Proteins and enzymes

Structure and Function of Proteins

Proteins are crucial cell components that perform varied tasks.
Tissue repair, structural development, biochemical substances transport, and immunity roles are some crucial functions of proteins.
Amino acids, bonded together, form a polypeptide chain creating proteins.
Diverse types of proteins are manufactured by sequencing various amino acids differently.

Proteins have four structural levels: primary, secondary, tertiary, and quaternary.
Primary structure of proteins refers to the sequence of amino acids.
Secondary structure pertains to local folding patterns due to hydrogen bonds between backbone atoms, forming alpha-helices or beta-sheets.
Tertiary structure is the total three-dimensional shape of a protein resulting from the interactions of side chains like ionic bonds, hydrophobic interactions, and disulphide bridges.
Quaternary structure explains how different polypeptide chains assemble to form a functional protein complex.

Enzymes are a special type of proteins that act as biocatalysts to accelerate biochemical reactions in living organisms.
Enzymes enhance the reaction rates by decreasing the activation energy of reactions, enabling life crucial reactions at regular body temperature.

Each enzyme is specific to a certain substrate or reactant molecule.
The enzyme and substrate bind in a precise area on the enzyme known as the active site.
The Lock and Key Model or Active Site Theory suggests each enzyme has a distinctive shape allowing only one substrate to fit in.

Factors such as temperature, pH, and substrate concentration can influence enzyme activity.
Each enzyme has an optimum temperature and pH at which it functions most efficiently.
If the temperature and pH deviate from the optimum, the reaction rate reduces.
Increasing substrate concentration boosts the reaction rate till a saturation point. Beyond this, the rate remains constant due to all active sites being occupied.

Enzyme inhibitors are certain molecules that bind with enzymes and lower their activity.
Two main types of inhibitors exist: competitive and non-competitive.
Competitive inhibitors fight with the substrate for the active site on the enzyme, while non-competitive inhibitors bind to an alternate enzyme site, altering its shape and blocking substrate binding.