Crystal Structure of the Minimalist Max-E47 Protein Chimera

Max-E47 is a protein chimera generated from the fusion of the DNA-binding basic region of Max and the dimerization region of E47, both members of the basic region/helix-loop-helix (bHLH) superfamily of transcription factors. Like native Max, Max-E47 binds with high affinity and specificity to the E-box site, 5′-CACGTG, both in vivo and in vitro. We have determined the crystal structure of Max-E47 at 1.7 Å resolution, and found that it associates to form a well-structured dimer even in the absence of its cognate DNA. Analytical ultracentrifugation confirms that Max-E47 is dimeric even at low micromolar concentrations, indicating that the Max-E47 dimer is stable in the absence of DNA. Circular dichroism analysis demonstrates that both non-specific DNA and the E-box site induce similar levels of helical secondary structure in Max-E47. These results suggest that Max-E47 may bind to the E-box following the two-step mechanism proposed for other bHLH proteins. In this mechanism, a rapid step where protein binds to DNA without sequence specificity is followed by a slow step where specific protein:DNA interactions are fine-tuned, leading to sequence-specific recognition. Collectively, these results show that the designed Max-E47 protein chimera behaves both structurally and functionally like its native counterparts

Quenching and enhancement effects of various disinfectant chemistries on Sciegiene luminometer readings, the control was ATP standard solution with 10⁻⁷ molarity.

<p>Quenching and enhancement effects of various disinfectant chemistries on Sciegiene luminometer readings, the control was ATP standard solution with 10⁻⁷ molarity.</p

Quenching and enhancement effects of various disinfectant chemistries on Kikkoman luminometer readings, the control was ATP standard solution with 10⁻⁷ molarity.

<p>Quenching and enhancement effects of various disinfectant chemistries on Kikkoman luminometer readings, the control was ATP standard solution with 10⁻⁷ molarity.</p

Quenching and enhancement effects of various disinfectant chemistries on 3M luminometer readings. the control was ATP standard solution with 10⁻⁸ molarity.

<p>Quenching and enhancement effects of various disinfectant chemistries on 3M luminometer readings. the control was ATP standard solution with 10⁻⁸ molarity.</p

Tested disinfectants, their active ingredients, and manufacturers.

<p>Tested disinfectants, their active ingredients, and manufacturers.</p

The minimum CFU of <i>S. aureus</i> that was detected for each ATP meter.

<p>The minimum CFU of <i>S. aureus</i> that was detected for each ATP meter.</p

Geometric mean of ATP readings for various dilutions of <i>S. aureus</i> CFUs.

<p>Geometric mean of ATP readings for various dilutions of <i>S. aureus</i> CFUs.</p

Correlation between ATP amount and ATP reading values in logarithmic scales for 4 different ATP meters.

<p>Correlation between ATP amount and ATP reading values in logarithmic scales for 4 different ATP meters.</p

The Effect of Lipopolysaccharide on Ischemic-Reperfusion Injury of Heart: A Double Hit Model of Myocardial Ischemia and Endotoxemia

Introduction: Myocardial ischemia may coincide and interact with sepsis and inflammation. Our objective was to examine the effects of bacterial endotoxin on myocardial functions and cell injury during acute ischemia. Methods: Rabbits were pretreated with incremental doses of E. Coli lipopolysaccharide (LPS) or normal saline. Myocardial ischemia was induced by 50-minute occlusion of left anterior descending artery. S-TNFaR was additionally used to block the effects LPS. Results: Ventricular contractility as it was measured by dp/dt during systole decreased from 2445±1298 to 1422±944 mmHg/s, P​=.019. Isovolumetric relaxation time as an index of diastolic function was prolonged from 50±18 ms to 102±64 ms following ischemia. Pretreatment with low concentrations of LPS (<1 µg) had no effect on dp/dt, while at higher concentrations it suppressed both contractility and prolonged IVRT. Cell injury as measured by cardiac troponin I level increased to 15.1±3.2 ng/dL following ischemia and continued to rise with higher doses of LPS. While blocking TNFa did not improve the myocardial contractility after ischemia, it eliminated additional deleterious effects of LPS. Conclusion: Lower doses of LPS had no deleterious effect on myocardial function, whereas higher doses of this endotoxin cause cardiac dysfunction and increased extent of injury

Data collection and refinement statistics.

a<p>Data in the highest resolution shell are shown in parentheses.</p