Enzymology Flashcards
enzyme
a protein molecule that accelerates a specific chemical reaction
active site
the region of an enzyme that binds the substrate during the reaction
substrate
the reactant(s) in an enzyme-catalysed reaction
lock and key model
ligand binding sites are rigid & complementary to shape of ligand
induced fit model
flexible interaction between the ligand & active site; ligand induces a conformational change in active site
Cahn-Ingold-Prelog (CIP) priority rules
atoms of higher atomic number bonded to a chiral centre are ranked above those of lower atomic number
oxidoreductases
Transfer of H & O atoms or electrons from one substrate to another. Alcohol dehydrogenase.
transferases
Transfer of functional groups from one compound to another. Hexokinase.
enzyme nomenclature
1st number = 1 of 6 main divisions/classes of enzymes. 2 = subclass. 3 = sub-subclass. 4 = serial number.
6 main divisions of enzymes
oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases
holoenzyme
catalytically active enzyme-cofactor complex
apoenzyme
inactive enzyme (absence of cofactor)
[S] > Km
ES favoured over E + S
[S] < Km
E + S favoured over ES
hapten
a small molecule which, when combined with a larger carrier such as a protein, can elicit the production of antibodies which bind specifically to it
sulfanilamide
antibiotic useful in treatment of kidney infection. Structural analogue of PABA (which is structural part of folic acid)
sulfanilamide competitively inhibits…
bacterial dihydrofolate synthetase (which
uncompetitive inhibition
inhibitor binds to enzyme-substrate complex (NOT to free enzyme). Doesn’t bind to active site but can cause distortion of active site.
competitive inhibitors act by…
reducing the concentration of free enzyme available for substrate binding
alkaline phosphatase
catalyses release of inorganic phosphate from phosphate esters. Uncompetitively inhibited by phosphate.
alkaline phosphatase found in
liver, bile ducts, intestine, bones, kidneys, placent, leukocytes
larger L value means that T-R equilibrium lies…
further toward T state. (MWC model)
n (in MWC model) = amount of substrate that can bind.
the higher the n value, the more the equilibrium can be shifted toward R state
