Hydrolysis
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Hydrolysis (
Biological hydrolysis is the cleavage of biomolecules where a water molecule is consumed to effect the separation of a larger molecule into component parts. When a carbohydrate is broken into its component sugar molecules by hydrolysis (e.g., sucrose being broken down into glucose and fructose), this is recognized as saccharification.[2]
Hydrolysis reactions can be the reverse of a condensation reaction in which two molecules join into a larger one and eject a water molecule. Thus hydrolysis adds water to break down, whereas condensation builds up by removing water.[3]
Types
Usually hydrolysis is a chemical process in which a molecule of water is added to a substance. Sometimes this addition causes both the substance and water molecule to split into two parts. In such reactions, one fragment of the target molecule (or parent molecule) gains a hydrogen ion. It breaks a chemical bond in the compound.
Salts
A common kind of hydrolysis occurs when a
Esters and amides
Acid–base-catalysed hydrolyses are very common; one example is the hydrolysis of
Perhaps the oldest commercially practiced example of ester hydrolysis is saponification (formation of soap). It is the hydrolysis of a triglyceride (fat) with an aqueous base such as sodium hydroxide (NaOH). During the process, glycerol is formed, and the fatty acids react with the base, converting them to salts. These salts are called soaps, commonly used in households.
In addition, in living systems, most biochemical reactions (including ATP hydrolysis) take place during the catalysis of enzymes. The catalytic action of enzymes allows the hydrolysis of proteins, fats, oils, and carbohydrates. As an example, one may consider proteases (enzymes that aid digestion by causing hydrolysis of peptide bonds in proteins). They catalyze the hydrolysis of interior peptide bonds in peptide chains, as opposed to exopeptidases (another class of enzymes, that catalyze the hydrolysis of terminal peptide bonds, liberating one free amino acid at a time).
However, proteases do not catalyze the hydrolysis of all kinds of proteins. Their action is stereo-selective: Only proteins with a certain tertiary structure are targeted as some kind of orienting force is needed to place the amide group in the proper position for catalysis. The necessary contacts between an enzyme and its substrates (proteins) are created because the enzyme folds in such a way as to form a crevice into which the substrate fits; the crevice also contains the catalytic groups. Therefore, proteins that do not fit into the crevice will not undergo hydrolysis. This specificity preserves the integrity of other proteins such as hormones, and therefore the biological system continues to function normally.
Upon hydrolysis, an amide converts into a carboxylic acid and an amine or ammonia (which in the presence of acid are immediately converted to ammonium salts). One of the two oxygen groups on the carboxylic acid are derived from a water molecule and the amine (or ammonia) gains the hydrogen ion. The hydrolysis of peptides gives amino acids.
Many
ATP
Hydrolysis is related to
Secondly, the removal of a terminal diphosphate to yield adenosine monophosphate (AMP) and pyrophosphate. The latter usually undergoes further cleavage into its two constituent phosphates. This results in biosynthesis reactions, which usually occur in chains, that can be driven in the direction of synthesis when the phosphate bonds have undergone hydrolysis.
Polysaccharides
Monosaccharides can be linked together by glycosidic bonds, which can be cleaved by hydrolysis. Two, three, several or many monosaccharides thus linked form disaccharides, trisaccharides, oligosaccharides, or polysaccharides, respectively. Enzymes that hydrolyze glycosidic bonds are called "glycoside hydrolases" or "glycosidases".
The best-known disaccharide is
The hydrolysis of polysaccharides to soluble sugars can be recognized as
DNA
Hydrolysis of DNA occurs at a significant rate in vivo.[4] For example, it is estimated that in each human cell 2,000 to 10,000 DNA purine bases turn over every day due to hydrolytic depurination, and that this is largely counteracted by specific rapid DNA repair processes.[4] Hydrolytic DNA damages that fail to be accurately repaired may contribute to carcinogenesis and ageing.[4]
Metal aqua ions
Metal ions are
Thus the aqua
The
Hydrolysis may proceed beyond the first step, often with the formation of polynuclear species via the process of olation.[7] Some "exotic" species such as Sn3(OH)2+4[8] are well characterized. Hydrolysis tends to proceed as pH rises leading, in many cases, to the precipitation of a hydroxide such as Al(OH)3 or AlO(OH). These substances, major constituents of bauxite, are known as laterites and are formed by leaching from rocks of most of the ions other than aluminium and iron and subsequent hydrolysis of the remaining aluminium and iron.
Mechanism strategies
Acetals, imines, and enamines can be converted back into ketones by treatment with excess water under acid-catalyzed conditions: RO·OR−H3O−O; NR·H3O−O; RNR−H3O−O.[9]
Catalysis
Acidic hydrolysis
Acids catalyze hydrolysis of
Acid hydrolysis can be utilized in the pretreatment of cellulosic material, so as to cut the interchain linkages in hemicellulose and cellulose.[16]
Alkaline hydrolysis
Alkaline hydrolysis usually refers to types of
The reaction is often used to solubilize solid organic matter.
See also
References
- ^ a b "Definition of Saccharification". Merriam-Webster. Archived from the original on 7 January 2021. Retrieved 8 September 2020.
- ^ Steane, Richard. "Condensation and Hydrolysis". www.biotopics.co.uk. Archived from the original on 2020-11-27. Retrieved 2020-11-13.
- ^ a b c Lindahl T. Instability and decay of the primary structure of DNA. Nature. 1993 Apr 22;362(6422):709-15. doi: 10.1038/362709a0. PMID: 8469282
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- ^ US 5726046, Farone, William A. & Cuzens, John E., "Method of producing sugars using strong acid hydrolysis", published 1998-03-10, assigned to Arkenol Inc.
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- ^ "5.4: Hydrolysis Reactions". Chemistry LibreTexts. 2021-08-04. Retrieved 2023-10-07.
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