Mononuclear copper(II) and nickel(II) complexes, [(C5H6N2)Cu(IDA)(H2O)] (1) and (C5H7N2)2[Ni(IDA)2(H2O)] (2) [H2IDA = iminodiacetic acid; C5H6N2 = 4-aminopyridine; C5H7N2 = protonated 2-aminopyridine], have been synthesized, and their crystal structures were solved using single crystal X-ray diffraction data. A detailed analysis of Hirshfeld surfaces and fingerprint plots facilitates a comparison of intermolecular interactions, which are crucial in building different supramolecular architectures. Molecules are linked by a combination of N–H···O, O–H···O and C–H···O hydrogen bonds into two-dimensional framework, whose formation is readily analyzed in terms of substructures of lower dimensionality with zero finite zero-dimensional dimeric units as the building blocks within the structures. Moreover, the aromatic molecules that are engaged in lone pair···π interactions with the noncoordinated carbonyl moieties play a crucial role in stabilizing the self-assembly process observed for both complexes. Intricate combinations of hydrogen bonding, lone pair···π and π–π interactions are fully described along with the computational studies.

Diproline segments have been advanced as templates for nucleation of folded structure in designed peptides. The conformational space available to homochiral and heterochiral diproline segments has been probed by crystallographic and NMR studies on model peptides containing L-Pro-L-Pro and D-Pro-L-Pro units. Four distinct classes of model peptides have been investigated: a) isolated D-Pro-L-Pro segments which form type II' beta-turn; b) D-Pro-L-Pro-L-Xxx sequences which form type II'-I (betaII'-I, consecutive beta-turns) turns; c) D-Pro-L-Pro-D-Xxx sequences; d) L-Pro-L-Pro-L-Xxx sequences. A total of 17 peptide crystal structures containing diproline segments are reported. Peptides of the type Piv-D-Pro-L-Pro-L-Xxx-NHMe are conformationally homogeneous, adopting consecutive beta-turn conformations. Peptides in the series Piv-D-Pro-L-Pro-D-Xxx-NHMe and Piv-L-Pro-L-Pro-L-Xxx-NHMe, display a heterogeneity of structures in crystals. A type VIa beta-turn conformation is characterized in Piv-L-Pro-L-Pro-L-Phe-OMe (18), while an example of a 5-->1 hydrogen bonded alpha-turn is observed in crystals of Piv-D-Pro-L-Pro-D-Ala-NHMe (11). An analysis of pyrrolidine conformations suggests a preferred proline puckering geometry is favored only in the case of heterochiral diproline segments. Solution NMR studies, reveal a strong conformational influence of the C-terminal Xxx residues on the structures of diproline segments. In L-Pro-L-Pro-L-Xxx sequences, the Xxx residues strongly determine the population of Pro-Pro cis conformers, with an overwhelming population of the trans form in L-Xxx=L-Ala (19).

A one-dimensional water wire has been characterized by X-ray diffraction in single crystals of the tripeptide Ac-Phe-Pro-Trp-OMe. Crystals in the hexagonal space group P6(5) reveal a central hydrophobic channel lined by aromatic residues which entraps an approximately linear array of hydrogen bonded water molecules. The absence of any significant van der Waals contact with the channel walls suggests that the dominant interaction between the "water wire" and "peptide nanotube" is electrostatic in origin. An energy difference of 16 kJ mol(-1) is estimated for the distinct orientations of the water wire dipole with respect to the macrodipole of the peptide nanotube. The structural model suggests that Grotthuss type proton conduction may, through constricted hydrophobic channels, be facilitated by concerted, rotational reorientation of water molecules.

Background: Heart disease is the leading cause of tobacco‐related death in smokers and of deaths due to secondhand smoke (SHS) exposure in nonsmokers. This study centers on the development and evaluation of an evidence‐based model curriculum for improving clinical attention to tobacco use and SHS exposure in cardiology. Hypothesis: We hypothesized that the curriculum would be associated with improvements in clinician tobacco‐related knowledge, attitudes, confidence, and counseling behaviors from pre‐to post‐training and at the 3‐month follow‐up. Methods: The 1‐hour Cardiology Rx for Change curriculum was evaluated with 22 cardiology fellows and 77 medical residents with consistent training effects observed between the 2 groups. Results: Trainees' tobacco treatment knowledge increased significantly from pre‐ to post‐training (t[81] = 6.51, P<0.001), and perceived barriers to providing cessation treatment decreased significantly (t[81] = −3.97, P<0.001). The changes, however, were not sustained at the 3‐month follow‐up, suggesting the need for booster training efforts. From pretraining to 3‐month follow‐up, the training was associated with significant sustained gains in clinician confidence for treating tobacco dependence (t[61] = 3.69, P = 0.001) and with improvements in clinicians assessing patients' readiness to quit smoking (from 61% to 79%, t[59] = 3.69,P<0.001) and providing assistance with quitting (from 47% to 59%, t[59] = 2.12, P = 0.038). Asking patients about tobacco use, advising cessation, and arranging follow‐up also increased over time, but not significantly. All participants (100%) recommended the curriculum for dissemination to other training programs. Conclusions: Available online via http://rxforchange.ucsf.edu, Cardiology Rx for Change offers a packaged training tool for improving treatment of tobacco use and SHS exposure in cardiology care. © 2011 Wiley Periodicals, Inc. This work was supported by the Flight Attendant Medical Research Institute (FAMRI) William Cahan Distinguished Professor Award (PI: W. Grossman), and the State of California Tobacco‐Related Disease Research Program (# 17RT‐0077, PI: J.J. Prochaska). The authors have no other funding, financial relationships, or conflicts of interest to disclose.

The covalent linkage between the side-chain and the backbone nitrogen atom of proline leads to the formation of the five-membered pyrrolidine ring and hence restriction of the backbone torsional angle ϕ to values of -60 °± 30° for the L-proline. Diproline segments constitute a chain fragment with considerably reduced conformational choices. In the current study, the conformational states for the diproline segment (( L) Pro-( L) Pro) found in proteins has been investigated with an emphasis on the cis and trans states for the Pro-Pro peptide bond. The occurrence of diproline segments in turns and other secondary structures has been studied and compared to that of Xaa-Pro-Yaa segments in proteins which gives us a better understanding on the restriction imposed on other residues by the diproline segment and the single proline residue. The study indicates that P(II) -P(II) and P(II) -α are the most favorable conformational states for the diproline segment. The analysis on Xaa-Pro-Yaa sequences reveals that the Xaa-Pro peptide bond exists preferably as the trans conformer rather than the cis conformer. The present study may lead to a better understanding of the behavior of proline occurring in diproline segments which can facilitate various designed diproline-based synthetic templates for biological and structural studies.