What are enzymes?

Enzymes are proteins. They are found everywhere in nature. For example, people and animals use enzymes to digest food.

The first use of enzymes occurred over 5000 years ago, when people stored milk in animal stomachs. The stomachs have enzymes, called “rennet,” that turn milk into cheese.
This is a good example of how enzymes work as catalysts, which means that they speed up biological reactions.
Novozymes’ customers use enzymes to replace harsh chemicals and improve a wide variety of industrial processes, for example in the manufacture of sugar, margarine, beer, yogurt, concrete, leather, textiles and ethanol, where the enzymes are not part of the end-product. Enzymes are also used directly in products such as laundry detergents, where they help remove stains and enable low-temperature washing.

Want to know more about enzymes? Read on.
Every enzyme has a specific function and no side effects
One of the unique things about enzymes is that they have one function and one function only. Only when the right enzyme finds the right substrate can the biochemical reaction occur; it works like a key in a lock.
This precise correlation between enzyme and substrate means that you never have to worry about side effects when enzymes are added to an industrial process. For instance, when enzymes transform starch into sugar, you can be sure that that is all that will happen. No other material or process will be altered or affected. In contrast, chemicals are non-specific and will do their thing to whatever they come across. So when you are using chemicals as a catalyst, you have to put up with a lot of side effects. 
Enzymes are stable and work in mild conditions
Enzymes work at low temperature and moderate pH, and are far more stable catalysts than other chemicals or biological molecules. For this reason enzymes are the most environmentally-friendly solution for industrial manufacturing.
Enzymes are not living organisms; they are simply biological molecules. They do not therefore live or die. They just keep on working until they are dissolved, usually by other enzymes.
That enzymes are catalysts also means that they do not become part of the final product of the biochemical reaction which they are catalyzing. When the biochemical reaction is over, the product of the reaction leaves the enzyme. The enzyme is then ready to effect the same reaction on another molecule again and again. Given the right conditions, the enzyme can go on and on for as long as needed. In some production processes, this lowers costs. 
Enzymes are biodegradable and environmentally friendly
Most manufacturing produces industrial waste that can present a threat to nature if it includes chemicals. Enzymes can usually do the same job cheaper and do not threaten the environment.
Enzymes are fully biodegradable. When industrial enzymes leave a production plant with the waste water, the retired enzymes do not last long in the surrounding environment. Nature has many microorganisms that easily break down enzymes into single amino acids, which are used to build up life around us.
The fact that enzymes create no hazardous waste makes them the most environmentally-friendly solution for industrial manufacturing.
All enzymes are proteins, but not all proteins are enzymes
Proteins are the building blocks of all living organisms. Humans, animals, plants and microorganisms are all made up of proteins.
Every part of the human body is built of proteins. Proteins constitute about 80% of the dry weight of muscle, 70% of the dry weight of skin and 90% of the dry weight of blood.
There are many different kinds of proteins, which can basically be split into two groups. The first group covers the structural proteins, which are the main constituents of our bodies. Well-known structural proteins are collagen, which is the protein of bones, tendons and ligaments, and keratin, the protein of nails, hair and feathers. The second large group of proteins covers the biologically-active proteins. Most of these catalyze biochemical reactions in cells. These are enzymes, the heart of Novozymes' business.
Enzymes consist of long strings of amino acids
Like all other proteins, enzymes are made of amino acids. Each enzyme is made of between a hundred and up to a million amino acids placed like pearls on a string. Each amino acid is bonded to the next by chemical bonds. Each enzyme has its own unique sequence of amino acids, which is determined by the genes in the cells.
The vast majority of enzymes are made of only 20 different kinds of amino acid. The structure and function of the enzyme is determined by the order of the amino acids.
Enzymes have a three-dimensional structure
Enzymes consist of millions of amino acids placed one after the other like pearls on a long string, but most enzymes do not look like a long string. In most enzymes, the string is coiled and folded thousands of times to form a highly complex three-dimensional structure, which is unique to each enzyme. It is the chemical interactions between the amino acids that force the enzymes into their three-dimensional structure, which is held together by the many different links between the different amino acids.
The arrangement of amino acids determines the enzyme's function
It is the unique three-dimensional structure of each enzyme that that determines the function of the enzyme. Even slight changes in the sequence of the amino acids on the string have a huge impact on the structure and function of the protein. With just one or perhaps a few amino acids replaced or switched, an enzyme may not only look different, but also act differently and convert to working on other biological molecules or treating them differently.
Enzymes have active sites that make them highly specific
Enzymes are large molecules with hundreds of amino acids, but only a small part of the enzyme participates in the catalysis of biochemical reactions. This is called the active site. The three-dimensional structure of the enzyme determines the appearance of the active site. The active site precisely accommodates the shape of the biological substrate. The enzyme and substrate fit together like a key in a lock, and only substrates with the right shape will be transformed by the enzyme. This is what makes enzymes specific in their action.