Question

Which of the following is an enzyme? (a) lipids (b) sucrose (c) emulsin (d) maltose

Short answer

(c) emulsin is an enzyme.

Step-by-step solution

Understand What an Enzyme Is

An enzyme is a protein that acts as a catalyst in biochemical reactions. It speeds up the reactions by lowering the activation energy needed for the reaction to occur.

Analyze Each Option

Identify whether each option could be an enzyme based on the definition of an enzyme as a protein catalyst. - (a) **Lipids**: These are fats, not enzymes, so they do not act as catalysts. - (b) **Sucrose**: This is a sugar, a carbohydrate, not a protein. - (c) **Emulsin**: This is a known enzyme, specifically a glycoside hydrolase enzyme. - (d) **Maltose**: This is another sugar, not a protein, and therefore not an enzyme.

Select the Enzyme

Based on the definitions and characteristics examined in Step 2, the only option that fits the criteria of being an enzyme is **(c) emulsin**.

Key concepts

Protein catalysts

Enzymes are special proteins that function as catalysts in biochemical reactions. What makes them unique is their ability to dramatically increase the rate of these reactions without being consumed in the process. Catalysts work by lowering the activation energy, which is the minimum amount of energy needed for a reaction to occur. This allows reactions that might otherwise be too slow or require too much energy to proceed under the conditions present in living organisms.
Enzymes are fundamental to life because they speed up reactions that are necessary for the survival of cells. They are highly efficient and can work on multiple molecules of substrate at the same time. This efficiency is due to their ability to form a temporary complex with the substrate, stabilizing the transition state and leading to faster product formation.

• Enzymes are specific to substrates, meaning that each enzyme only catalyzes specific reactions with specific molecules.
• They are essential for processes like digestion, metabolism, and DNA replication, among others.
• Despite catalyzing reactions, enzymes are not permanently altered or used up in the reaction.

Enzyme identification

Identifying an enzyme involves recognizing that it is a protein designed to catalyze a specific biochemical reaction. In the example provided, options were evaluated to determine which could be an enzyme based on their chemical nature and function.
To identify an enzyme, one must understand that:

• Enzymes are always proteins, so any molecule not primarily composed of amino acids cannot be an enzyme. This rules out options like lipids or carbohydrates.
• Many enzyme names end in "-ase," making it easier to spot them; however, this is not a strict rule as seen with the enzyme emulsin.
• Some enzymes are known by specific names that may not fit the typical naming convention. It's important to familiarize oneself with common enzyme names.

In practice, knowing the classifications and functions of potential enzymes helps in their identification. Textbooks and scientific resources can provide lists of known enzymes and their functions for reference.

Biochemical reactions

Biochemical reactions are chemical processes that occur within living organisms to maintain life. These reactions are usually complex and need to happen at substantial rates to meet the physiological demands of an organism. Enzymes play a critical role in facilitating such reactions.
Their role in these reactions includes:

• Serving as catalysts that increase reaction rates by lowering activation energy. Without enzymes, many biochemical reactions would be too slow to sustain life.
• Providing specificity, as each enzyme typically catalyzes only a specific reaction or set of reactions. This ensures the correct metabolic pathways are followed.
• Regulating metabolic pathways. By switching on or off, or by modulating their activity, enzymes help regulate the flow of biochemical pathways, ensuring balance depending on the needs of the organism at any given time.

Understanding biochemical reactions and the pivotal role enzymes play is crucial in fields such as biochemistry, medicine, and biotechnology. It allows scientists and professionals to manipulate these reactions for applications ranging from developing medication to improving industrial processes.