For example, insulin is a protein hormone that helps to regulate blood glucose levels. These proteins are secreted by endocrine cells that act to control or regulate specific physiological processes, which include growth, development, metabolism, and reproduction. Some proteins function as chemical-signaling molecules called hormones. These biosynthetic enzymes include DNA Polymerase, which catalyzes the synthesis of new strands of the genetic material before cell division fatty acid synthetase, which the synthesis of new fatty acids for fat or membrane lipid formation and components of the ribosome, which catalyzes the formation of new polypeptides from amino acid monomers. These enzymes include amylase, which catalyzes the digestion carbohydrates in the mouth and small intestine pepsin, which catalyzes the digestion of proteins in the stomach lipase, which catalyzes reactions need to emulsify fats in the small intestine and trypsin, which catalyzes the further digestion of proteins in the small intestine.Įnzymes are also essential for biosynthesis: the process of making new, complex molecules from the smaller subunits that are provided to or generated by the cell. Anabolic enzymes: enzymes that build more complex molecules from their substratesĮnzymes are essential for digestion: the process of breaking larger food molecules down into subunits small enough to diffuse through a cell membrane and to be used by the cell.Catabolic enzymes: enzymes that break down their substrate.There are two basic classes of enzymes:Įnzyme reaction: A catabolic enzyme reaction showing the substrate matching the exact shape of the active site. By placing the substrate into a specific shape and microenvironment in the active site, the enzyme encourages the chemical reaction to occur. When the substrate binds to its active site at the enzyme, the enzyme may help in its breakdown, rearrangement, or synthesis. The location where substrates bind to or interact with the enzyme is known as the active site, because that is the site where the chemistry occurs. The substrates are the reactants that undergo the chemical reaction catalyzed by the enzyme. Without enzymes, most physiological processes would proceed so slowly (or not at all) that life could not exist.īecause form determines function, each enzyme is specific to its substrates. These enzymes are essential for chemical processes like digestion and cellular metabolism. EnzymesĮnzymes are proteins that catalyze biochemical reactions, which otherwise would not take place.

Small changes in the amino acid sequence of a protein can cause devastating genetic diseases such as Huntington’s disease or sickle cell anemia. You probably look similar to your family members because you share similar proteins, but you look different from strangers because the proteins in your eyes, hair, and the rest of your body are different.īecause form determines function, any slight change to a protein’s shape may cause the protein to become dysfunctional. For example, hemoglobin is a globular protein, which means it folds into a compact globe-like structure, but collagen, found in our skin, is a fibrous protein, which means it folds into a long extended fiber-like chain. Proteins have different shapes and molecular weights, depending on the amino acid sequence. For instance, the blood protein hemogobin is made up of four polypeptide chains, each of which also contains a heme molecule, which is ring structure with an iron atom in its center. Sometimes non-polypeptide groups are also required in the final protein. Other times they combine with additional polypeptide chains to form the final protein structure. Sometimes these folded polypeptide chains are functional by themselves. These amino acids are covalently attached to one another to form long linear chains called polypeptides, which then fold into a specific three-dimensional shape. Proteins (a polymer) are macromolecules composed of amino acid subunits (the monomers ). The proteins’ α and β subunits are in red and blue, and the iron-containing heme groups in green. Human Hemoglobin: Structure of human hemoglobin.

Polar peptide backbone of amino acids