Urocanase - Revision history

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	~~{{Short description\|Enzyme involved in the histidine degradation pathway}}~~		== Urocanase ==
	~~{{Use dmy dates\|date~~=~~October 2023}}~~

	~~'''Urocanase''' (also known as '''urocanate hydratase''') is an enzyme that catalyzes the reversible hydration of [[urocanic acid]] to form~~ [[~~imidazolonepropionic acid]]~~. ~~This reaction is a part~~ of ~~the [[histidine degradation pathway~~]] ~~in many organisms, including bacteria, fungi, and mammals.~~		[[File:PDB_2fkn_EBI.png\|thumb\|right\|Crystal structure of urocanase (PDB ID: 2fkn)]]

	~~==Structure==~~		'''Urocanase''' is an enzyme that plays a crucial role in the [[histidine]] degradation pathway. It catalyzes the conversion of [[urocanic acid]] to [[imidazolonepropionic acid]], a key step in the catabolism of histidine. This enzyme is found in various organisms, including bacteria, fungi, and mammals.
	Urocanase is a ~~member of~~ the [[~~amidohydrolase superfamily~~]] ~~and typically functions as a homodimer~~. ~~The enzyme contains a tightly bound~~ [[~~NAD+~~]] ~~cofactor, which is unusual because NAD+ is not consumed in the reaction. The structure of urocanase has been elucidated through~~ [[~~X-ray crystallography~~]], ~~revealing~~ a ~~complex fold that accommodates~~ the ~~substrate~~ and ~~cofactor~~.

	~~[[File:PDB_2fkn_EBI~~.~~png\|thumb\|right\|Crystal structure~~ of ~~urocanase (PDB ID: 2fkn)]]~~		== Function ==
			Urocanase is responsible for the hydration of urocanic acid, resulting in the formation of imidazolonepropionic acid. This reaction is part of the metabolic pathway that breaks down histidine, an essential amino acid, into smaller molecules that can be utilized for energy production or other biosynthetic processes.

	==~~Function~~==		== Structure ==
	~~Urocanase plays~~ a ~~crucial role in~~ the ~~catabolism of~~ [[~~L-histidine~~]], ~~an essential amino acid~~. The ~~enzyme facilitates the conversion~~ of ~~urocanic acid~~, ~~which is produced from histidine by~~ the ~~action~~ of ~~[[histidine ammonia~~-~~lyase]], into imidazolonepropionic acid. This step is essential for~~ the ~~subsequent production of [[glutamate]] and other metabolites~~.		The enzyme urocanase is a member of the [[amidohydrolase]] superfamily. It typically functions as a homodimer, with each subunit contributing to the active site. The crystal structure of urocanase, as shown in the image, reveals a complex arrangement of alpha-helices and beta-sheets that form the active site pocket where the substrate binds.

	==Mechanism==		== Mechanism ==
	~~The enzymatic~~ mechanism ~~of urocanase~~ involves the addition of a water molecule across the double bond of ~~urocanic acid, forming imidazolonepropionic acid~~. ~~The~~ NAD+ cofactor is ~~believed~~ to ~~stabilize the~~ reaction ~~intermediate~~, although it ~~is not reduced during~~ the ~~process~~.		Urocanase catalyzes the hydration of urocanic acid through a mechanism that involves the addition of a water molecule across the double bond of the imidazole ring. This reaction is facilitated by the presence of a tightly bound [[NAD+]] cofactor, which is essential for the enzyme's activity. The conversion of urocanic acid to imidazolonepropionic acid is a reversible reaction, although in vivo it proceeds predominantly in the forward direction.

	~~[[File:Imidazol-4-one-5-propionic_acid~~.~~png\|thumb\|right\|Chemical structure~~ of imidazolonepropionic acid]]		== Biological Significance ==
			In humans, urocanase is primarily found in the liver, where it participates in the degradation of dietary histidine. The product of the urocanase reaction, imidazolonepropionic acid, is further metabolized to form [[glutamic acid]], which can then enter the [[tricarboxylic acid cycle]] for energy production. Deficiencies in urocanase activity can lead to the accumulation of urocanic acid, which has been associated with certain metabolic disorders.

	==~~Biological significance~~==		== Clinical Relevance ==
	~~In humans, urocanase~~ is ~~primarily found~~ in the ~~liver~~, ~~where it participates in the breakdown of dietary histidine~~. ~~Deficiency in urocanase activity can lead to~~ the ~~accumulation~~ of urocanic acid~~, which is excreted~~ in urine~~, a condition known as [[urocanic aciduria]]~~.		Urocanase deficiency is a rare metabolic disorder that can result in elevated levels of urocanic acid in the body. This condition, known as urocanic aciduria, may present with symptoms such as developmental delay and skin abnormalities. Diagnosis is typically made through the detection of increased urocanic acid in the urine.

