Sandbox Reserved 770: Difference between revisions

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Most of the conserved active site residues are contained within seven stabilizing alpha helices, represented by Figure 6. These residues include: Leu266, Asn270, Val269, Leu215, Lys486, and Ile472.<ref name=rutgers>http://maptest.rutgers.edu/drupal/?q=node/408</ref> Six positive alpha helices point toward the active site in association with MIO cofactor. This association will not only increase the electrophilicity of MIO, but also increases he positive charge of highly conserved Lys468 residue. The positive poles are suitable for stabilizing a carbanionic charge produced by an elimination unimolecular conjugate base (E1cB) mechanism of substrate phenylalanine, in accordance with MIO cofactor. Stabilization of the carbanion reduces pKa of the C3 methylidine group of phenylalanine, promoting the interactions between the negatively charged carboxylate end of phenylalanine to the active site of PAL.

[[Image:Stabilizing_residues_of_PAL_active_site.png|thumb|left|Figure 7. Lys468 residue always adjacent to Gly residue]]

==Conserved Residues in Catalysis==

'''Lysine468'''

The positively charged side chain of Lys468 recognizes the carboxyl group of substrate by forming a salt bridge, when it is located in the mouth of the funnel. Before the side chain encloses, Lysine chaperones the substrate to its reactive position for sharing additional interactions between substrate's carboxyl group and side chains Glu496 and Gln500. Lys468 is strictly conserved with almost always adjacent Gly ~~amino acid~~, which would improve mobility of Lys486 chaperone ability for substrate. Lys486 also acts to place the NH2 group of the substrate near MIO to ensure the carboxylate group of substrate does not react nonproductively with methylidene of MIO by forming an ester.

The positively charged side chain of Lys468 recognizes the carboxyl group of substrate by forming a salt bridge, when it is located in the mouth of the funnel. Before the side chain encloses, Lysine chaperones the substrate to its reactive position for sharing additional interactions between substrate's carboxyl group and side chains Glu496 and Gln500. Lys468 is strictly conserved with almost always adjacent Gly residue, which would improve mobility of Lys486 chaperone ability for substrate. Lys486 also acts to place the NH2 group of the substrate near MIO to ensure the carboxylate group of substrate does not react nonproductively with methylidene of MIO by forming an ester.

'''Histidine137'''

Sandbox Reserved 770: Difference between revisions

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@@ Line 69: / Line 69: @@
 Most of the conserved active site residues are contained within seven stabilizing alpha helices, represented by Figure 6. These residues include: Leu266, Asn270, Val269, Leu215, Lys486, and Ile472.<ref name=rutgers>http://maptest.rutgers.edu/drupal/?q=node/408</ref> Six positive alpha helices point toward the active site in association with MIO cofactor. This association will not only increase the electrophilicity of MIO, but also increases he positive charge of highly conserved Lys468 residue. The positive poles are suitable for stabilizing a carbanionic charge produced by an elimination unimolecular conjugate base (E1cB) mechanism of substrate phenylalanine, in accordance with MIO cofactor. Stabilization of the carbanion reduces pKa of the C3 methylidine group of phenylalanine, promoting the interactions between the negatively charged carboxylate end of phenylalanine to the active site of PAL.
+[[Image:Stabilizing_residues_of_PAL_active_site.png|thumb|left|Figure 7. Lys468 residue always adjacent to Gly residue]]
 ==Conserved Residues in Catalysis==
 '''Lysine468'''
-The positively charged side chain of Lys468 recognizes the carboxyl group of substrate by forming a salt bridge, when it is located in the mouth of the funnel. Before the side chain encloses, Lysine chaperones the substrate to its reactive position for sharing additional interactions between substrate's carboxyl group and side chains Glu496 and Gln500. Lys468 is strictly conserved with almost always adjacent Gly amino acid, which would improve mobility of Lys486 chaperone ability for substrate. Lys486 also acts to place the NH2 group of the substrate near MIO to ensure the carboxylate group of substrate does not react nonproductively with methylidene of MIO by forming an ester.
+The positively charged side chain of Lys468 recognizes the carboxyl group of substrate by forming a salt bridge, when it is located in the mouth of the funnel. Before the side chain encloses, Lysine chaperones the substrate to its reactive position for sharing additional interactions between substrate's carboxyl group and side chains Glu496 and Gln500. Lys468 is strictly conserved with almost always adjacent Gly residue, which would improve mobility of Lys486 chaperone ability for substrate. Lys486 also acts to place the NH2 group of the substrate near MIO to ensure the carboxylate group of substrate does not react nonproductively with methylidene of MIO by forming an ester.
 '''Histidine137'''