Country: United States
Date: July 2008
Cannot find a definite answer to the following
question: Explain what is meant by biological activity of a
The biological function of a protein is either structural (collagen,
for example), carrier (hemoglobin, for example), enzymatic (trypsin,
for example), regulatory (receptor proteins and insulin, for example),
mechanical (myosin, for example). Google "functions of proteins" for
Ron Baker, Ph.D.
In general, proteins are designed to 'attach' to biological molecules. They
might attach to each other to form structural units in the cell, or they
might attach to other biological molecules to do specific tasks (such as
catalyze a chemical reaction). These functions are known as the protein's
A protein is like a long string that is folded around itself in a specific
way. If the protein comes unfolded or is folded in the wrong way, it may no
longer be able to perform its function. When this happens, we say it has
lost its biological activity. In the case of chemical reactions, you can
quantitatively measure how fast the reaction occurs, and measure a
quantitative biological activity (for example, to compare two proteins'
ability/speed to break down a sugar).
Some laboratory techniques that measure protein cannot tell if the protein
is active or not -- they can only tell if the protein is present or how much
there is. Thus, you may measure that protein is present in a sample, but if
the protein has been degraded in some way, you may not measure any
biological activity. That's why biologists make a distinction between amount
of protein and biological activity.
Hope this helps,
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Update: June 2012