Otto Schultzen
With Marceli Nencki ( 1847–1901 ) he performed physiological studies of urea , discovering that amino acids ( glycine and leucine ) are intermediate links between protein and urea . , With Bernhard Naunyn ( 1839–1925 ) he conducted important research involving the behavior of benzene-derived hydrocarbons in the body . 
<triplet> glycine <subj> amino acids <obj> instance of <triplet> protein <subj> amino acids <obj> has part