Hist + asp deprotonate and activate OH in serine - nucleophile . attacks C=O in scilce bond. O becomes -ve charged and can now move deeper into the AS - this is called the tetrahedral IM
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2. Stabalisation/ tetreahedal IM
AS rearranges itself to stabalise -ve charge. This part is called the oxyanion hole. Peptide bond breaks by proton transfer by his to the new amino group. 1st product released
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3. acyl enzyme + product release
enzyme sub complex forms acyl enzyme intermediate . activated water acts as nucleophile and attacks - 2nd product release amd free enzyme regenerated
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Cystein MOA
very similar to serine - but has S as nucleophile
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aspartate MOA (general acid base )
2 asp residues - 1 acts as acid the other base - see enzyme lecture
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MMP MOA
requires metal ion to stabalise structure - this is often zinc
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1 step catalysis
aspartate , MMPs and glutamine activate water to act as a nucleophile - this is 1 step catalysis . Serine on the other hand is not
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Substrate locations right of scicle bond
P1' P2' P3'
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to the left of scile bond
P1 P2 P3
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most important location for specifity
P1
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types of serine protease
trypsin , elastase
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where does trypsin cleave
after positibe charge - due to -ve charge in bottom of the AS binding pockets
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