Glycine glutathione synthesis

This is followed by removal of the glutamic acid and the glycine residues, which is followed by acetylation of the remaining cysteine. Essential amino acids are required for the synthesis of the proteins involved, pantothenic acid for coenzyme A synthesis, and phosphorus for synthesis of the ATP needed for glutathione synthesis. Similar scenarios can be developed for glucuronide and sulfate formation, acetylation, and other phase II reaction systems. 

Fig. 37.6. 7-Glutamyl cycle. In cells of the intestine and kidney, amino acids can be trans-pwrted across the cell membrane by reacting with glutathione (7-glutamyl-cysteinyl-glycine) to form a 7-glutamyl amino acid. The amino acid is released into the cell, and glutathione is resynthesized. However, the major role of this cycle is glutathione synthesis, and many tissues lack the transpieptidase and 5-oxo-prohnase activities.

The sulfur-containing amino acids, cysteine and methionine, are essential components of proteins and also participate in special reactions. In animals methionine is of particular importance because of its role in the transfer of methyl groups. Cysteine is a component of glutathione, 7-glutamyl-cysteinyl-glycine. The synthesis of these important amino acids occurs in plants and microorganisms by as yet undefined pathways. Certain interconversions at the amino acid level have been studied in animals, and some of the enzymes concerned have been identified. More is known about the degradation of the amino acids. 

Glutathione synthesis from glutamylcysteine, as measured by the incorporation of C -glycine into the tripeptide, is accompanied by the release of an equimolar amount of Pi from ATP. The release of P<,... 

Fig. 9. Proposed pathways for the synthesis and catabolism of glutathione (y-glutamylcysteinyl-glycine) i n plants. The enzymes involved in glutathione synthesis are (1) >.glutamylcysteine synthetase and (2) glutathione synthetase. The enzymes involved in glutathione catabolism are (3) glutathione carboxypeptidase, (4) yglutamylcyclotransferase, and (5) 5-oxoprolinase. (After Rennen-beig, 1987.)...

Protein synthesis Glycogen synthesis Lactate uptake Amino acid uptake Glutaminase Glycine oxidation Ketoisocaproate oxidation Acetyl-CoA carboxylase Urea synthesis from amino acids Glutathione (GSH) efflux Taurocholate excretion into bile Actin polymerization Microtubule stability Lysosomal pH... 

A-30. Glycine is involved in the synthesis of haemoglobin, creatine phosphate, purines, glutathione, proteins, phospholipids, bile acids and detoxification reactions. 

Glutathione synthetase (EC 6.3.2.3 GSH-S) mediates the second step in the synthesis of GSH, by the addition of glycine to the dipeptide y-glutamylcysteine. The protein is a homodiraer of 52kDa. ... 

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