Iron-Containing Ureases.

Conventional ureases possess dinuclear nickel active sites that are oxygen-stable and require a set of accessory proteins for metallocenter biosynthesis. By contrast, oxygen-labile ureases have active sites containing dual ferrous ions and lack a requirement for maturation proteins. The structures of the two types of urease are remarkably similar, with an active site architecture that includes two imidazoles and a carboxylate ligand coordinated to one metal, two imidazoles coordinated to the second metal, and a metal-bridging carbamylated lysine ligand.

Fasting and fasting-mimicking treatment activate SIRT1/LXRα and alleviate diabetes-induced systemic and microvascular dysfunction.

Aims/hypothesis: Homo sapiens evolved under conditions of intermittent food availability and prolonged fasting between meals. Periods of fasting are important for recovery from meal-induced oxidative and metabolic stress, and tissue repair. Constant high energy-density food availability in present-day society contributes to the pathogenesis of chronic diseases, including diabetes and its complications, with intermittent fasting (IF) and energy restriction shown to improve metabolic health.

Assessment of the Maximal Activity of Complex IV in the Inner Mitochondrial Membrane by Tandem Electrochemistry and Respirometry.

Assessment of activities of mitochondrial electron transport enzymes is important for understanding mechanisms of metabolic diseases, but structural organization of mitochondria and low sample availability pose distinctive challenges for in situ functional studies. We report the development of a tandem microfluidic respirometer that simultaneously tracks both the reduction of mediators on the electrode and the ensuing reduction of O by complex IV in the inner mitochondrial membrane. The response time of O consumption to multiple alternating potential steps is of approximately 10 s for a 150 μm-thick sample.

Mitochondrial Ceramide Effects on the Retinal Pigment Epithelium in Diabetes.

Mitochondrial damage in the cells comprising inner (retinal endothelial cells) and outer (retinal pigment epithelium (RPE)) blood-retinal barriers (BRB) is known to precede the initial BRB breakdown and further histopathological abnormalities in diabetic retinopathy (DR). We previously demonstrated that activation of acid sphingomyelinase (ASM) is an important early event in the pathogenesis of DR, and recent studies have demonstrated that there is an intricate connection between ceramide and mitochondrial function. This study aimed to determine the role of ASM-dependent mitochondrial ceramide accumulation in diabetes-induced RPE cell damage.

Structural Origin of the Large Redox-Linked Reorganization in the 2-Oxoglutarate Dependent Oxygenase, TauD.

2-Oxoglutarate (2OG)-dependent oxygenases catalyze a wide range of chemical transformations via C-H bond activation. Prior studies raised the question of whether substrate hydroxylation by these enzymes occurs via a hydroxyl rebound or alkoxide mechanism and highlighted the need to understand the thermodynamic properties of transient intermediates. A recent spectroelectrochemical investigation of the 2OG-dependent oxygenase, taurine hydroxylase (TauD), revealed a strong link between the redox potential of the Fe(II)/Fe(III) couple and conformational changes of the enzyme.