CHEM 3050 Lecture Notes - Lecture 36: Enzyme Kinetics, Turnover Number, Competitive Inhibition
3 May 2018
School
Department
Course
Professor
CHEM 3050
Lecture 36
o Random Sequential – binding of substrates
and then the release of the products is not
ordered
o Ping-Pong – substrate binds first, first product
is formed and released (Enzyme often modified;
E F)
▪ Second substrate binds to form the second
product and the enzyme is regenerated.
- Multi-step reactions: Kcat is hard to find (still the
same—enzyme’s turnover number)
- Allosteric enzymes: Presence of substrate in one
active site affects catalytic activity at another active
site.
o Usually has multi-subunit complexes
Irreversible Enzyme Inhibition
- Some inhibitors act irreversibly
o Such as groups that are covalently attached to
the enzyme (ex: DIPF on Chymotrypsin)
- Some are suicide substrates
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Document Summary
Lecture 36: random sequential binding of substrates and then the release of the products is not ordered, ping-pong substrate binds first, first product is formed and released (enzyme often modified; E f: second substrate binds to form the second product and the enzyme is regenerated. Multi-step reactions: kcat is hard to find (still the same enzyme"s turnover number) Allosteric enzymes: presence of substrate in one active site affects catalytic activity at another active site: usually has multi-subunit complexes. Some inhibitors act irreversibly: such as groups that are covalently attached to the enzyme (ex: dipf on chymotrypsin) Some are suicide substrates: bind like a normal substrate but unable to complete the reaction and get stuck in the active site. Inhibitor binding affects kcat, km or both: competitive inhibition, compound resembles substrate, it occupies the active site and prevents the substrate from binding, binding of s and i are mutually exclusive.
