Sandbox Reserved 773: Difference between revisions

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[[Image:4e1o asr r 500.jpg|frame|right|Figure 1. Asymmetrical unit of Histidine Decarboxylase formed by 3 homodimer-subunits)]]

'''Histidine Decarboxylase (HDC)''' is an enzyme that is responsible for converting histamine from amino acid L-histidine. This enzyme belongs in the group II pyridoxal-5-phosphate (PLP)-dependent decarboxylase family ~~<ref name=uniprot/> <ref name=4e10/>~~. As the name suggested, this enzyme catalyzes the production of histamine by the removal of carboxylate group from the amino acid L-histidine whilst ~~utilize~~ pyridoxal phosphate as a cofactor <ref name=~~fun>PMID: 15612036<~~/~~ref~~>.

'''Histidine Decarboxylase (HDC)''' is an enzyme that is responsible for converting histamine from amino acid L-histidine. This enzyme belongs in the group II pyridoxal-5-phosphate (PLP)-dependent decarboxylase family . As the name suggested, this enzyme catalyzes the production of histamine by the removal of carboxylate group from the amino acid L-histidine whilst utilizes on pyridoxal phosphate as a cofactor <ref name=metabolism/>

The mammalian Histamine decarboxylase is originated from HDC gene which encodes a 74kDa precursor polypeptide. However, the enzyme becomes active after undergo post-translation proteolysis when its C-terminal is truncated into 54kDa <ref name=tag>PMID: 6425286</ref> <ref name=mast/> <ref name=metabolism>Schwelberger, Hubert G. "Metabolism of Histamine." ''European Histamine Research Society'' Nov. 2013. Web. 29 Nov. 2013. http://www.ehrs.org.uk/schwelberger.pdf</ref>.

Due to the fact that histamine is a mediator that triggers inflammation response associated with allergic reaction, HDC an important enzyme to study for the development of drugs or treatments for allergic disease <ref name=metabolism/> <ref name=fun>PMID: 15612036</ref>.

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== Sequence and Structure ==

Histidine Decarboxylase is considered to be a homo-dimer when one observe its [[biological assembly]]. A homo-dimer is a [[quaternary structure]] formed by two identical monomers or protein chains. In human, three human HDC (hHDC) homo-dimers can be joined together to form a trimer [[asymmetric unit]] <ref name=jbc/> <ref name=xray>PMID: 22684068</ref>. Thus, one can use the nomenclature “trimer of dimer” to suggest the complex might dissociate into smaller subunits before dissociating into monomers. The asymmetrical unit can be seen in Figure 1. Specifically, Cystein-180 and Cystein-418 are primary responsible for the oligomerization process of HDC <ref name=xray/>.

Histidine Decarboxylase is considered to be a homo-dimer when one observe its [[biological assembly]] <ref name=mast/>. A homo-dimer is a [[quaternary structure]] formed by two identical monomers or protein chains. In human, three human HDC (hHDC) homo-dimers can be joined together to form a trimer [[asymmetric unit]] <ref name=jbc/> <ref name=xray>PMID: 22684068</ref>. Thus, one can use the nomenclature “trimer of dimer” to suggest the complex might dissociate into smaller subunits before dissociating into monomers. The asymmetrical unit can be seen in Figure 1. Specifically, Cystein-180 and Cystein-418 are primary responsible for the oligomerization process of HDC <ref name=xray/>.

Each monomer is divided into 3 structural domains: N-terminal (2-71), large domain (71-371), and small domain (372-477) (green link/figure 5) <ref name=jbc/>. A monomer is also composed of 49% helical structure and 13% beta sheet <ref name=4e10/>. One specifically long α-helix which span from Valine-359 to Arginine-393 connects the large and small domains together (Figure 2). Through hydrophobic effect, the N-terminal regions of the two monomers interact with each other extensively. At the same time, the large domains interact extensively due to electrostatic interactions. Thus, the N-terminal regions and large domains form the dimer interfaces of HDC <ref name=jbc/>.

