What is a Protease?
Proteases are basically proteins that break down other proteins. They
cleave the peptide bonds that link amino acids together. Proteases also
have many functions. Proteases such as pepsin and trypsin break down proteins
in food so that it can be absorbed into the blood for further metabolism.
Certain proteases destroy harmful proteins. For example white cells use
these proteases to break down bacteria and parasites. There are also many
biological and regulatory functions of the proteases.
Role of Protease in HIV
Since viruses are so small they must make maximum use of the minimal
genetic information that they have. HIV does this by making a long polypeptide
chains that contains many proteins. These protein precurser, Gag and Gag
Pol must be cleaved by protease at 9 specific points in order to produce
functional proteins. The gag precurser will eventually give rise to structural
proteins and pol precurser will give rise to enzymes such as reverse transcriptase,
integrase, and protease. Thus, an HIV specific protease is necessary for
the the HIV to make more functional viruses. The HIV protease is not found
in mammalian cells. The HIV protease is unique in that it can cleave between
a phenylalanine and tyrosine or proline. To look at the reaction click
is a very important fact because no human enzyme can cleave between either
tyrosine or phenyalanine and proline. For more information on the genetics
of HIV click here.
The HIV Protease is an enzyme with two symmetrical subunits. The active
site is located where the two subunits meet. HIV proteases are aspartic
acid proteases and thus, aspartate 25 plays a key role in binding the substrate.
a closer look at the active site click on the image.
the HIV Protease
These are the two products from HIV protease hydrolysis
Table of Contents
HIV Protease Inhibitor