An Equilibrium Isotope Effect Molecular oxygen adducts in metalloenzymes – side-on or end-on? Side-on End-on
The characterization of intermediates in oxidation reactions of transition metals – Metalloenzymes Side-on End-on The derived oxygen isotopic effects have been used to (i) differentiate inner-sphere from outer-sphere electron transfer (ii) identify metal-O2 intermediates (iii) assess mechanisms of O-O bond-breaking/making reactions Ashley, Brinkley and Roth, Oxygen Isotope Effects as Structural and Mechanistic Probes in Inorganic Oxidation Chemistry, Inorg. Chem. 2010, 49, 3661–3675
“No deuterium was incorporated… the active site of the enzyme is probably in a closed conformation during catalysis” Hydrogen exchange labeling to study a reaction mechnism - choice of labels and analytical technique 2 H label Natural 2 H level Guangqi et al., Biochimie 92 (2010) 1454e1457 Tracers and labels: - Is natural abundance enough? (safety, cost, feasibility) - Can KIE or EIE help? (additional information) - Added value of IRMS instruments? (trace weaker signals)
Macronutrient sourcing for biosynthesis using 13 C analysis of amino acids – direct routing from diet to tissue Filled = dietOpen = collagen Diet composition DietProteinEnergy D2AC3C3 C3C3 D3GC3C3 C4C4 D4HC4C4 C4C4 D5IC4C4 C3C3 Jim et al., British Journal of Nutrition (2006), 95, 1055–1062 C3C3 C4C4 -25‰ -12‰ C 3 plants = - 25‰ (e.g. rice) C 4 plants = - 12‰ (maize)
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