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	Aldolase B		{{DISPLAYTITLE:Aldolase B}}

	Aldolase B is an enzyme that plays a crucial role in the metabolism of fructose. It is one of the three aldolase ~~isozymes found in vertebrates~~, the others being aldolase A and aldolase C. Aldolase B is primarily ~~expressed~~ in the liver, kidney, and ~~small~~ intestine.		== Aldolase B ==
			[[File:Aldolase_B_catalytic_mechanism.jpg\|thumb\|right\|300px\|Diagram of the catalytic mechanism of Aldolase B.]]
			'''Aldolase B''' is an enzyme that plays a crucial role in the [[metabolism]] of [[fructose]]. It is one of the three isoenzymes of [[aldolase]], the others being aldolase A and aldolase C. Aldolase B is primarily found in the [[liver]], [[kidney]], and [[intestine]].

	==Function==		== Function ==
	Aldolase B catalyzes the reversible cleavage of fructose-1-phosphate into dihydroxyacetone phosphate (DHAP) and glyceraldehyde. This reaction is a key step in the fructose metabolism ~~pathway~~, ~~allowing~~ the conversion of fructose into intermediates that can enter ~~glycolysis or gluconeogenesis~~.		Aldolase B catalyzes the reversible cleavage of [[fructose-1,6-bisphosphate]] and [[fructose-1-phosphate]] into [[dihydroxyacetone phosphate]] (DHAP) and [[glyceraldehyde]]. This reaction is a key step in both [[glycolysis]] and [[gluconeogenesis]]. In the context of fructose metabolism, aldolase B is essential for the conversion of fructose into intermediates that can enter the glycolytic pathway.

	==Structure==		== Structure ==
	Aldolase B is a homotetramer, meaning it is composed of four identical subunits. Each subunit contains a ~~catalytic site~~ that ~~binds to the substrate, fructose-1-phosphate~~. The ~~enzyme's~~ active site ~~includes~~ a lysine residue that forms a Schiff base with the substrate, facilitating the cleavage ~~reaction~~.		Aldolase B is a homotetramer, meaning it is composed of four identical subunits. Each subunit contains a [[TIM barrel]] structure, which is a common motif in enzymes that catalyze reactions involving sugar phosphates. The active site of aldolase B contains a [[lysine]] residue that forms a [[Schiff base]] with the substrate, facilitating the cleavage of the carbon-carbon bond.

	==~~Catalytic Mechanism~~==		== Clinical significance ==
	~~The catalytic mechanism~~ of aldolase B ~~involves the formation of~~ a ~~Schiff base intermediate between the enzyme and the substrate~~. ~~The lysine residue in~~ the ~~active site forms a covalent bond with the carbonyl group~~ of fructose-1-phosphate, ~~creating an imine~~. ~~This intermediate is then cleaved~~ to ~~produce dihydroxyacetone phosphate and glyceraldehyde~~.		Deficiency of aldolase B leads to a condition known as [[hereditary fructose intolerance]] (HFI). This is an [[autosomal recessive]] disorder characterized by the accumulation of fructose-1-phosphate in the liver, leading to [[hypoglycemia]], [[jaundice]], and [[hepatomegaly]]. Patients with HFI must avoid dietary fructose, sucrose, and sorbitol to prevent symptoms.

	~~[[File:Aldolase_B_catalytic_mechanism.jpg\|thumb\|right\|300px\|The catalytic mechanism of aldolase B.]]~~		== Related pages ==

	~~==Clinical Significance==~~
	Deficiency of aldolase B is associated with hereditary fructose intolerance (HFI), a genetic disorder that results in the accumulation of fructose-1-phosphate in the liver, leading to hypoglycemia, jaundice, and liver damage. Individuals with HFI must avoid dietary fructose to prevent symptoms.

	~~==Related Enzymes==~~
	* [[Aldolase A]]
	* [[Aldolase C]]

	==Related ~~Pages~~==
	* [[Fructose metabolism]]		* [[Fructose metabolism]]
	* [[Glycolysis]]		* [[Glycolysis]]
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	[[Category:Enzymes]]		[[Category:Enzymes]]
	[[Category:Metabolism]]		[[Category:Metabolism]]
	[[Category:~~EC 4.1.2~~]]		[[Category:Genetic disorders]]

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Aldolase B

Aldolase B is an enzyme that plays a crucial role in the metabolism of fructose. It is one of the three aldolase isozymes found in vertebrates, the others being aldolase A and aldolase C. Aldolase B is primarily expressed in the liver, kidney, and small intestine.

==Function==
Aldolase B catalyzes the reversible cleavage of fructose-1-phosphate into dihydroxyacetone phosphate (DHAP) and glyceraldehyde. This reaction is a key step in the fructose metabolism pathway, allowing the conversion of fructose into intermediates that can enter glycolysis or gluconeogenesis.

==Structure==
Aldolase B is a homotetramer, meaning it is composed of four identical subunits. Each subunit contains a catalytic site that binds to the substrate, fructose-1-phosphate. The enzyme's active site includes a lysine residue that forms a Schiff base with the substrate, facilitating the cleavage reaction.

==Catalytic Mechanism==
The catalytic mechanism of aldolase B involves the formation of a Schiff base intermediate between the enzyme and the substrate. The lysine residue in the active site forms a covalent bond with the carbonyl group of fructose-1-phosphate, creating an imine. This intermediate is then cleaved to produce dihydroxyacetone phosphate and glyceraldehyde.

[[File:Aldolase_B_catalytic_mechanism.jpg|thumb|right|300px|The catalytic mechanism of aldolase B.]]

==Clinical Significance==
Deficiency of aldolase B is associated with hereditary fructose intolerance (HFI), a genetic disorder that results in the accumulation of fructose-1-phosphate in the liver, leading to hypoglycemia, jaundice, and liver damage. Individuals with HFI must avoid dietary fructose to prevent symptoms.

==Related Enzymes==
* [[Aldolase A]]
* [[Aldolase C]]

==Related Pages==
* [[Fructose metabolism]]
* [[Glycolysis]]
* [[Gluconeogenesis]]
* [[Hereditary fructose intolerance]]

[[Category:Enzymes]]
[[Category:Metabolism]]
[[Category:EC 4.1.2]]

Aldolase B - Revision history

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