What is Hydrolase?

Hydrolases are a type of enzyme that acts as a biochemical catalyst by breaking a chemical bond with water, resulting in the division of a larger molecule into smaller molecules. Esterase enzymes, such as lipases, phosphatases, glycosidases, peptidases, and nucleosidases, are examples of hydrolase enzymes. 

Because of their degradative properties, hydrolase enzymes are important for the human body. Lipases help break down fats, lipoproteins, and other large molecules into smaller molecules like fatty acids and glycerol in lipids. Fatty acids and other small molecules are used as a source of energy and for synthesis.

A hydrolase is a type of enzyme that catalyses the hydrolysis of a chemical bond in biochemistry. A hydrolase, for example, is an enzyme that catalyses the following reaction:

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This article will study acid hydrolases, glycoside hydrolase and examples of hydrolases in detail.

Acid Hydrolases

Acid hydrolases are enzymes that function best when the pH is acidic. It's most commonly found in lysosomes, which have an acidic interior. Acid hydrolases include nucleases, proteases, glycosidases, lipases, phosphatases, sulfatases, and phospholipases, and they make up the lysosome's approximately 50 degradative enzymes.

Example of Hydrolases:

  • Nucleases

  • Lipase: for example lysosomal acid lipase.

  • Proteases

  • Glycoside hydrolase

Glycoside Hydrolase

Hydrolysis of glycosidic bonds in complex sugars is catalysed by glycoside hydrolases (also known as glycosidases or glycosyl hydrolases). They are extremely common enzymes that play a variety of roles in nature, including cellulose (cellulase), hemicellulose (hemicellulose), and starch (amylase) degradation, antibacterial protection strategies (e.g., lysozyme), pathogenesis mechanisms (e.g., viral neuraminidases), and normal cellular function (e.g., trimming mannosidases involved in N-linked glycoprotein biosynthesis). Glycosidases, together with glycosyltransferases, are the key enzymes involved in the synthesis and breakage of glycosidic bonds.

Epoxide Hydrolase

Epoxide hydrolases (EHs), also known as epoxide hydratases, are enzymes that metabolise compounds containing an epoxide residue, converting it to two hydroxyl residues through a dihydroxylation reaction, resulting in diol products. EH activity can be found in a variety of enzymes. The structurally linked isozymes microsomal epoxide hydrolase (mEH), soluble epoxide hydrolase (sEH, epoxide hydrolase 2, EH2, or cytoplasmic epoxide hydrolase), and the more recently discovered but not yet well described functionally, epoxide hydrolase 3 (EH3) and epoxide hydrolase 4 (EH4).

Lysosomal Hydrolase

Lysosomal lipase is a type of lipase that works inside the cell, in the lysosomes. Lysosomal lipase's primary role is to hydrolyze lipids including triglycerides and cholesterol. These fats are carried around and degraded into free fatty acids. Lysosomal lipases work best in an acidic pH range, which is compatible with the lysosomal lumen environment. Only the lipids present in organelle membranes and extracellular lipids were thought to be hydrolyzed by these enzymes.

Serine Hydrolase

Serine hydrolases are one of the largest known enzyme groups, accounting for around 200 enzymes or 1% of the human proteome's genes. The presence of a nucleophilic serine in the active site, which is used for substrate hydrolysis, is a distinguishing feature of these enzymes. Via this serine, catalysis begins with the formation of an acyl-enzyme intermediate, followed by saponification of the intermediate by water/hydroxide and regeneration of the enzyme. The nucleophilic serine of these hydrolases, unlike other non-catalytic serines, is normally activated by a proton relay involving a catalytic triad consisting of the serine, an acidic residue (e.g. aspartate or glutamate), and a simple residue (usually histidine), though there are variations on this mechanism.

Cholesterol Ester Hydrolase

A sterol esterase is an enzyme that catalyses the chemical reaction in enzymology.

Sterol Ester + H2O     sterol + fatty acid

Thus, sterol ester and H2O are the enzyme's two substrates, while sterol and fatty acid are the enzyme's two products.

