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Abstract β‐lactams are a chemically diverse group of molecules with a wide range of biological activities. Having recently observed curious trends in²J_HHcoupling values in studies on this structural class, we sought to obtain a more comprehensive understanding of these diagnostic NMR parameters, specifically interrogating¹J_CH,²J_CH, and²J_HH, to differentiate 3‐ and 4‐monosubstituted β‐lactams. Further investigation using computational chemistry methods was employed to explore the geometric and electronic origins for the observed and calculated differences between the two substitution patterns. 

Metabolic suppression is a hallmark of animal dormancy that promotes overall energy savings. Some diapausing insects and some mammalian hibernators have regular cyclic patterns of substantial metabolic depression alternating with periodic arousal where metabolic rates increase dramatically. Previous studies, largely in mammalian hibernators, have shown that periodic arousal is driven by an increase in aerobic mitochondrial metabolism and that many molecules related to energy metabolism fluctuate predictably across periodic arousal cycles. However, it is still not clear how these rapid metabolic shifts are regulated. We first found that diapausing flesh fly pupae primarily use anaerobic glycolysis during metabolic depression but engage in aerobic respiration through the tricarboxylic acid cycle during periodic arousal. Diapausing pupae also clear anaerobic by-products and regenerate many metabolic intermediates depleted in metabolic depression during arousal, consistent with patterns in mammalian hibernators. We found that decreased levels of reactive oxygen species (ROS) induced metabolic arousal and elevated ROS extended the duration of metabolic depression. Our data suggest ROS regulates the timing of metabolic arousal by changing the activity of two critical metabolic enzymes, pyruvate dehydrogenase and carnitine palmitoyltransferase I by modulating the levels of hypoxia inducible transcription factor (HIF) and phosphorylation of adenosine 5′-monophosphate-activated protein kinase (AMPK). Our study shows that ROS signaling regulates periodic arousal in our insect diapasue system, suggesting the possible importance ROS for regulating other types of of metabolic cycles in dormancy as well.