Shemin, David

How the division of spoils came about I do not recall—it may have been by drawing lots. At any rate, David Shemin drew amino acid metabolism, which led to his classical work on heme biosynthesis. David Rittenburg was to continue his interest in protein synthesis and turnover, and lipids were to be my territory. 

Early isotope tracer experiments by David Shemin permitted the elucidation of the formation of the immediate precursor of the porphyrin needed for the cytochromes and for hemoglobin. These studies indicated that the glycine methylene carbon and nitrogen were incorporated along with both carbons of acetate. Subsequent enzymatic studies in both bacteria and animals revealed a condensation reaction between succinyl-CoA and glycine to yield 5-amino-levulinate and C02 (presumably by way of an enzyme-bound /3-keto acid, a-amino-/3-ketoadipate) (fig. 22.13). 

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