Sandbox Reserved 773: Difference between revisions

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@@ Line 8: / Line 8: @@
 [[Image:4e1o asr r 500.jpg|frame|right|Figure 1. Asymmetrical unit of Histidine Decarboxylase formed by 3 homodimer-subunits)]]
-'''Histidine Decarboxylase (HDC)''' is an enzyme that is responsible for converting histamine from amino acid L-histidine. This enzyme belongs in the group II pyridoxal-5-phosphate (PLP)-dependent decarboxylase family <ref name=uniprot/> <ref name=4e10/>. As the name suggested, this enzyme catalyzes the production of histamine by the removal of carboxylate group from the amino acid L-histidine whilst utilize pyridoxal phosphate as a cofactor <ref name=fun>PMID: 15612036</ref>.
+'''Histidine Decarboxylase (HDC)''' is an enzyme that is responsible for converting histamine from amino acid L-histidine. This enzyme belongs in the group II pyridoxal-5-phosphate (PLP)-dependent decarboxylase family . As the name suggested, this enzyme catalyzes the production of histamine by the removal of carboxylate group from the amino acid L-histidine whilst utilizes on pyridoxal phosphate as a cofactor <ref name=metabolism/>
 The mammalian Histamine decarboxylase is originated from HDC gene which encodes a 74kDa precursor polypeptide. However, the enzyme becomes active after undergo post-translation proteolysis when its C-terminal is truncated into 54kDa <ref name=tag>PMID: 6425286</ref> <ref name=mast/> <ref name=metabolism>Schwelberger, Hubert G. "Metabolism of Histamine." ''European Histamine Research Society'' Nov. 2013. Web. 29 Nov. 2013. http://www.ehrs.org.uk/schwelberger.pdf</ref>.
+Due to the fact that histamine is a mediator that triggers inflammation response associated with allergic reaction, HDC an important enzyme to study for the development of drugs or treatments for allergic disease <ref name=metabolism/> <ref name=fun>PMID: 15612036</ref>.
 __TOC__
@@ Line 43: / Line 44: @@
 == Sequence and Structure ==
-Histidine Decarboxylase is considered to be a homo-dimer when one observe its [[biological assembly]]. A homo-dimer is a [[quaternary structure]] formed by two identical monomers or protein chains. In human, three human HDC (hHDC) homo-dimers can be joined together to form a trimer [[asymmetric unit]] <ref name=jbc/> <ref name=xray>PMID: 22684068</ref>. Thus, one can use the nomenclature “trimer of dimer” to suggest the complex might dissociate into smaller subunits before dissociating into monomers. The asymmetrical unit can be seen in Figure 1. Specifically, Cystein-180 and Cystein-418 are primary responsible for the oligomerization process of HDC <ref name=xray/>.
+Histidine Decarboxylase is considered to be a homo-dimer when one observe its [[biological assembly]] <ref name=mast/>. A homo-dimer is a [[quaternary structure]] formed by two identical monomers or protein chains. In human, three human HDC (hHDC) homo-dimers can be joined together to form a trimer [[asymmetric unit]] <ref name=jbc/> <ref name=xray>PMID: 22684068</ref>. Thus, one can use the nomenclature “trimer of dimer” to suggest the complex might dissociate into smaller subunits before dissociating into monomers. The asymmetrical unit can be seen in Figure 1. Specifically, Cystein-180 and Cystein-418 are primary responsible for the oligomerization process of HDC <ref name=xray/>.
 Each monomer is divided into 3 structural domains: N-terminal (2-71), large domain (71-371), and small domain (372-477) (green link/figure 5) <ref name=jbc/>. A monomer is also composed of 49% helical structure and 13% beta sheet <ref name=4e10/>. One specifically long α-helix which span from Valine-359 to Arginine-393 connects the large and small domains together (Figure 2). Through hydrophobic effect, the N-terminal regions of the two monomers interact with each other extensively. At the same time, the large domains interact extensively due to electrostatic interactions. Thus, the N-terminal regions and large domains form the dimer interfaces of HDC <ref name=jbc/>.