Sandbox Reserved 325: Difference between revisions
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=Chorismate Mutase= | =Chorismate Mutase= | ||
==Introduction== | ==Introduction== | ||
The gene Rv1885c from ''Mycobacteria tuberculosis'' encodes for a non-functional chorismate mutase (*MtCM)<ref name="pizza" />. This non-functional mutase has a 33-amino-acid cleavable sequence <ref name="pizza" />. Chorismate mutase is a vital enzyme in the shikimate pathway, which allows for the synthesis of tryptophan, tyrosine, and phenylalanine <ref name="pizza" />. This protein acts at the first branch point of the shikimate pathway, making it a regulating step in the conversion of prephenate from chorismate<ref name="CMW2"> PMID:11481470 </ref>. | The gene Rv1885c from ''Mycobacteria tuberculosis'' encodes for a non-functional chorismate mutase (*MtCM)<ref name="pizza" />. This non-functional mutase has a 33-amino-acid cleavable sequence <ref name="pizza" />. Chorismate mutase is a vital enzyme in the shikimate pathway, which allows for the synthesis of tryptophan, tyrosine, and phenylalanine <ref name="pizza" />. This protein acts at the first branch point of the shikimate pathway, making it a regulating step in the conversion of prephenate from chorismate<ref name="CMW2"> PMID:11481470 </ref>. Since chorismate mutase catalyzes a claisen rearrangement it can be considered an isomerase since it catalyzes rearrangements of isomers. Chorismate mutase provides a 2x10<sup>6</sup> fold increase in the rate of reaction in comparision to the uncatalyzed reaction <ref > P.D. Lyne, A.J. Mulholland, W.G. Richards. Insights into chorismate mutase catalysis from a combined qm/mm simulation of the enzyme reaction. Journal of the American Chemistry Society. 1995 117(45):11345-11350</ref>. | ||
Chorismate mutase provides a 2x10<sup>6</sup> fold increase in the rate of reaction in comparision to the uncatalyzed reaction <ref > P.D. Lyne, A.J. Mulholland, W.G. Richards. Insights into chorismate mutase catalysis from a combined qm/mm simulation of the enzyme reaction. Journal of the American Chemistry Society. 1995 117(45):11345-11350</ref>. | |||
Chorismate mutase only occurs in bacteria, higher plants, and fungi, due to the fact that the shikimate pathway is only found in these organisms <ref name="strat" />. In ''Escherichia coli'', chorismate mutase has a periplasmic destination<ref name="pizza" />. In ''M. tuberculosis'' there is in abscence of a periplasmic compartment for chorismate mutase, so it secretes into the culture filtrate of ''M. tuberculosis''<ref name="pizza" />. It is believed that a pseudoperiplasmic space might exist in ''M. tuberculosis''<ref name="pizza" />. | Chorismate mutase only occurs in bacteria, higher plants, and fungi, due to the fact that the shikimate pathway is only found in these organisms <ref name="strat" />. In ''Escherichia coli'', chorismate mutase has a periplasmic destination<ref name="pizza" />. In ''M. tuberculosis'' there is in abscence of a periplasmic compartment for chorismate mutase, so it secretes into the culture filtrate of ''M. tuberculosis''<ref name="pizza" />. It is believed that a pseudoperiplasmic space might exist in ''M. tuberculosis''<ref name="pizza" />. | ||
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==Mechanism== | ==Mechanism== | ||
in Michaelis-Menten kinetics it has Km of 0.5 ± 0.05 mM and Kcat of 60 s<sup>-1 </sup> <ref name="pizza" />. | in Michaelis-Menten kinetics it has Km of 0.5 ± 0.05 mM and Kcat of 60 s<sup>-1 </sup> <ref name="pizza" />. | ||
Chorismate mutase is an essential enzyme in the shikimate pathway <ref name="pizza"> PMID:17146044 </ref>. This pathway allows for the biosynthesis of aromatic amino acids tryptophan, tyrosine, and phenylalanine <ref name="pizza" />. The production of tyrosine and phenylalanine is achieved by what is called a Claisen | Chorismate mutase is an essential enzyme in the shikimate pathway <ref name="pizza"> PMID:17146044 </ref>. This pathway allows for the biosynthesis of aromatic amino acids tryptophan, tyrosine, and phenylalanine <ref name="pizza" />. The production of tyrosine and phenylalanine is achieved by what is called a Claisen rearrangement. first converting chorismate to prephenate. Prephenate then reacts with prephenate dehydratase and prephenate dehydrogenase which forms phenylpyruvate and hydroxyphenylpyruvate. After this occurs, aminotransferase converts hydroxy-phenylpyruvate and phenylpyruvate to phenylalanine and tyrosine. Chorismate mutase provides a 2x10<sup>6</sup> fold increase in the rate of reaction, in comparison to the uncatalyzed reaction <ref > P.D. Lyne, A.J. Mulholland, W.G. Richards. Insights into chorismate mutase catalysis from a combined qm/mm simulation of the enzyme reaction. Journal of the American Chemistry Society. 1995 117(45):11345-11350</ref>. It is the only example of an enzyme catalyzing a percyclic reaction <ref name="strat"> PMID:10960481 </ref> | ||
Chorismate mutase has optimal performance at 37 degrees Celcius and at pH 7.5, but it can still optimally a pH range from pH 4.0 to 7.5 <ref name="pizza" /> | Chorismate mutase has optimal performance at 37 degrees Celcius and at pH 7.5, but it can still optimally a pH range from pH 4.0 to 7.5 <ref name="pizza" /> | ||
