Phenylalanine racemase (ATP-hydrolysing)

 The enzyme phenylalanine racemase (EC 5.1.1.11, phenylalanine racemase, phenylalanine racemase (adenosine triphosphate-hydrolysing), gramicidin S synthetase I) is the enzyme that acts on amino acids and derivatives. It activates both the L & D stereo isomers of phenylalanine to form L-phenylalanyl adenylate and D-phenylalanyl adenylate, which are bound to the enzyme. These bound compounds are then transferred to the thiol group of the enzyme followed by conversion of its configuration, the D-isomer being the more favorable configuration of the two, with a 7 to 3 ratio between the two isomers. The racemisation reaction of phenylalanine is coupled with the highly favorable hydrolysis of adenosine triphosphate (ATP) to adenosine monophosphate (AMP) and pyrophosphate (PP), thermodynamically allowing it to proceed. This reaction is then drawn forward by further hydrolyzing PP to inorganic phosphate (Pi), via Le Chatelier's principle.

Phenylalanine racemase (ATP-hydrolysing)
1amu.png
Phenylalanine Racemase(ATP Hydrolysing), image from Protein Data Bank
Identifiers
EC number5.1.1.11
CAS number37290-95-2
Databases
IntEnzIntEnz view
BRENDABRENDA entry
ExPASyNiceZyme view
KEGGKEGG entry
MetaCycmetabolic pathway
PRIAMprofile
PDB structuresRCSB PDB PDBe PDBsum

Other namesEdit

  • phenylalanine racemase
  • phenylalanine racemase (adenosine triphosphate-hydrolysing)
  • gramicidin S synthetase I

PathwayEdit

  • Phenylalanine Metabolism

SubstrateEdit

  • L – Phenylalanine

ProductEdit

  • D - Phenylalanine

CofactorEdit

  • Pyridoxal-phosphate (active form of vitamin B6)

Links to diseaseEdit

Problems in the digestion of phenylalanine (phe) to tyrosine (tyr) lead to the buildup of both phe and phenylpyruvate, in a disease called Phenylketonuria (PKU). These two compounds build up in the blood stream and cerebral spinal fluid, which can lead to mental retardation if left untreated. Treatment consists of a restricted diet of foods that contain phe or compounds that can breakdown into phe. Children in the US are routinely tested for this at birth. For more information see the Phenylketonuria page or the link below.

Quick factsEdit

  • pH Range = 7.2 – 8.6
  • Equilibrium Ratio:
    L-Phe:D-Phe = 3:7
  • Specific Activity: 0.019

The reactionEdit

L-PhenylalaninePhenylalanine RacemaseD-Phenylalanine
L-Phenylalanine wpmp.png D-Phenylalanine.png
ATPAMP+PP
Biochem reaction arrow forward YYNN horiz med.svg
 
 

Compound C00079 at KEGG Pathway Database. Compound C00002 at KEGG Pathway Database. Enzyme 5.1.1.11 at KEGG Pathway Database. Compound C00020 at KEGG Pathway Database. Compound C00013 at KEGG Pathway Database. Compound C00001 at KEGG Pathway Database. Reaction R00686 at KEGG Pathway Database. Pathway MAP00360 at KEGG Pathway Database. Compound C00018 at KEGG Pathway Database. |}

This article uses material from the Wikipedia article
 Metasyntactic variable, which is released under the 
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