Biochemistry 305: Allosteric Inhibition

[liveonearth]

oligomeric enzyme = with multiple active sites in one multisubunit protein - subject to allosteric inhibition

substrate binding to one active site may increase or decrease the activity of other active sites (increase: like cooperativity in hemoglobin)

phosphofructokinase is an enzyme that adds a 2nd phosphate group to fructose
-a tetramer with 4 active sites
-this is step 3 of glycolysis, uses ATP
-allosteric inhibitor is phosphoenolpyruvate, a feedback inhibitor: when its concentration is high, it shuts down its own synthesis
-when inhibitor is present, sigmoidal curve of velocity graph means active sites are cooperative
-allosteric activator is ADP, signals need for more ATP

glycolysis = process of glucose degradation that yields ATP, very important energy source for nearly all cells

HIV
-causative agent of AIDS
= a 9 kb RNA genome embedded in a protein core that is in turn surrounded by an outer protin-lipid envelope
-HIV "particle"
-core contains vial enzymes and other proteins required for infectivity
-envelope proteins contact host cell-surface proteins cause virus to enter cell and RNA is uncoated
-RNA is transcribed into DNA by the action of the viral enzyme reverse transcriptase
-another viral enzyme, an integrase, integrates the resulting DNA into the host genome
-expression of viral genes produces 15 different proteins, some processed by a viral protease
-full production: new viral particles are assembled and bud off from host cell membrane

ATTACK HIV by attacking the enzymes with inhibitors