 2 H = ( 2 H / 1 H) Sample vs. ( 2 H / 1 H) Reference 13 C/ 12 C – 15 N/ 14 N – 18 O/ 16 O – 34 S/ 32 S – 37 Cl/ 35 Cl – 81 Br/ 79 Br

Malin Söderman Junior Research Engineer

We develop methods – Visitors come and use them Self-cost model We are available for -General isotope advice (planning) - Collaboration - One-off - Short term - Long term - Proposal assist

… Equilibrium Isotope Effects (EIE) – isotopic phase partitioning … Kinetic Isotope Effects (KIE) – isotopic reaction rates Zero-point energies…  =(1/2+n)h    (  /m) ½ Vibrational frequency Isotope mass Force constant

Heavy isotopes favour a strong bond The Equilibrium Isotope Effect ( 2 H / 1 H) Phase X-H* ( 2 H / 1 H) Phase Y-H* EIE = solventanalyte

The Kinetic Isotope Effect k rate =Ae -Ea/RT Free energy Reaction coordinate E a Light E E a Heavy E KIE = k Light / k Heavy

…KIE = k Light / k Heavy Holmstrand et al., Chemosphere 69 (2007) 1533–1539 DDT DDE

KIEs of 3 photochemical reactions  13 C  15 N 2H2H Hartenbach et al, Environ. Sci. Technol. 2008, 42, 7751–7756 Isotope composition Atrazine Concentration

R(+) or S(-) Catalysis by DL-2-haloacid dehalogenase for stereo isomers as determined from Kinetic Isotope Effects (KIEs) Papajak et al., Biochemistry 2006, 45,

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)

? ? Chemistry Labeling Reaction mechanisms Reaction monitoring Reaction identification Linking source & product Environmental sciences Ecology Plant physiology Microbiology Biochemistry

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