Bile Salt Hydrolase

Intestinal bacteria manufacture bile salt hydrolase (BSH), which catalyses the deconjugation of glyco- and Tauro-conjugated bile acids by hydrolyzing the amide bond and releasing free bile acids (e.g. cholic acid and chenodeoxycholic acid) and amino acids (glycine and taurine).

Soluble Epoxide Hydrolase

The EPHX2 gene encodes a bifunctional enzyme known as soluble epoxide hydrolase (sEH). The epoxide hydrolase family includes sEH. This enzyme binds to various epoxides and transforms them to the corresponding diols in the cytosol and peroxisomes. This protein also has lipid-phosphate phosphatase activity in another area. Familial hypercholesterolemia has been linked to mutations in the EPHX2 gene.

Alpha Beta Hydrolase

The alpha/beta hydrolase superfamily is a group of hydrolytic enzymes with a similar fold but different phylogenetic origins and catalytic functions. Each enzyme consists of an alpha/beta-sheet (rather than a barrel) with 8 beta strands linked by 6 alpha-helices at its centre. The enzymes are thought to have diverged from a common ancestor, maintaining no apparent sequence similarity but retaining the catalytic residues' structure. All of them have a catalytic triad, the components of which are carried on loops, the fold's most well-preserved structural features.

Nudix Hydrolase

Nudix hydrolases are a group of hydrolytic enzymes that can cleave nucleoside diphosphates linked to any moiety, hence their name. Nucleoside monophosphate (NMP) and X-P are the products of the reaction. With varying degrees of substrate specificity, nudix enzymes hydrolyze a broad variety of organic pyrophosphates, including nucleoside bi- and triphosphates, dinucleoside and diphosphoinositol polyphosphates, nucleotide sugars, and RNA caps. The Nudix superfamily of enzymes can be present in eukaryotes, bacteria, and archaea, among other species.

Bleomycin Hydrolase

Bleomycin hydrolase (BMH) is a cytoplasmic cysteine peptidase with a long evolutionary history. Hydrolysis of the reactive electrophile homocysteine thiolactone is its biological function. Another of its functions is metabolic inactivation of the glycopeptide bleomycin (BLM), which is an important component of cancer treatment regimens. The protein has the cysteine protease papain superfamily's characteristic active site residues.

Did You Know?

Acetylcholinesterase is one of the most common hydrolases (cholinesterase). Acetylcholine is a powerful neurotransmitter involved in voluntary muscle contraction. Nerve impulses pass through neurons to the synaptic cleft, where acetylcholine stored in vesicles is released, bringing the impulse through the synapse and propagating the nerve impulse to the postsynaptic neuron. After the nerve impulse has passed, cholinesterase, which hydrolyzes acetylcholine to choline and acetic acid, must interrupt the activity of the neurotransmitter molecules. Some harmful toxins, such as Clostridium botulinum exotoxin and saxitoxin, interact with cholinesterase, and many nerve agents, such as tabun and sarin, work by binding to cholinesterase.

FAQs (Frequently Asked Questions)

1. What are Lysosomal Hydrolases?

Ans: Proteases, nucleases, glycosidases, lipases, phospholipases, and phosphatases are all found in lysosomes, which are membranous bags containing hydrolytic enzymes. Acid hydrolases are hydrolytic enzymes that are most active in an acidic environment. Lysosomes break down phagocytosed content and worn-out cell pieces.

2. What are Some Examples of Hydrolytic Enzymes?

Ans: Cellulase, cellobiase, xylanase, and amylase are hydrolytic enzymes that transform carbohydrates into sugars, protease hydrolyzes proteins into amino acids, and lipase hydrolyzes lipids into glycerol and long-chain fatty acids (LCFA).

3. What is the Meaning of the Word Hydrolase in the Context of Digestive Enzymes?

Ans: Hydrolases are enzymes that catalyse the hydrolysis of macromolecular substances such as proteins, nucleic acids, starch, fats, phosphate esters, and other macromolecules. The hydrolysis is carried out by adding water to the mixture. This is how digestive enzymes function, which is why they're called hydrolases.