Systematic investigation of sequence and structural motifs that recognize ATP

Ratiometric Detection of ATP by Fluorescent Cyclophanes with Bellows-Type Sensing Mechanism

Pyrene-based cyclophanes have been synthesized with the aim to realize a bellows-type sensing mechanism for the ratiometric detection of nucleotide concentrations in a buffered aqueous solution. The sensing mechanism involves the encapsulation of a nucleobase between two pyrene rings, which affects the monomer-excimer equilibrium of the receptor in the excited state. The nature of the spacer and its connection pattern to pyrene rings have been varied to achieve high selectivity for ATP. The 1,8-substituted pyrene-based cyclophane with the 2,2'-diaminodiethylamine spacer demonstrates the best selectivity for ATP showing a 50-fold increase in the monomer-excimer emission ratio upon saturation with the nucleotide. The receptor can detect ATP within the biological concentrations range over a wide pH range. NMR and spectroscopic studies have revealed the importance of hydrogen bonding and stacking interactions for achieving a required receptor selectivity. The probe has been successfully applied for the real-time monitoring of creatine kinase activity.

Molecular Receptors for Recognition and Sensing of Nucleotides

Nucleotides are constituents of nucleic acids and they have a variety of functions in cellular metabolism. Synthetic receptors and sensors are required to reveal the role of nucleotides in living organisms and mechanisms of signal transduction events. In recent years, a large number of nucleotide-selective synthetic receptors have been devised, which utilize different molecular designs and sensing mechanisms. This Minireview presents recent progress in the design of synthetic molecular receptors for selective recognition of nucleotides in aqueous solution. The binding properties of receptors and the origins of their selectivity for a particular nucleotide are discussed.

Structural characterization of the intrinsically disordered domain of Mycobacterium tuberculosis protein tyrosine kinase A

Although intrinsically disordered proteins or protein domains (IDPs or IDD) are less abundant in bacteria than in eukaryotes, their presence in pathogenic bacterial proteins is important for protein-protein interactions. The protein tyrosine kinase A (PtkA) from Mycobacterium tuberculosis possesses an 80-residue disordered region (IDD_PtkA ) of unknown function, located N-terminally to the well-folded kinase core domain. Here, we characterize the conformation of IDD_PtkA under varying biophysical conditions and phosphorylation using NMR-spectroscopy. Our results confirm that the N-terminal domain of PtkA exists as an IDD at physiological pH. Furthermore, phosphorylation of IDD_PtkA increases the activity of PtkA. Our findings will complement future approaches in understanding molecular mechanisms of key proteins in pathogenic virulence.