Sandbox Reserved 349: Difference between revisions

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='''Porphobilinogen Deaminase'''=

Porphobilinogen deaminase (PBGD) also known as Hydroxymethylbilane synthase, is a ~~dimeric~~ polypeptide and is the third enzyme in the heme biosynthesis pathways in mammals<ref name="Raj">PMID: 19207107</ref>. It catalyses the polymerization of four porphobilinogen molecules to yield hydroxymethylbilane, a precursor in the formation of [[Porphyrin]]<ref name="Peter">PMID:3079571</ref>. Porphobilinogen deaminases are able to form surprisingly stable enzyme-substrate complexes with up to four pyrrole substrates interacting with the active site, a feature unique to the group of enzymes<ref name="Anderson">PMID:7354069</ref>. <scene name='Sandbox_Reserved_349/Dpm/1'>Dipyrromethane (DPM)</scene>, a cofactor unique to porphobilinogen deaminases, is thought to stabilize these interactions at each of the two active domains<ref name="Peter">PMID:3079571</ref>. Mutations in the human PBGD gene are responsible for the condition Acute Intermittent Porphyria (AIP) in humans<ref name="Raj">PMID: 19207107</ref>.

Porphobilinogen deaminase (PBGD) also known as Hydroxymethylbilane synthase, is a monomeric polypeptide and is the third enzyme in the heme biosynthesis pathways in mammals<ref name="Raj">PMID: 19207107</ref>. It catalyses the polymerization of four porphobilinogen molecules to yield hydroxymethylbilane, a precursor in the formation of [[Porphyrin]]<ref name="Peter">PMID:3079571</ref>. Porphobilinogen deaminases are able to form surprisingly stable enzyme-substrate complexes with up to four pyrrole substrates interacting with the active site, a feature unique to the group of enzymes<ref name="Anderson">PMID:7354069</ref>. <scene name='Sandbox_Reserved_349/Dpm/1'>Dipyrromethane (DPM)</scene>, a cofactor unique to porphobilinogen deaminases, is thought to stabilize these interactions at each of the two active domains<ref name="Peter">PMID:3079571</ref>. Mutations in the human PBGD gene are responsible for the condition Acute Intermittent Porphyria (AIP) in humans<ref name="Raj">PMID: 19207107</ref>.

=Structure=

Human PBGD is a three-domain polypeptide with each domain consisting of approximately 110 amino acids<ref name="Raj">PMID: 19207107</ref>. In the active site, a unique molecule known as <scene name='Template:Sandbox_Reserved_349/Dpm_site/2'>Dipyrromethane</scene> interacts with porphobilinogen and anchors it in place<ref name="Raj">PMID: 19207107</ref>. Ordered sulfate ions are also hydrogen bonded with Arg26 and Ser28 residues near the active site that are highly conserved amongst human and ''E.coli'' variants of PBGD<ref name="Raj">PMID: 19207107</ref>.

Although PBGD appears to have hydrogen bonding capabilities between two identical PBGD units, at physiological pH, these interactions account for a dimer interface of approximately 5% while average dimer interface between subunits is 16%<ref name="Raj">PMID: 19207107</ref>. Therefore, it is generally assumed that this protein is active naturally as a monomeric enyme<ref name="Raj">PMID: 19207107</ref>.

=Function=

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 ='''Porphobilinogen Deaminase'''=
 {{STRUCTURE_3eq1 |  PDB=3eq1  |  SCENE= }}
-Porphobilinogen deaminase (PBGD) also known as Hydroxymethylbilane synthase, is a dimeric polypeptide and is the third enzyme in the heme biosynthesis pathways in mammals<ref name="Raj">PMID: 19207107</ref>. It catalyses the polymerization of  four porphobilinogen molecules to yield	hydroxymethylbilane, a precursor in the formation of [[Porphyrin]]<ref name="Peter">PMID:3079571</ref>. Porphobilinogen deaminases  are able to form surprisingly stable enzyme-substrate complexes with up to four pyrrole substrates interacting with the active site, a feature unique to the group of enzymes<ref name="Anderson">PMID:7354069</ref>. <scene name='Sandbox_Reserved_349/Dpm/1'>Dipyrromethane (DPM)</scene>, a cofactor unique to porphobilinogen deaminases, is thought to stabilize these interactions at each of the two active domains<ref name="Peter">PMID:3079571</ref>. Mutations in the human PBGD gene are responsible for the condition Acute Intermittent Porphyria (AIP) in humans<ref name="Raj">PMID: 19207107</ref>.
+Porphobilinogen deaminase (PBGD) also known as Hydroxymethylbilane synthase, is a monomeric polypeptide and is the third enzyme in the heme biosynthesis pathways in mammals<ref name="Raj">PMID: 19207107</ref>. It catalyses the polymerization of  four porphobilinogen molecules to yield	hydroxymethylbilane, a precursor in the formation of [[Porphyrin]]<ref name="Peter">PMID:3079571</ref>. Porphobilinogen deaminases  are able to form surprisingly stable enzyme-substrate complexes with up to four pyrrole substrates interacting with the active site, a feature unique to the group of enzymes<ref name="Anderson">PMID:7354069</ref>. <scene name='Sandbox_Reserved_349/Dpm/1'>Dipyrromethane (DPM)</scene>, a cofactor unique to porphobilinogen deaminases, is thought to stabilize these interactions at each of the two active domains<ref name="Peter">PMID:3079571</ref>. Mutations in the human PBGD gene are responsible for the condition Acute Intermittent Porphyria (AIP) in humans<ref name="Raj">PMID: 19207107</ref>.
 =Structure=
 Human PBGD is a three-domain polypeptide with each domain consisting of approximately 110 amino acids<ref name="Raj">PMID: 19207107</ref>. In the active site, a unique molecule known as <scene name='Template:Sandbox_Reserved_349/Dpm_site/2'>Dipyrromethane</scene> interacts with porphobilinogen and anchors it in place<ref name="Raj">PMID: 19207107</ref>. Ordered sulfate ions are also hydrogen bonded with Arg26 and Ser28 residues near the active site that are highly conserved amongst human and ''E.coli'' variants of PBGD<ref name="Raj">PMID: 19207107</ref>.
+Although PBGD appears to have hydrogen bonding capabilities between two identical PBGD units, at physiological pH, these interactions account for a dimer interface of approximately 5% while average dimer interface between subunits is 16%<ref name="Raj">PMID: 19207107</ref>. Therefore, it is generally assumed that this protein is active naturally as a monomeric enyme<ref name="Raj">PMID: 19207107</ref>.
 =Function=