chloroform, pyrrole and alcohols are collected in Table 5. There is a fair measure of agreement between log K and log Kf n = 16, r = 0.992) and log (n=9,r = 0.972). 

Besides their affinity for metallic ions, thiol groups have other characteristics such as ability to interconvert to disulfides through redox reactions, to add to conjugated double bonds and to form complexes with the pyridine nucleotides by nucleophilic attack at the 4-position of the pyridine ring. 

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