Influence of hydrogen bonds on charge distribution and conformation of L-arginine

Guanidine-phosphate non-covalent interaction in LAP crystal growth solution evidenced from spectroscopy studies

The similar L-arginine molecule aggregation has been found in L-arginine (LA) and L-arginine phosphate monohydrate (LAP) aqueous solutions. The special fluorescence emission at 380 nm of LA aggregates in LAP solution has been found, compared with the emission of LA solution at 415 nm, which has an obvious blue shift. By comparing the fluorescence spectra of several solutions for L-arginine and L-lysine salts, the interaction between phosphate and guanidine in LAP solution was considered to be the cause of its special fluorescence emission. Meanwhile, when LAP molecule formed in solution, the fluorescence emission wavelength and the UV absorption intensity at 296 nm of L-arginine solutions have mutated. Therefore, the group interaction involved by guanidine has changed the fluorescence properties of L-arginine aggregates in LAP solution, indicating that the specific interaction between phosphate and guanidine exists in LAP molecule.

L-arginine trifluoroacetate salt bridges in its solid state compound: the low-temperature three dimensional structural determination of L-arginine bis(trifluoroacetate) crystal and its vibrational spectral analysis

Structural varieties of L-arginine trifluoroacetate (abbreviated as LATF) and L-arginine bis(trifluoroacetate), LABTF, in the solid state compounds were observed and analyzed by the nuclear magnetic resonance (NMR) spectroscopy. The guanidinium-carboxylate interaction plays an important role involving in the crystal structure construction. Conformational changes of L-Arg(+) and L-Arg(2+) cations result from the intrinsic structural difference by hydrogen bonding and electrostatic interactions. The low-temperature structure of its crystalline salt, L-arginine bis(trifluoroacetate), was determined to describe the hydrogen bonding interactions. In comparison with the crystal structure at room temperature, the low-temperature L-Arg(2+) cations present tiny conformational difference and the rotational disorder of CF(3) group disappears. FT-IR and Raman spectra were investigated and hydrogen bonding interactions were analyzed on the basis of its vibrational spectra. Results indicate that this type interaction is greatly contributive to the structural features and vibrational spectral properties.

Identification of poly(ADP-ribose) polymerase-1 as the OXPHOS-generated ATP sensor of nuclei of animal cells

Our results show that in the intact normal animal cell mitochondrial ATP is directly connected to nuclear PARP-1 by way of a specific adenylate kinase enzymatic path. This mechanism is demonstrated in two models: (a) by its inhibition with a specific inhibitor of adenylate kinase, and (b) by disruption of ATP synthesis through uncoupling of OXPHOS. In each instance the de-inhibited PARP-1 is quantitatively determined by enzyme kinetics. The nuclear binding site of PARP-1 is Topo I, and is identified as a critical "switchpoint" indicating the nuclear element that connects OXPHOS with mRNA synthesis in real time. The mitochondrial-nuclear PARP-1 pathway is not operative in cancer cells.