The relatioship of structure to funtion is one of the major themes in biology. Describe the structure of enzymes and then expliain how the function (catalysis) is related to structure. Aslo discuss some factors that may affect the activity of the enzyme and how they do so.
Enzymes are protein molecules that serve as catalysts in biological reactions. They play a crucial role in speeding up the rate of chemical reactions in living organisms. The structure of enzymes is highly complex and specific, allowing them to perform their function efficiently.
Enzymes consist of a long chain of amino acids that are folded and arranged in a particular three-dimensional shape. This shape is essential for the enzyme's activity and is determined by the sequence of amino acids in the protein chain. The structure of an enzyme can be divided into two main components: the active site and the allosteric sites.
The active site is a small and specific region of the enzyme where the substrate, the molecule that the enzyme acts upon, binds. The active site has a shape that matches the shape of the substrate, forming an enzyme-substrate complex. This complex allows the enzyme to catalyze the chemical reaction, facilitating the conversion of the substrate(s) into the product(s).
The structure of the active site is highly complementary to the substrate, resembling a lock and key mechanism. This specificity ensures that enzymes can selectively interact with their corresponding substrates, increasing the efficiency of catalysis. Changes in the structure of the active site can significantly affect the enzyme's function. For example, if there is a mutation or alteration in the amino acid sequence that forms the active site, the enzyme may no longer be able to bind to the substrate and catalyze the reaction.
In addition to the active site, enzymes may also have allosteric sites. These sites are distinct regions on the enzyme where molecules called allosteric regulators can bind. Allosteric regulators can either enhance or inhibit the enzyme's activity. When an allosteric regulator binds to the enzyme, it induces a conformational change in the enzyme's structure, which can either activate or deactivate the enzyme's catalytic function.
The activity of enzymes can also be influenced by several factors, including temperature, pH, substrate concentration, and the presence of inhibitors or activators. Temperature affects enzyme activity by altering the kinetic energy of molecules, specifically increasing the rate of collisions between the enzyme and the substrate. However, extremely high temperatures can denature the enzyme, causing it to lose its structure and function.
pH also plays a crucial role in enzyme activity. Each enzyme has an optimal pH level at which it functions most efficiently. Deviating from this optimal pH can disrupt the enzyme's structure, affecting its ability to bind with the substrate and catalyze the reaction.
Substrate concentration affects enzyme activity through a principle called saturation kinetics. Initially, as the substrate concentration increases, the enzyme activity also increases, as more substrate molecules are available to bind with the enzymes. However, there comes a point where all the enzyme molecules are occupied by the substrate, resulting in a maximum reaction rate, known as the enzyme's Vmax.
Finally, inhibitors and activators can modulate enzyme activity. Inhibitors are molecules that bind to the enzyme and inhibit its activity, either competitively (by binding to the active site) or non-competitively (by binding to an allosteric site). Activators are molecules that enhance the enzyme's activity, often by binding to an allosteric site and inducing a conformational change that increases the enzyme's affinity for the substrate.
Overall, the relationship between the structure and function of enzymes is critical for their catalytic activity. The precise structure of an enzyme, particularly its active site, allows it to interact specifically with the substrate, thus enabling catalysis. Any changes in the structure of the enzyme can affect its ability to bind to the substrate and catalyze the reaction. Additionally, various factors such as temperature, pH, substrate concentration, and regulatory molecules can influence the activity of enzymes. Understanding these factors and their effects on enzyme activity is essential in the study of biology.
Since this is not my area of expertise, I searched Google under the key words "enzymes structure function" to get these possible sources:
http://www.chemsoc.org/networks/learnnet/cfb/enzymes.htm
http://people.ku.edu/%7Ejbrown/enzyme.html
http://en.wikipedia.org/wiki/Enzyme
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search.
I hope this helps. Thanks for asking.