Classes of Enzymes

Basics Introduction to Classes of Enzymes

Every enzyme shares some common properties - these are proteins that speed up or regulate the rate of specific chemical reactions without altering the product or being consumed in the process. The six main classes of enzymes, are:

• Oxidoreductases
• Transferases
• Hydrolases
• Lyases
• Isomerases
• Ligases

Each class is further divided into subclasses, sub-subclasses, and individual enzymes. Moving from class to subclass to sub-subclass narrows down the reaction type that an enzyme can catalyze. For instance, the enzyme hexokinase is classified as

2.7.1.1 

According to the Enzyme Commission (EC) number

2.7.1.1

, the first digit indicates that it's a member of the transferase class, the second digit signifies that it transfers phosphate groups, and the third digit signifies that the phosphate group is transferred to an alcohol group.

Function and Importance of Enzymes in Organic Chemistry

Enzymes are crucial for various chemical reactions in the body. They act as organic catalysts that alter the rate of reactions without participating in the reactions themselves. The importance of enzymes in organic chemistry extends beyond biology. Enzymes are increasingly used in the chemical industry for the production of fine chemicals and pharmaceuticals. Enzymes also play a crucial role in research and diagnostics. They help in the detection and diagnosis of diseases such as cancer and heart disease. Furthermore, enzymes are essential in the DNA replication process, a key step in cell division and growth. In organic chemistry, enzymes can catalyze a broad variety of chemical reactions including the breaking and making of covalent bonds. The reaction rate can increase by a factor of a million because of the catalyst function of the enzymes, making them a crucial subject to understand in the field of chemistry.

How Many Classes of Enzymes are there?

In the world of biochemistry, enzymes are broadly divided into six primary classes. Each one of these classes represents a distinct category of enzymes that carry out specific types of chemical reactions.

The 6 Classes of Enzymes Defined

Every class of enzymes exercises specific functions. Without further ado, let's delve into these crucial classes:

• Oxidoreductases: These enzymes carry out redox reactions where they transfer electrons from a donor molecule \( (reducing agent) \) to an acceptor molecule \( (oxidizing agent) \).
• Transferases: As the name suggests, these enzymes transfer a functional group \( (e.g., a phosphate or amino group) \) from one molecule to another.
• Hydrolases: They catalyze hydrolysis reactions \( the breaking of a compound into two parts through the addition of water \).
• Lyases: They catalyze the breaking of various sorts of chemical bonds by means other than by oxidation or hydrolysis, often forming a double bond or a new ring structure.
• Isomerases: These enzymes are responsible for catalyzing isomerization changes within a single molecule.
• Ligases: They join two molecules together and therein, they catalyze the reaction with the accompanying breakage of a pyrophosphate bond in ATP or a similar compound.

Remember that these classes offer categorical divisions depending on the type of reaction the enzyme carries out. Each class has further subclasses that indicate more specifics about the function.

Breakdown of Each Class of Enzymes

Let's have a closer look at each enzyme class using a table: Using the example above, the first digit in the EC number represents the enzyme class. The second digit signifies the subclasses within that class, while digits three and four give more specific detail about the enzyme's function and the reaction it carries out.

Distinction between Class and Family of Enzymes

But what's the difference between a class and a family of enzymes? While the terms are often interchangeably used, there is some distinction. Class refers to the categorisation of enzymes based on the type of reaction they catalyse, as explained above. An enzyme class, therefore, represents enzymes carrying out similar reactions. Family, on the other hand, focuses more on the structure and evolutionary relationship of enzymes. Enzymes within the same family share similar amino acid sequences and structural features. They've likely evolved from common ancestral genes, despite the different reactions they might catalyse. For instance, serine proteases comprise an enzyme family, having a common catalytic mechanism involving a serine residue. However, they are spread across different enzyme classes , reflecting their diverse roles in biological systems. So, understanding both enzyme families and classes will help you grasp the complexity and diversity of enzymes in biochemistry. They offer a view from two perspectives - one centered on function (class) and the other centered on form and evolution (family).

Amaylase Belongs to Which Class of Enzyme?

Amylase is a type of enzyme that falls under the category of Hydrolases. Its primary mechanism is to speed up the process of hydrolysis, specifically the breakdown of starch into sugars. Amylase, like other enzymes, performs an essential role in biology and chemistry, acting as a catalyst to accelerate specific biochemical reactions in various organisms.

Characteristics of Amylase in Enzyme Classification

Amylase is part of the hydrolase class of enzymes as per its last classification. Like other hydrolases, the primary function of amylase is to perform hydrolysis, i.e., reactions that involve breaking bonds between molecules by the addition of water (\(H_2O\)). Key to this function is the ability of amylase to initiate the decomposition of starch into glucose and maltose, making it an integral part of carbohydrate metabolism in many organisms. Outlined below are important specifics denoting the classification of amylase:

Class:      Hydrolases (Enzyme Class 3)
Subclass:   2 (Hydrolases acting on glycosyl compounds)
EC Number:  3.2.1.1

However, it's important to note that there are several subclasses of amylase, each with slightly different characteristics but all still hydrolases. For instance, \( \alpha \)-amylase, \( \beta \)-amylase, and glucoamylase are subtypes of amylase that differ primarily in terms of how they break up the carbohydrate molecule. Being a hydrolase, amylase has an optimal pH which ranges between 5.6 and 6.9, being most effective at pH 7. Understanding these attributes is crucial for aspiring chemists and biologists, as they play a significant role in biochemical reactions.

