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2H = (2H / 1H)Sample vs. (2H / 1H)Reference
13C/12C – 15N/14N – 18O/16O – 34S/32S – 37Cl/35Cl – 81Br/79Br
Malin SödermanJunior 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
(2H / 1H)Phase X-H*
(2H / 1H)Phase Y-H*
EIE =
solvent analyte
The Kinetic Isotope Effect
krate=Ae-Ea/RT
Fre
e en
ergy
Reaction coordinate
Ea LightEEa HeavyE
KIE = kLight / kHeavy
…KIE = kLight / kHeavy
Holmstrand et al., Chemosphere 69 (2007) 1533–1539
DDT DDE
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, 6012-6017
An Equilibrium Isotope EffectMolecular oxygen adducts in metalloenzymes
– side-on or end-on?
Side-on
End-on
The characterization of intermediates
in oxidation reactions of transition metals – MetalloenzymesSide-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 studya reaction mechnism
- choice of labels and analytical technique
2H label
Natural 2H 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 13C analysis of amino acids
– direct routing from diet to tissue
Filled = diet Open = collagen
Diet compositionDiet Protein EnergyD2A C3 C3
D3G C3 C4
D4H C4 C4
D5I C4 C3
Jim et al., British Journal of Nutrition (2006), 95, 1055–1062
C3
C4
-25‰
-12‰
C3 plants = - 25‰ (e.g. rice)C4 plants = - 12‰ (maize)
?
Chemistry
Labeling
Reactionmechanisms
Reactionmonitoring
Reactionidentification
Linking source &product
Environmentalsciences
Ecology
Plant physiology
Microbiology
Biochemistry
E-mail: [email protected]
Cell phone: 070 760 7229
Website: http://delta.geo.su.se…where you will find this presentation…