Positron emission tomography imaging was carried out in Sprague Dawley rats (five control

and five streptozotocin-induced diabetic) and BioBreeding diabetes-prone rats (three at 7 weeks and three at 12 weeks) using the high-resolution research tomograph (HRRT) after 0.187 +/- 0.084 mCi [F-18]Ex(9-39) administration. Time activity curves were obtained from pancreas, liver and kidney. Pancreases were assayed for insulin content after the imaging study.

Results: Site-specifically labeled [F-18]Ex(9-39) was purified on a G15 open column with radiochemical and chemical purities >98%. Positron 4-Hydroxytamoxifen datasheet emission tomography imaging showed pancreatic standardized uptake value (SUV) peaked at 10 min and plateaued by 50 min to the end of scan (240 min). No correlations of pancreatic SUV with postmortem measures of insulin content were seen.

Conclusions: [F-18]Ex(9-39) was successfully prepared and used for PET imaging for the first time to measure pancreatic BCM. The results suggest that derivatization of the Lys27 residue might reduce binding affinity, as evidenced by the absence of specific binding. Exendin analogues radiolabeled at other sites may elucidate the active site required for binding. (C) 2012 Elsevier Inc. All rights reserved.”
“Although 8-anilinonaphthalene-1-sulfonic

acid (ANS) is frequently used in protein folding studies, the structural and thermodynamic effects of its binding to proteins are not well understood. Using high-resolution 4SC-202 two-dimensional NMR and human interleukin-1 receptor antagonist (IL-1ra) as a model protein, we obtained detailed information on ANS-protein interactions in the absence and presence of

urea. The effects of ambient to elevated temperatures on the affinity and specificity of ANS binding were assessed from experiments performed at 25 degrees C find more and 37 degrees C. Overall, the affinity of ANS was lower at 37 degrees C compared to 25 degrees C, but no significant change in the site specificity of binding was observed from the chemical shift perturbation data. The same site-specific binding was evident in the presence of 5.2 M urea, well within the unfolding transition region, and resulted in selective stabilization of the folded state. Based on the two-state denaturation mechanism, ANS-dependent changes in the protein stability were estimated from relative intensities of two amide resonances specific to the folded and unfolded states of IL-1ra. No evidence was found for any ANS-induced partially denatured or aggregated forms of IL-1ra throughout the experimental conditions, consistent with a cooperative and reversible denaturation process. The NMR results support earlier observations on the tendency of ANS to interact with solvent-exposed positively charged sites on proteins.