Enzyme Parts List:
The activity of an enzyme depends, at the minimum, on a specific
protein chain. In many cases, the enzyme consists of the protein
and a combination of one or more parts called cofactors. This
enzyme complex is usually simply referred to simply as the enzyme.
Apoenzyme: The polypeptide or protein part of the enzyme
is called the apoenzyme and may be inactive in its original
synthesized structure. The inactive form of the apoenzyme is
known as a proenzyme or zymogen. The proenzyme may contain
several extra amino acids in the protein which are removed, and
allows the final specific tertiary structure to be formed before
it is activated as an apoenzyme.
Cofactors: A cofactor is a non-protein substance which
may be organic, and called a coenzyme. The coenzyme is
often derived from a vitamin with specific examples discussed
Another type of cofactor is an inorganic metal ion called
a metal ion activator. The inorganic metal ions may be
bonded through coordinate covalent bonds. The major reason for
the nutritional requirement for minerals is to supply such metal
ions as Zn+2, Mg+2, Mn+2, Fe+2,
Cu+2, K+1, and Na+1 for use
in enzymes as cofactors.
Final Enzyme: The type of association between the cofactor
and the apoenzymes varies. In some cases, the bonds are rather
loose and both come together only during the course of a reaction.
In other cases, they are firmly bound together by covalent bonds.
The activating role of a cofactor is to either: activate the
protein by changing its geometric shape, or by actually participating
in the overall reaction.
The overall enzyme contains a specific geometric shape called
the active site where the reaction takes place. The molecule
acted upon is called the substrate.
Carboxypeptidase - Chime
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QUES: Using a diagram and in your own words, describe the various
parts of the enzyme, i.e. What is an enzyme?
|Quiz: Inactive protein enzyme?
|Organic nonprotein part of enzyme?
| Protein part of enzyme?