	==Related ~~pages~~==		== Related Pages ==
	* [[Histidine ~~degradation pathway~~]]		* [[Histidine metabolism]]
	* [[Amidohydrolase ~~superfamily~~]]		* [[Amidohydrolase]]
	* [[NAD+]]		* [[NAD+]]
			* [[Tricarboxylic acid cycle]]

	~~==References==~~		[[File:Imidazol-4-one-5-propionic_acid.png\|thumb\|right\|Chemical structure of imidazolonepropionic acid]]
	~~{{Reflist}}~~

	[[Category:~~EC 4.2.1~~]]		{{Enzyme-stub}}
			{{Metabolism-stub}}

			[[Category:Enzymes]]
			[[Category:Metabolism]]
	[[Category:Histidine metabolism]]		[[Category:Histidine metabolism]]
	~~[[Category:Enzymes]]~~
	~~<gallery>~~
	~~File:Imidazol-4-one-5-propionic_acid.png\|Chemical structure of Imidazol-4-one-5-propionic acid~~
	~~</gallery>~~
	~~== Urocanase ==~~
	~~<gallery>~~
	~~File:PDB_2fkn_EBI.png\|Structure of Urocanase enzyme~~
	~~File:Imidazol-4-one-5-propionic_acid.png\|Imidazol-4-one-5-propionic acid~~
	~~</gallery>~~

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	<gallery>		<gallery>
	File:Imidazol-4-one-5-propionic_acid.png\|Chemical structure of Imidazol-4-one-5-propionic acid		File:Imidazol-4-one-5-propionic_acid.png\|Chemical structure of Imidazol-4-one-5-propionic acid
			</gallery>
			== Urocanase ==
			<gallery>
			File:PDB_2fkn_EBI.png\|Structure of Urocanase enzyme
			File:Imidazol-4-one-5-propionic_acid.png\|Imidazol-4-one-5-propionic acid
	</gallery>		</gallery>

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	[[Category:Enzymes]]		[[Category:Enzymes]]
	<gallery>		<gallery>
	~~File:Urocanase PDB_2fkn_EBI.png\|Structure of Urocanase~~
	File:Imidazol-4-one-5-propionic_acid.png\|Chemical structure of Imidazol-4-one-5-propionic acid		File:Imidazol-4-one-5-propionic_acid.png\|Chemical structure of Imidazol-4-one-5-propionic acid
	</gallery>		</gallery>

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	[[Category:Histidine metabolism]]		[[Category:Histidine metabolism]]
	[[Category:Enzymes]]		[[Category:Enzymes]]
			<gallery>
			File:Urocanase PDB_2fkn_EBI.png\|Structure of Urocanase
			File:Imidazol-4-one-5-propionic_acid.png\|Chemical structure of Imidazol-4-one-5-propionic acid
			</gallery>

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	=~~= Urocanase ==~~		{{Short description\|Enzyme involved in the histidine degradation pathway}}
			{{Use dmy dates\|date=October 2023}}

	Urocanase is an enzyme that ~~plays a crucial role in the metabolism of histidine, an essential amino acid. It is responsible for~~ the ~~conversion~~ of urocanic acid to ~~imidazolone propionic acid, which is further metabolized to formiminoglutamic~~ acid. This ~~enzyme~~ is ~~found~~ in ~~various~~ organisms, including bacteria, fungi~~, plants~~, and ~~animals~~.		'''Urocanase''' (also known as '''urocanate hydratase''') is an enzyme that catalyzes the reversible hydration of [[urocanic acid]] to form [[imidazolonepropionic acid]]. This reaction is a part of the [[histidine degradation pathway]] in many organisms, including bacteria, fungi, and mammals.

	=== Structure ===		==Structure==
			Urocanase is a member of the [[amidohydrolase superfamily]] and typically functions as a homodimer. The enzyme contains a tightly bound [[NAD+]] cofactor, which is unusual because NAD+ is not consumed in the reaction. The structure of urocanase has been elucidated through [[X-ray crystallography]], revealing a complex fold that accommodates the substrate and cofactor.

	~~Urocanase is a homodimeric enzyme, meaning it consists of two identical subunits~~. ~~Each subunit contains approximately 300 amino acids and has a molecular weight~~ of ~~around 33 kDa. The enzyme has been extensively studied in different organisms, and its crystal structure has been determined in several species, including humans and bacteria.~~		[[File:PDB_2fkn_EBI.png\|thumb\|right\|Crystal structure of urocanase (PDB ID: 2fkn)]]

	=== Function ===		==Function==
			Urocanase plays a crucial role in the catabolism of [[L-histidine]], an essential amino acid. The enzyme facilitates the conversion of urocanic acid, which is produced from histidine by the action of [[histidine ammonia-lyase]], into imidazolonepropionic acid. This step is essential for the subsequent production of [[glutamate]] and other metabolites.

	The ~~primary function~~ of urocanase ~~is to catalyze~~ the ~~conversion~~ of urocanic acid, ~~a metabolite of histidine, to imidazolone propionic~~ acid. ~~This reaction~~ is ~~an essential step in~~ the ~~histidine degradation pathway. Imidazolone propionic acid~~ is ~~subsequently converted to formiminoglutamic acid by~~ the ~~action of another enzyme called imidazolonepropionase~~.		==Mechanism==
			The enzymatic mechanism of urocanase involves the addition of a water molecule across the double bond of urocanic acid, forming imidazolonepropionic acid. The NAD+ cofactor is believed to stabilize the reaction intermediate, although it is not reduced during the process.