Role and Function of Amylase

Amylase plays a pivotal role in our physiology, specifically in the digestive system. It initiates the digestion of dietary carbohydrates, starting from the mouth where it is present in saliva, all the way down to the intestines. For instance, salivary amylase, a type of \( \alpha \)-amylase secreted by the salivary glands, kick-starts carbohydrate digestion by breaking down dietary starch into smaller polysaccharides and maltose, while pancreatic amylase (also an \( \alpha \)-amylase but excreted by the pancreas into the small intestine) continues this process in the gut. A primary role of amylase is to convert polysaccharides into smaller, absorbable molecules. Broadly, the hydrolysis of starch by amylase means converting large, insoluble starch molecules into soluble starch, dextrines, and sugars. For example, starch (\(C_6H_{10}O_5)_n\) when hydrolyzed by amylase, results in the formation of a simpler compound - maltose (\(C_{12}H_{22}O_{11}\)). \[ (C_6H_{10}O_5)_n + nH_2O \rightarrow nC_{12}H_{22}O_{11} \] In our bodies, the amylase-driven breakdown of starch into smaller sugars and subsequently into glucose, provides us with energy and supports numerous physiological processes. Further, the presence and level of amylase in the blood can assist with diagnosing certain conditions such as pancreatitis, indicating the enzyme's role in medical diagnostics. Understanding the role of enzymes like amylase uncovers the importance of biochemical reactions in everyday life, offering a fascinating diversion into the world of biology and chemistry.

Classes of Enzymes and Examples

The wide diversity of enzymes is organised into specific classes of enzymes based on the role they play in chemical reactions. Here, let's take a closer look at real-world examples of each class.

Real-World Examples for Each Class of Enzymes

From digestion to DNA replication, enzymes play a fundamental role in facilitating chemical reactions within living organisms. Here are some real-world examples of enzymes from each class: Investigating these examples reveals a marvellous variety of reactions for which nature has evolved these specialised biocatalysts. As enzymes speed up chemical reactions without being consumed themselves, they're crucial in determining the rate and efficiency of biochemical processes.

How Different Classes of Enzymes Interact in Chemical Reactions

Biochemical reactions in a living cell do not occur in isolation but are part of an intricately balanced network of metabolic pathways, where different classes of enzymes work in concert. Consider the process of carbohydrate metabolism: In glycolysis, hexokinase (a Transferase) phosphorylates glucose to glucose-6-phosphate. Phosphoglucose isomerase (an Isomerase) then converts glucose-6-phosphate to fructose-6-phosphate. Fructose-6-phosphate is further phosphorylated by phosphofructokinase (another Transferase), forming fructose-1,6-bisphosphate. This compound is split into two three-carbon sugars, catalysed by aldolase and triosephosphate isomerase (both Lyases), which are then oxidised and converted into pyruvate, involving several enzymes from the Oxidoreductase and Transferase classes. Alongside glycolysis, several other pathways, including gluconeogenesis, pentose phosphate pathway, and the citric acid cycle, share mutual intermediate compounds and the involvement of various enzymes classes, thus highlighting the elaborate interaction and collaboration of different enzyme classes. Also, situations may arise where simultaneous reactions involving multiple classes of enzymes occur. For example, during DNA replication, DNA polymerases (Transferases) synthesise new DNA strands, DNA ligases (Ligases) seal the gaps between DNA fragments, and DNA helicases (Hydrolases) unwind the double-stranded DNA helix. In these meticulously coordinated reactions, the different enzyme classes interact constructively within the context of their specialised functions, like the various instruments playing together harmoniously in an orchestra, each adding its unique contribution to the collective effect. Understanding these interactive dynamics between various enzyme classes illuminates how the cell accomplishes an intricate concert of biochemical tasks to aid growth, development, and survival.

Classes of Restriction Enzymes

Enzymes are involved in numerous biological processes, from digestion to DNA repair. One important category within this diverse group includes restriction enzymes, also known as restriction endonucleases. These enzymes are instrumental in the DNA modification and manipulation processes central to molecular biology.

Understanding Classes of Restriction Enzymes in Molecular Biology

Restriction enzymes, known for their ability to cut DNA at specific sites, are a crucial tool in molecular biology. They are usually classified into four primary classes (Type I, II, III, and IV), each with characteristic properties and mechanisms of action. On the other hand, While, Lastly, The practical function and cut-site of each class is summarised in the following table:

The unique properties of each class of restriction enzymes underline their individual strengths and applicability within molecular biology practice.

Practical Use of Restriction Enzymes in DNA Manipulation

In the realm of DNA manipulation, the ability of restriction enzymes to cut DNA at specific sites ensures their pivotal roles in both research and applied sciences. For instance, gene cloning - the process of producing identical genes - relies on restriction enzymes. By using these enzymes, scientists can isolate and incise a specific gene of interest from a DNA molecule. This gene can then be spliced into a circular piece of DNA called a plasmid, forming a recombinant DNA molecule that can be introduced into a bacterium for copying, thus creating multiple copies of a single gene. Genome mapping also heavily relies on restriction enzymes. Map-based cloning involves using restriction enzymes to cut DNA into manageable fragments, which can subsequently be sequenced or analysed in other ways. The spectrum of fragments, or restriction map, can provide useful information about the size and sequence of the original DNA molecule. Restriction Fragment Length Polymorphism (RFLP) is a technique used to exploit variations in DNA sequences. If two organisms differ in the distance between sites of cleavage of a specific restriction enzyme in a certain region of the genome, the length of the fragments produced will differ during gel electrophoresis. This method is commonly used in genetic fingerprinting, paternity testing, and criminal forensics. Through their ability to fragment genomic DNA at predictable sites, restriction enzymes have revolutionised molecular biology. Today, their use extends far beyond the mentioned applications, facilitating pioneering work in gene editing and recombinant DNA technology, among many others.