Glycine porphyrins from

ALA and PBG are the precursors of porphyrin synthesis (Fig. 7.3.1). ALA is synthesized from glycine and succinyl-coenzyme A by ALAS. Two molecules of ALA are converted to PBG by the enzyme ALAD. 

Many important biomolecules are derived from amino acids. Glycine is a precursor of porphyrins. Degradation of iron-porphyrin (heme) generates bilirubin, which is converted to bile pigments, with several physiological functions. 

By degradation of 14C-labeled porphyrins formed from labeled acetate and glycine molecules, Shemin and Rittenberg established the labeling pattern for the... 

Many biologically important routes of amino acid utilization, other than those leading to incorporation into proteins, are known. Some of these routes are distinctly anabolic pathways in which the amino acids serve as an initial substrate in an independent biosynthetic pathway. Other simple pathways involve the conversion of one amino acid to another, such as the formation of tyrosine from phenylalanine. The utilization of glycine in the formation of porphyrin derivatives occurs by very complex highly branched pathways. Some other biologically important pathways lead to the biosynthesis of small peptides as in the biosynthesis of glutathione. 

Mammalian Porphyrins Are Synthesized from Glycine and Succinyl Coenzyme A... 

The growth, porphyrin excretion, and the activity of the first three enzymes involved in the synthesis of tetrapyrrole skeleton from glycine and succinyl-CoA, ALA synthase, PBG synthase, and PBG deminase, were measured under excretion (ethanol/malate/glutamate, 40°C) and non-excretion (ethanol/NaHC03/NH4Cl, 40°C) conditions (Figures 2 and 3). 

Heme is produced from glycine and succinyl CoA via a series of porphyrins. 

Hgb consists of a protein component with two a and two p chains each chain is linked to a heme group consisting of a porphyrin ring structure with an iron atom chelated at its center, which is capable of binding oxygen. The initial step in the synthesis of heme from the substrate succinyl CoA and glycine requires the presence of pyridox-ine phosphate (vitamin Be) as a catalyst. Following its synthesis in the cytoplasmic mitochondria of the RBC, heme diffuses into the extra-mitochondrial space, combines with the completed a and p chains, and forms Hgb. 

Heme is an iron- and nitrogen-containing porphyrin ring system synthesized from glycine and succinyl-CoA. Protoporphyrin IX, the precursor of heme, is also a precursor of the chlorophylls. 

---