17 Amino acids are precursors of many specialized biomolecules Radioisotope tracer experiments showed that the porphyrin(卟啉) ring of the heme groups in mammals are made from 8 Gly and 8 succinyl-CoA (Glu in plants and bacteria) Deficiency of enzymes leading to heme biosynthesis cause diseases called porphyrias (The degradation of heme yields bilirubin, a linear tetrapyrrole derivative, and the typical pigments found in bile, urine, and feces, a deficiency of which will cause jaundice,黄疸)17. Amino acids are precursors of many specialized biomolecules • Radioisotope tracer experiments showed that the porphyrin (卟啉)ring of the heme groups in mammals are made from 8 Gly and 8 succinyl-CoA (Glu in plants and bacteria). • Deficiency of enzymes leading to heme biosynthesis cause diseases called porphyrias. • (The degradation of heme yields bilirubin, a linear tetrapyrrole derivative, and the typical pigments found in bile, urine, and feces, a deficiency of which will cause jaundice，黄疸)