Name: enzyme helpers: metals, vitamins, and more
Uploaded: 2019-07-31T14:21:57.000Z
Duration: 1 min 27 s
Channel: JoVE

In many cases, enzymes require additional molecules&mdash;called cofactors&mdash;to function. These helper molecules can either be classified as metallic ions or organic, non-protein molecules.&nbsp;

For example, during the first step of glycolysis, the cofactor magnesium binds to ATP, tightening the bond between two of the phosphate groups. This action allows the last phosphate group to be more easily released by the enzyme hexokinase, transforming glucose into glucose 6-phosphate. Therefore, magnesium, as a cofactor, binds to and increases the efficiency of the ATP.&nbsp;

The other subset of cofactors&mdash;coenzymes&mdash;are organic compounds, usually derivatives of vitamins. &nbsp;

For instance, Vitamin C is an important coenzyme in the synthesis of the protein collagen. When a hydroxylase binds to collagen, Vitamin C facilitates the hydroxylation of residues on the collagen.&nbsp;With the help of Vitamin C, the hydroxylase promotes the change in the shape of the collagen to its final triple helical structure, which is essential to the maintenance of important body tissues.

cofactors and coenzymes

Cofactors and Coenzymes

Enzymes require additional components for proper function. There are two such classes of molecules: cofactors and coenzymes. Cofactors are metallic ions and coenzymes are non-protein organic molecules. Both of these types of helper molecule can be tightly bound to the enzyme or bound only when the substrate binds.

Cofactors are present in ~30% of mature proteins. They are frequently incorporated into an enzyme as it is folded and are involved in the enzyme&rsquo;s catalytic activity. Magnesium is an essential cofactor for over 300 enzymes in the human body, including DNA polymerase. In this case, the magnesium ion aids in the formation of the phosphodiester bond on the DNA backbone. Iron, copper, cobalt, and manganese are other common cofactors.

Many vitamins are coenzymes, as they are nonprotein, organic helper molecules for enzymes. For example, biotin&mdash;a type of B vitamin&mdash;is important in a variety of enzymes that transfer carbon dioxide from one molecule to another.&nbsp; Biotin, vitamin A and other vitamins must be ingested in our diet, as they cannot be made by human cells.

Enzymes require additional components for proper function. There are two such classes of molecules: cofactors and coenzymes. Cofactors are metallic ions ...

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enzyme helpers: metals, vitamins, and more

Enzyme helpers are needed for many enzymes to work properly. These helpers fall into two groups: cofactors and coenzymes. Cofactors are metallic ions, while coenzymes are non-protein organic molecules. Both can be tightly bound to an enzyme or attach only when the substrate binds.

Cofactors are common in mature proteins, appearing in about 30% of them. They are often added as the enzyme folds and help with catalytic activity. Magnesium is one important cofactor, and it is needed by more than 300 enzymes in the human body, including DNA polymerase. In DNA polymerase, magnesium helps form the phosphodiester bond in the DNA backbone. Iron, copper, cobalt, and manganese are other common cofactors.

Many coenzymes come from vitamins. These organic helper molecules assist enzymes during reactions. Biotin, which is a B vitamin, helps several enzymes move carbon dioxide from one molecule to another. Vitamin A and other vitamins must come from the diet because human cells cannot make them.

Enzyme Helpers: Metals, Vitamins, and More

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Enzyme helpers are needed for many enzymes to work properly. These helpers fall into two groups: cofactors and coenzymes. Cofactors are metallic ions, while coenzymes are non-protein organic molecules. Both can be tightly bound to an enzyme or attach only when the substrate binds. Cofactors are common in mature proteins, appearing in about 30% of them. They are often added as the enzyme folds and help with catalytic activity. Magnesium is one important cofactor, and it is needed by more than...

key terms and concepts

Learn how cofactors and coenzymes help enzymes work, from magnesium in DNA polymerase to biotin and other vitamin-based helpers.

Enzyme Helpers: Metals, Vitamins, and More | JoVE K12

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Enzyme Helpers: Metals, Vitamins, and More

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