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{{Short description|Compounds in biochemical reactions}}
{{More citations needed|date=March 2024}}
'''Metabolic intermediates''' are [[Molecule|compounds]] produced during the conversion of [[Substrate (chemistry)|substrates]] (starting molecules) into [[Product (chemistry)|final products]] in [[Biochemical reaction|biochemical reactions]] within [[Cell (biology)|cells]].<ref>{{Cite journal |last1=Muchowska |first1=Kamila B. |last2=Varma |first2=Sreejith J. |last3=Moran |first3=Joseph |date=May 2019 |title=Synthesis and breakdown of universal metabolic precursors promoted by iron |journal=Nature |language=en |volume=569 |issue=7754 |pages=104–107 |doi=10.1038/s41586-019-1151-1 |issn=1476-4687 |pmc=6517266 |pmid=31043728|bibcode=2019Natur.569..104M }}</ref>

Although these intermediates are of relatively minor direct importance to cellular function, they can play important roles in the [[allosteric]] regulation of [[enzyme]]s, [[glycolysis]], the [[citric acid cycle]], and [[amino acid synthesis]].

[[Metabolic pathway|Metabolic pathways]] consist of a series of enzymatically catalyzed reactions where each step transforms a [[Substrate (chemistry)|substrate]] into a [[Product (chemistry)|product]] that serves as the [[Substrate (chemistry)|substrate]] for the next [[Chemical reaction|reaction]]. Metabolic intermediates are compounds that form during these steps, and they are neither the [[Substrate (chemistry)|starting substrate]] nor the [[Product (chemistry)|final product]] of the pathway. These intermediates are crucial because they allow for regulation, energy storage, and extraction of [[chemical energy]] in a controlled manner.<ref>{{Cite book |last=Voet |first=Donald |title=Biochemistry |last2=Voet |first2=Judith G. |year=2011 |publisher=Wiley |isbn=978-0-470-57095-1 |edition=4th |location=Hoboken, NJ }}</ref>

== Types of Metabolic Intermediates ==
Metabolic intermediates can belong to different biochemical classes based on the type of [[Metabolic pathway|pathway]] they are involved in. Some examples include:<ref>{{Cite book |title=Biochemistry |year=2015 |publisher=W.H. Freeman/Macmillan |isbn=978-1-4641-2610-9 |editor-last=Berg |editor-first=Jeremy M. |edition=8th |location=New York, NY |editor-last2=Tymoczko |editor-first2=John L. |editor-last3=Gatto |editor-first3=Gregory J. |editor-last4=Stryer |editor-first4=Lubert }}</ref>

* '''Carbohydrate intermediates''': In carbohydrate metabolism, intermediates such as [[Glucose 6-phosphate|glucose-6-phosphate]] and [[Fructose 1,6-bisphosphate|fructose-1,6-bisphosphate]] appear during [[glycolysis]] and [[gluconeogenesis]].
* '''Amino acid intermediates''': During [[Amino acid synthesis|amino acid biosynthesis]] or [[Amino acid degradation|degradation]], intermediates such as [[2-oxoglutarate]], [[pyruvate]], or [[oxaloacetate]] are produced. These intermediates also link to the [[citric acid cycle]].
* '''Lipid intermediates''': [[Fatty acid metabolism]] involves intermediates like [[acyl-CoA]] derivatives during [[β-oxidation]] or [[fatty acid synthesis]].
* '''Nucleotide intermediates''': The metabolism of [[Nucleotide|nucleotides]], the building blocks of [[DNA]] and [[RNA]], includes intermediates like [[inosine monophosphate]] (IMP), which is part of [[purine biosynthesis]].

== Clinical significance ==
Some can be useful in measuring rates of metabolic processes (for example, [[3,4-dihydroxyphenylacetic acid]] or [[3-aminoisobutyrate]]).

Because they can represent unnatural points of entry into natural metabolic pathways, some (such as [[AICA ribonucleotide]]) are of interest to researchers in developing new therapies.

==See also==
* [[Metabolism]]

== References ==
{{reflist}}

{{Fructose and galactose metabolic intermediates}}
{{Glycogenesis and glycogenolysis metabolic intermediates}}
{{Pentose phosphate pathway intermediates}}
{{Fatty-acid metabolism intermediates}}
{{Sphingolipids}}
{{Cholesterol metabolism intermediates}}
{{Amino acid metabolism intermediates}}
{{Nucleotide metabolism intermediates}}
{{Neurotransmitter metabolism intermediates}}
{{Heme metabolism intermediates}}
{{Thyroid hormone intermediates}}

[[Category:Metabolism]]

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