Physiology Flashcards
how much is the rate increased when carbonic anhydrase is added ?
0.1 –> 1,000,000 per second
what are enzymes made up of?
proteins; amino acids and other chemical groups (eg. metal ion)
&/or RNA(eg. Ribosomes)
what is K cat
the number of molecules of substrate that one enzyme molecule can convert in 1 second
define prosthetic group or co-enzyme
metal ions or organic molecules
define apoenzyme
an enzyme with ought an essential cofactor or coenzyme
define holoenzyme
enzyme + coenzyme (complete machinery)
where does trypsin hydrolyse phenylalanine, tyrosine, or tryptophan?
the peptide bonds at the C terminus
what determines the activity and specificity of an enzyme?
the structure and chemistry of the active site
what are the qualities of an active site?
- 3 dimensional structure
- site can come together from different parts of the polypeptide chain
- site forms a cleft or crevice
- many week non covalent interactions between substrate and active site groups
what is induced fit
enzymes adjust binding
what is it called when the enzyme is bound?
transition state
what does the transition state mean for the reaction?
different pathway with lowering the activation barrier
what is Michaelis complex?
enzyme-substrate complex
what is the Michaelis -menten equation & what can it derive?
- affinity, selectivity, efficiency, inhibitor characteristics, pharmacology
what are drugs?
inhibiters – enzymes + receptors are the target
what is the regulation of relevant metabolites?
product feedback inhibition, such as ATP. mechanism involves allosteric binding
example of feedback inhibition :
threonine to isoleucine pathway - 5 enzymes, first is inhibited by isoleucine
what is the regulation by proteins?
some are 1:1
some proteins mediate control of enzymes by interpreting other signals.
– does this by calcium and calmodium
what is regulation with reversible covalent modification?
phosphorylation
kinases and phosphates are regulated by what?
by revesable covalent modification - other enzymes or products
controlled proteolysis:
made in the inactive form
does allosteric regulation follow michealis mention kinetics?
no - it has a sigmoidal curve
what does an inhibiter do?
mimic the substrate
example of an inhibitor?
PALA - competitive
- this allows us to catches the protein in flagrant
effect of PALA vs CTP:
PALA - promotes relaxed state – makes it favoured by substrate
CTP - less active t state
what is the graph of ATCase?
sigmoidal - understood by imagining an allosteric enzyme as a mixture of two michealis mention enzymes.
