DOPA decarboxylase: Difference between revisions
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====Quaternary Structure==== | ====Quaternary Structure==== | ||
The level of protein structure exists solely in multisubunit complexes. DOPA decarboxylase is a homodimeric enzyme with the active site located near the monomer-monomer interface, thus highlighting the importance of this level of protein structure to the enzymes function. Furthermore, since the N-terminal domain of one monomer packs on top of the other monomer, resulting in an extended dimer interface, this level of tertiary structure is most likely stable only in the dimeric form of the enzyme. | The level of protein structure exists solely in multisubunit complexes. DOPA decarboxylase is a homodimeric enzyme with the active site located near the monomer-monomer interface, thus highlighting the importance of this level of protein structure to the enzymes function. Furthermore, since the N-terminal domain of one monomer packs on top of the other monomer, resulting in an extended dimer interface, this level of tertiary structure is most likely stable only in the dimeric form of the enzyme. | ||
==Function== | ==Function== | ||
===The Active Site=== | ===The Active Site=== | ||
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The only two active site residues from the adjacent monomer, Ile-101 and Phe-103, are part of the substrate binding pocket. | The only two active site residues from the adjacent monomer, Ile-101 and Phe-103, are part of the substrate binding pocket. | ||
===Inhibitor Binding=== | ===Inhibitor Binding=== | ||
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[[image:l-dopa.png|thumb|200px|'''L-DOPA''']][[image:carbiDOPA.png|thumb|200px|'''carbiDOPA''']] [[image:benserazide.png|thumb|200px|'''benserazide''']] | [[image:l-dopa.png|thumb|200px|'''L-DOPA''']][[image:carbiDOPA.png|thumb|200px|'''carbiDOPA''']] [[image:benserazide.png|thumb|200px|'''benserazide''']] | ||
The inhibitor <scene name='Sandbox/Active_site3/1'>carbiDOPA</scene> binds to the enzyme by forming a hydrazone linkage with PLP through its hydrazine moiety. The catechol ring of carbiDOPA is deeply buried in the active site cleft and is stabilized by <scene name='DOPA_decarboxylase/Vanderwaals/1'>van der waals contact</scene> with Ile-101 and Phe-103. The 4' hydroxyl group of the catechol ring participates in hydrogen bonding with <scene name='DOPA_decarboxylase/Thr-82/1'>Thr-82</scene>, further stabilizing the inhibitor in the active site cleft. | The inhibitor <scene name='Sandbox/Active_site3/1'>carbiDOPA</scene> binds to the enzyme by forming a hydrazone linkage with PLP through its hydrazine moiety. The catechol ring of carbiDOPA is deeply buried in the active site cleft and is stabilized by <scene name='DOPA_decarboxylase/Vanderwaals/1'>van der waals contact</scene> with Ile-101 and Phe-103. The 4' hydroxyl group of the catechol ring participates in hydrogen bonding with <scene name='DOPA_decarboxylase/Thr-82/1'>Thr-82</scene>, further stabilizing the inhibitor in the active site cleft. PLP is also involved in substrate binding, as it hydrogen bonds to the 3' of the catechol ring. <scene name='DOPA_decarboxylase/His192/1'>His-192</scene>, a highly conserved residue of PLP-dependent decarboxylases <ref name="ishii">PMID:8889823 </ref> hydrogen bonds to the carboxylate group of carbiDOPA. | ||
==Classification== | ==Classification== | ||
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