	~~=== Role in Histidine Metabolism ===~~		[[File:Imidazol-4-one-5-propionic_acid.png\|thumb\|right\|Chemical structure of imidazolonepropionic acid]]

	~~Histidine~~ is ~~an essential amino acid that is obtained through~~ dietary ~~sources~~. ~~It plays a vital role~~ in ~~protein synthesis, neurotransmission, and~~ the ~~production~~ of ~~various molecules~~, ~~such~~ as ~~histamine and carnosine. However, excess histidine needs to be metabolized to maintain proper physiological balance~~.		==Biological significance==
			In humans, urocanase is primarily found in the liver, where it participates in the breakdown of dietary histidine. Deficiency in urocanase activity can lead to the accumulation of urocanic acid, which is excreted in urine, a condition known as [[urocanic aciduria]].

	~~Urocanase is involved in the breakdown of histidine, specifically in the conversion of urocanic acid to imidazolone propionic acid. This step allows for the further~~ degradation ~~of histidine and the eventual production of formiminoglutamic acid, which can be further metabolized to produce glutamic acid.~~		==Related pages==
			* [[Histidine degradation pathway]]
			* [[Amidohydrolase superfamily]]
			* [[NAD+]]

	~~=== Clinical Significance ===~~		==References==
			{{Reflist}}
	Mutations in the urocanase gene can lead to a rare genetic disorder known as urocanic aciduria. This condition is characterized by the accumulation of urocanic acid in the body, resulting in various symptoms, including intellectual disability, seizures, and developmental delays. Urocanic aciduria is inherited in an autosomal recessive manner.

	=== References ===

	~~1. [[Histidine metabolism\|Histidine Metabolism]] - Wikipedia article on histidine metabolism.~~
	~~2. [[Amino acid metabolism\|Amino Acid Metabolism]] - Wikipedia article on amino acid metabolism.~~
	~~3. [[Urocanic aciduria\|Urocanic Aciduria]] - Rare Diseases Database article on urocanic aciduria.~~

	~~== See Also ==~~

	* [[Histidine]]
	* [[Enzyme]]
	* [[Amino Acid Metabolism]]
	* [[Genetic Disorder]]

			[[Category:EC 4.2.1]]
			[[Category:Histidine metabolism]]
	[[Category:Enzymes]]		[[Category:Enzymes]]
	~~[[Category:Amino acids]]~~
	~~[[Category:Metabolism]]~~
	~~[[Category:Genetic disorders]]~~

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== Urocanase ==

Urocanase is an enzyme that plays a crucial role in the metabolism of histidine, an essential amino acid. It is responsible for the conversion of urocanic acid to imidazolone propionic acid, which is further metabolized to formiminoglutamic acid. This enzyme is found in various organisms, including bacteria, fungi, plants, and animals.

=== Structure ===

Urocanase is a homodimeric enzyme, meaning it consists of two identical subunits. Each subunit contains approximately 300 amino acids and has a molecular weight of around 33 kDa. The enzyme has been extensively studied in different organisms, and its crystal structure has been determined in several species, including humans and bacteria.

=== Function ===

The primary function of urocanase is to catalyze the conversion of urocanic acid, a metabolite of histidine, to imidazolone propionic acid. This reaction is an essential step in the histidine degradation pathway. Imidazolone propionic acid is subsequently converted to formiminoglutamic acid by the action of another enzyme called imidazolonepropionase.

=== Role in Histidine Metabolism ===

Histidine is an essential amino acid that is obtained through dietary sources. It plays a vital role in protein synthesis, neurotransmission, and the production of various molecules, such as histamine and carnosine. However, excess histidine needs to be metabolized to maintain proper physiological balance.

Urocanase is involved in the breakdown of histidine, specifically in the conversion of urocanic acid to imidazolone propionic acid. This step allows for the further degradation of histidine and the eventual production of formiminoglutamic acid, which can be further metabolized to produce glutamic acid.

=== Clinical Significance ===

Mutations in the urocanase gene can lead to a rare genetic disorder known as urocanic aciduria. This condition is characterized by the accumulation of urocanic acid in the body, resulting in various symptoms, including intellectual disability, seizures, and developmental delays. Urocanic aciduria is inherited in an autosomal recessive manner.

=== References ===

1. [[Histidine metabolism|Histidine Metabolism]] - Wikipedia article on histidine metabolism.
2. [[Amino acid metabolism|Amino Acid Metabolism]] - Wikipedia article on amino acid metabolism.
3. [[Urocanic aciduria|Urocanic Aciduria]] - Rare Diseases Database article on urocanic aciduria.

== See Also ==

* [[Histidine]]
* [[Enzyme]]
* [[Amino Acid Metabolism]]
* [[Genetic Disorder]]

[[Category:Enzymes]]
[[Category:Amino acids]]
[[Category:Metabolism]]
[[Category:Genetic disorders]]