Lessons,narratives, and research directions for a sustainable circular economy

The current enthusiasm for the circular economy (CE) offers a unique opportunity to advance the impact of research on sustainability transitions. Diverse interpretations of CE by scholars, however, produce partly opposing assessments of its potential benefits, which can hinder progress. Here, we synthesize policy-relevant lessons and research directions for a sustainable CE and identify three narratives—optimist, reformist, and skeptical—that underpin the ambiguity in CE assessments. Based on 54 key CE scholars’ insights, we identify three research needs: the articulation and discussion of ontologically distinct CE narratives; bridging of technical, managerial, socio-economic, environmental, and political CE perspectives; and critical assessment of opportunities and limits of CE science–policy interactions. Our findings offer practical guidance for scholars to engage reflexively with the rapid expansion of CE knowledge, identify and pursue high-impact research directions, and communicate more effectively with practitioners and policymakers.     

Crystallographic Studies on α- and β-D-glucopyranosyl Formamide Analogues,Inhibitors of Glycogen Phosphorylase

Abstract

The catalytic site of glycogen phosphorylase (GP) is currently under investigation as a target for inhibition of hepatic glycogenolysis under high glucose conditions. Three D-glucopyranosyl analogues, C-(1-azido-α-D-glucopyranosyl) formamide, C-(1-acetamido-α-D-glucopyranosyl) formamide, and C-(1-hydroxy-β-D-glucopyranosyl) formamide, were recognised as moderate competitive inhibitors of muscle glycogen phosphorylase b (GPb) [with respect to α-D-glucose 1-phosphate (Glc-1-P)] with K_i values of 1.80 (±0.2) mM, 0.31 (±0.01) mM, and 0.88 (±0.04) mM, respectively. In order to elucidate the structural basis of inhibition, we determined the structure of muscle GPb complexed with the three compounds at 2.1, 2.06 and 2.0 Å resolution, respectively. The complex structures revealed that the inhibitors can be accommodated in the catalytic site of T-state GPb with very little change of the tertiary structure, and provide a rationalisation for understanding potency of the inhibitors. The glucopyranose moiety makes the standard hydrogen bonds and van der Waals contacts as observed in the GPb-glucose complex, while the substituent groups in the α- and β-position of the C1 atom make additional hydrogen bonding and van der Walls interactions to the protein.