Isotopes, uses distribution studies

Now let us summarize our experimental results. For obvious reasons of simpler detection, we have studied the isotopic variant of reaction (1) OH + D2. In Fig. 4 we report the laboratory angular distributions of the HOD product at Eq = 26.4 kJ/mol and of the CO2 product at Ec= 59.0 kJ/mol, together with the corresponding most probable Newton diagrams. The lab angle 0 is measured from the OH beam. In the c.m. coordinate system, d = 0 is the direction of the OH beam and represents the forward direction with respect to OH. 

Recent mechanism studies involving incubations with stable isotopes (66,69,70) and studies by us on conformiational analysis (38-42), distribution (7), structure-function/metabolism relationships (54, 55) and mechanistic enzymology of sterol transformation (12,56), negate the otherwise attractive explanation hypothesized by Ourisson et al, (9,10) for evolution of the sterol pathway beginning with the cycloartenol-based pathway. The new data indicate that the lanosterol-based pathway may have evolved before cycloartenol-based pathway, the squalene-oxide cyclase and... 

---