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=== | ||
The active site of DOPA decarboxylase is located in a cleft at the <scene name='DOPA_decarboxylase/Dimer_interface/2'>interface</scene> between the two subunits of the dimer, like all PLP-dependent enzymes of the aspartate aminotransferase family. Since it is at the interface, residues from both domains and both subunits are involved in cofactor binding, although the active site is composed of residues mainly from one monomer. The <scene name='DOPA_decarboxylase/Active_site/1'>active site</scene> is composed of several key residues. <scene name='DOPA_decarboxylase/Lysine2/1'>Lys303</scene> serves to bind PLP via a [http://en.wikipedia.org/wiki/Schiff_base Schiff base] linkage in the absence on substrate. | |||
[[image:plp bound.png|thumb|center|400px|'''Schiff base linkage of PLP to Lys303 in the active site''']] | [[image:plp bound.png|thumb|center|400px|'''Schiff base linkage of PLP to Lys303 in the active site''']] | ||
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