General Applications in Biochemistry

The relative ease of synthesis of tritiated sugars, as compared with that of 14C-labeled sugars, has led to the increasing use of tritiated substrates in the determination of the molecular course of a particular biological transformation. These studies, although limited 

Inositol is formed from D-glucose 6-phosphate by direct cyclization of the chain. D-Glucose 6-phosphate was also shown to be a precursor of deoxyinositols in leaf tissues, as D-glucose-6-t 6-phosphate (72) was converted193 into quercitol-2-t (l-2,3,5/1,4) (73) and194 viburnitol-4-t (l-1,2,4/3,5) (74). Labeling in the precursor and the products corresponded to a direct cyclization-mechanism. 

Loss of tritium from D-glucose-3-t (but not from D-glucose-J-f) during the biosynthesis of L-streptidine (77), which is a component of the antibiotic streptomycin, showed that the 3-guanidination of D-l-deoxy-l-guanidino-sci/Wo-inositol (75) may proceed through the 3-ketone intermediate 76. The enzyme system was specific195 for the D-isomer (75). 

Hydrogen Movement within the Cell, and Incorporation into Cell Components 

In addition to providing information concerning hydrogen movements during a particular enzyme reaction, hydrogen isotopes have 

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