A substrate is substance on which enzymes acts to covert into a product.
For many enzymes, there is only one substrate. But for most enzymes have two or even more substrates.
A substrate is very specific for an enzyme to catalyze the reaction.
What is a substrate role in enzyme reaction.
- An enzyme catalyzes a reaction only in the presence of a substrate.
- Increase in substrate concentration can enhance the reaction rate.
- But, the rate of reaction reaches peak when the enzyme is saturated by the substrate.
Examples of substrates:
1. Carbohydrates like glucose, sucrose, starch act a substrates for enzymes like salivary amylase, maltase
2. Amino acids, peptides, proteins act as substrates for enzymes trypsin, chymostrypsin etc. These proteins are found in grams, meat we eat.
3. Fatty acids act as substrate for lipase enzyme. Fats are obtained from food and by synthesis in the body.
4.Nucleic acids DNA and RNA are substrates for nuclease enzyme.
When substrate concentration is increased, the reaction rate is enhanced as there are more number of substrate molecules ready to undergo biochemical reaction in the presence of an enzyme. However, this is limited till the level of saturation of enzyme with the substrate. After saturation point, further increase in substrate concentration does not change the reaction rate as the enzyme molecules are saturated and they require time for dissociation of product from the enzyme. Hence, after saturation, further increase in substrate concentration would only lead to stable reaction kinetics.