The presence of an intramolecular hydrogen bond has been proposed to play a key role in the catalysis of amide isomerization by peptidylprolyl isomerases (PPIases), which are highly conserved and ubiquitous rotamase enzymes that catalyze the cis-trans isomerization of proline residues in peptides and proteins. We present herein kinetic and spectroscopic evidence that indicates the existence of ...

The electrochemical reduction of bisazo dye Direct Orange–31 has been studied at Pyrolytic graphite electrode (PGE) in the pH range 2.0–10.3. Two well-defined 4e–, 4H+ pH dependent reduction peaks (Ic & IIc ) have been observed in linear and cyclic sweep voltammetry. It has been observed that reduction of azo groups in the dye does not stop at hydrazo stage but further reduction leads to the cl...

A survey of leaf soluble amino acids was conducted for four subtropical seagrasses grown at several salinities. Proline functioned as an organic osmoticum in Halodule wrightii Aschers., Thallasia testudinum Banks ex Koenig, and Ruppia maritima L., while alanine functioned in an osmoregulatory capacity in Halophila engelmanni Aschers. When light-and salinity-induced variations in leaf NH(4) and ...

Amine precursors such as NH-Boc (5) and NH-formyl (6) protected glycines were grafted by esterification on the hy-droxylated arms of 1-(2-hydroxyethyl)-3-methylimidazolium hexafluorophosphates 4h or tetrafluoroborates 4t. The Boc cleav-age was then realized at room temperature by successively treating acetonitrile solutions of the carbamates 7h or 7t with methanol and acetyl chloride (2 equival...

The title compound, C(14)H(18)N(2)O(3)S, crystallizes in the thio-amide form with an intra-molecular N-H⋯O hydrogen bond associated with the thio-urea unit. With the benzoic acid and the butyrylthio-ureido units, the mol-ecule consists of two planar building blocks connected by the common NH function adjacent to the aromatic ring. The inter-planar angle is 33.38 (3)°. Mol-ecules are connected i...

The products of the reaction of ninhydrin with a-amino acids are, in general, the corresponding aldehyde of one less carbon atom than the original compound, COZ, and, at pH 5 to 7, an intensely colored compound (thought to be the anion of diketohydrindylidene-diketohydrindamine), which contains nitrogen from the amino acid. If the pH is kept at 2.5 or lower, this colored compound is not produce...

The reaction of silver nitrate with 5-chloro-2-hy-droxy-benzene-sulfonic acid in the presence of ammonia yielded the title salt, (NH(4))[Ag(NH(3))(2)](C(6)H(4)ClO(4)S)(2)·3H(2)O. The Ag(I) ion shows linear coordination [N-Ag-N = 175.2 (1) °]. The ammonium and diamminesilver cations, the benzene-sulfonate anion and the lattice water mol-ecules inter-act through an intricate network of N-H⋯O and ...

The effect of attaching the achiral, cyclic 1-aminocyclohexanecarboxylic acid (Ac6c) directly to aminoferrocene unit (Ac6c−NH−Fc) appears be a promising route for development new chiroptical sensor based on ferrocene chromophore. Three compounds (Boc−AA−Ac6c−NH−Fc; AA = L-Ala, L-Val, L-Phe) were synthesized, spectroscopically characterized (IR, NMR, CD), and conformationally analyzed (DFT). chi...