We propose that arginine side chains often play a previously unappreciated general structural role in the maintenance of tertiary structure in proteins, wherein the positively charged guanidinium group forms multiple hydrogen bonds to backbone carbonyl oxygens. Using as a criterion for a "structural" arginine one that forms 4 or more hydrogen bonds to 3 or more backbone carbonyl oxygens, we have used molecular graphics to locate arginines of interest in 4 proteins: Arg 180 in Thermus thermophilus manganese superoxide dismutase, Arg 254 in human carbonic anhydrase 11, Arg 31 in Streptomyces rubiginosusxylose isomerase, and Arg 313 in Rhodospirillum rubrum ribulose-l,S-bisphosphate carboxylase/oxygenase. Arg 180 helps to mold the active site channel of superoxide dismutase, whereas in each of the other enzymes the structural arginine is buried in the "mantle" (i.e., inside, but near the surface) of the protein interior well removed from the active site, where it makes 5 hydrogen bonds to 4 backbone carbonyl oxygens. Using a more relaxed criterion of 3 or more hydrogen bonds to 2 or more backbone carbonyl oxygens, arginines that play a potentially important structural role were found in yeast enolase, Bacillus stearothermophilus glyceraldehyde-3-phosphate dehydrogenase, bacteriophage T4 and human lysozymes, Enteromorpha prolifera plastocyanin, HIV-1 protease, Trypanosoma brucei brucei and yeast triosephosphate isomerases, and Escherichia coli trp aporepressor (but not trp repressor or the trp repressor/operator complex). In addition to helping form the active site funnel in superoxide dismutase, the structural arginines found in this study play such diverse roles as stapling together 3 strands of backbone from different regions of the primary sequence, and tying a-helix to a-helix, &turn to 6-turn, and subunit to subunit.Keywords: backbone carbonyl oxygens; buried arginine; carbonic anhydrase; enolase; glyceraldehyde-3-phosphate dehydrogenase; HIV-1 protease; lysozyme; manganese superoxide dismutase; multiple hydrogen bonds; plastocyanin; ribulose-l,5-bisphosphate carboxylase/oxygenase; structural arginine; triosephosphate isomerase; trp aporepressor; xylose isomeraseThe guanidinium group of arginine is the most polar of all the common amino acid side chains found in proteins (Wolfenden, 1983) and is thus the residue most likely to be found on the surface in an aqueous environment. The side chain almost always has a pK, 112 and the positively charged planar guanidinium group can be a hydrogen donor in the formation of up to 5 hydrogen bonds (Fig. 1). Arginine plays a major role in the binding of negatively charged substrates, cofactors, and effectors to

Self-compassion has shown promise as an adaptive resource for coping with uncertainties and challenges. This study examined the relationship between self-compassion and professional wellbeing (work engagement, exhaustion, and professional life satisfaction) of physicians, who frequently face uncertainties and challenges in their clinical practice. Fifty-seven practicing physicians in Canada participated in the study. Overall, 65% of the participants were female; 47% were in the early-career stage; 49% were family medicine (FM) physicians, with the rest being non-FM specialists. It was hypothesized that (a) self-compassionate physicians would experience greater work engagement and less exhaustion from work than physicians reporting lower self-compassion and (b) self-compassionate physicians would experience greater professional life satisfaction through their greater work engagement and less exhaustion than physicians reporting lower self-compassion. Sequential regression analyses were performed. The results confirmed the hypothesized associations, indicating that self-compassionate physicians experienced more positive work engagement, felt less emotionally, physically, and cognitively exhausted due to work demands, and were more satisfied with their professional life than physicians who exhibited less compassion toward themselves in uncertain and challenging times. Future studies are needed to determine optimal ways to support practicing physicians and medical trainees in becoming more self-compassionate for their enhanced wellbeing and, ultimately, for the provision of effective patient care.

Context Continuity of supervision (CoS) is generally accepted as an important element of competency‐based medical education (CBME). However, collecting and interpreting evidence for its effectiveness are a challenge because we lack a shared understanding of CoS. Translating the available evidence about CoS into practice is an even greater challenge because the evidence largely exists in the undergraduate medical education (UME) literature, whereas literature about CBME is mostly situated in postgraduate medical education (PGME). Proposal We explore the potential dangers of basing assumptions of the importance of CoS in CBME on evidence from the UME level where CBME is yet to be widely implemented. First, we discuss current understandings of what is meant by CoS and examine some of its evidence and where such evidence comes from. Next, we consider relevant theories related to CoS in the context of CBME and review how it is conceptualised in different educational models. We then discuss some contextual and pedagogical differences between UME and PGME when CoS is considered. Finally, we propose a shared understanding of CoS and outline implications and next steps to determine if the benefits of CoS seen at the UME level will also manifest with PGME learners. Conclusions We have the opportunity to undertake research to close our gap in knowledge about CoS at the PGME level using data emerging from our experiences with CBME. Selecting specific dimensions of CoS will allow research that is necessary to determine that what works at the UME level will also work at the PGME level as we continue to march towards CBME.

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