Patterns of cation binding to the aromatic amino acid R groups in Trp, Tyr, and Phe.

Previous joint experimental and theoretical work demonstrates that typically soluble peptides will be rendered insoluble in the presence of saturated sodium ions in aqueous solution due to disruption of cation-π interactions between Trp and Lys. The present work utilizes quantum chemical methods including density functional theory, symmetry-adapted perturbation theory, and even coupled cluster theory to determine the strengths of cation-π interactions for the aromatic R groups of Trp, Tyr, and Phe (approximated as skatole, methyl phenol, and toluene) with both alkali and alkaline-Earth atomic cations and electron-accepting R groups from Lys, Arg, and His approximated as methyl ammonium, guanidinium, and imidazolium cations. This work shows that sodium ion is still the most likely disrupter of peptide folding built upon cation-π interactions, since Trp, Tyr, and Phe all bind more strongly to sodium ion than to any of the polyatomic cations.

Circular dichroism spectroscopy: Enhancing a traditional undergraduate biochemistry laboratory experience.

The undergraduate biochemistry laboratory curriculum is designed to provide students with experience in protein isolation and purification protocols as well as various data analysis techniques, which enhance the biochemistry lecture course and give students a broad range of tools upon which to build in graduate level laboratories or once they begin their careers. One of the most common biochemistry protein purification experiments is the isolation and characterization of cytochrome c. Students across the country purify cytochrome c, lysozyme, or some other well-known protein to learn these common purification techniques.

Hippocampal acetylcholine depletion has no effect on anxiety, spatial novelty preference, or differential reward for low rates of responding (DRL) performance in rats.

We investigated the role of the septo-hippocampal cholinergic projection in anxiety, spatial novelty preference, and differential reward for low rates of responding (DRL) performance. Cholinergic neurons of the rat medial septum (MS) and the vertical limb of the diagonal band of Broca (VDB) were lesioned using the selective immunotoxin, 192 IgG-saporin. Rats were then tested on several behavioral tests previously shown to be sensitive to either (a) hippocampal lesions or (b) nonselective MS/VDB lesions which target both cholinergic and γ-aminobutyric acid (GABA)-ergic projections, or both.

Effects of psychotropic agents on extinction of lever-press avoidance in a rat model of anxiety vulnerability.

Avoidance and its perseveration represent key features of anxiety disorders. Both pharmacological and behavioral approaches (i.e.

The role of the hippocampus in avoidance learning and anxiety vulnerability.

The hippocampus has been implicated in anxiety disorders and post-traumatic stress disorder (PTSD); human studies suggest that a dysfunctional hippocampus may be a vulnerability factor for the development of PTSD. In the current study, we examined the effect of hippocampal damage in avoidance learning, as avoidance is a core symptom of all anxiety disorders. First, the effect of hippocampal damage on avoidance learning was investigated in outbred Sprague Dawley (SD) rats.

Medial septum-diagonal band of Broca (MSDB) GABAergic regulation of hippocampal acetylcholine efflux is dependent on cognitive demands.

The septohippocampal pathway contains cholinergic, GABAergic, and glutamatergic projections and has an established role in learning, memory, and hippocampal theta rhythm. Both GABAergic and cholinergic neurons in the medial septum-diagonal band of Broca (MSDB) have been associated with spatial memory, but the relationship between the two neuronal populations is not fully understood. The present study investigated the effect of selective GABAergic MSDB lesions on hippocampal acetylcholine (ACh) efflux and spatial memory during tasks that varied in memory demand.

Structural insights into the calcium-dependent interaction between calbindin-D28K and caspase-3.

The regulation of apoptosis involves a complicated cascade requiring numerous protein interactions including the pro-apoptotic executioner protein caspase-3 and the anti-apoptotic calcium-binding protein calbindin-D28K. Using isothermal titration calorimetry, we show that calbindin-D28K binds caspase-3 in a Ca(2+)-dependent fashion. Molecular docking and conformational sampling studies of the Ca(2+)-loaded capase-3/calbindin-D28K interaction were performed in order to isolate potentially crucial intermolecular contacts.

Nitric oxide-dependent killing of aerobic, anaerobic and persistent Burkholderia pseudomallei.

Burkholderia pseudomallei infections are fastidious to treat with conventional antibiotic therapy, often involving a combination of drugs and long-term regimes. Bacterial genetic determinants contribute to the resistance of B. pseudomallei to many classes of antibiotics.

Adaptation and antibiotic tolerance of anaerobic Burkholderia pseudomallei.

The Gram-negative bacterium Burkholderia pseudomallei is the etiological agent of melioidosis and is remarkably resistant to most classes of antibacterials. Even after months of treatment with antibacterials that are relatively effective in vitro, there is a high rate of treatment failure, indicating that this pathogen alters its patterns of antibacterial susceptibility in response to cues encountered in the host. The pathology of melioidosis indicates that B.

Redesign of a WW domain peptide for selective recognition of single-stranded DNA.

A β-sheet miniprotein based on the FBP11 WW1 domain sequence has been redesigned for the molecular recognition of ssDNA. A previous report showed that a β-hairpin peptide dimer, (WKWK)(2), binds ssDNA with low micromolar affinity but with little selectivity over duplex DNA. This report extends those studies to a three-stranded β-sheet miniprotein designed to mimic the OB-fold.

Structural effects on ss- and dsDNA recognition by a beta-hairpin peptide.

FORM DEFINES FUNCTION: The effects of beta-hairpin structure on the binding affinity and selectivity for ssDNA versus dsDNA were investigated; this provided insights into the factors that contribute to the selective recognition of both ss- and dsDNA and suggested new approaches for designing biomimetic receptors. Binding studies showed that 1) folding is crucial for binding to both ss- and dsDNA, and 2) chirality affects binding for duplex but not for ssDNA.The interactions involved in the binding of a designed beta-hairpin dimer to single-stranded and duplex DNA have been explored.

Inactivation of [Fe-S] metalloproteins mediates nitric oxide-dependent killing of Burkholderia mallei.

Background: Much remains to be known about the mechanisms by which O(2)-dependent host defenses mediate broad antimicrobial activity.

Methodology/principal Findings: We show herein that reactive nitrogen species (RNS) generated by inducible nitric oxide (NO) synthase (iNOS) account for the anti-Burkholderia mallei activity of IFNgamma-primed macrophages. Inducible NOS-mediated intracellular killing may represent direct bactericidal activity, because B.

Lack of immune responses to Mycobacterium tuberculosis DosR regulon proteins following Mycobacterium bovis BCG vaccination.

Mycobacterium bovis BCG is widely used as a vaccine against tuberculosis (TB), despite its variable protective efficacy. Relatively little is known about the immune response profiles following BCG vaccination in relation to protection against TB. Here we tested whether BCG vaccination results in immune responses to DosR (Rv3133c) regulon-encoded proteins.