Bio molecules Proteins & Enzymes Flashcards
Which type of peptides hydrolyses middle bonds.
Endopeptidase
Which type of peptidase hydrolysed end bonds
Exopeptidase
Describe the induced fit-model of enzyme action and how an enzyme acts as a catalyst.
Active site changed shape so it is complementary to the substrate nearby.
Forms enzyme-substrate complexes.
Reduces the Ea.
Suggest + explain procedure scientists can use to stop reaction.
Boil to denature the enzyme.
As we inc inorganic phosphate concentration what happens to ATP conc?
More enzyme-substrate complexes can be formed so the conc of ATP inc.
Plateaus when all active sites occupied.
How does a competitive inhibitor dec rate of an enzyme-controlled reaction?
-they bind to enzymes active site
-change AS shape
-AS no longer complementary to substrate
-Enzyme-substrate complexes no longer form so ROR slows.
How could eating bread that contains retrograded starch (competitive inhibitor of amylase) lead to weight loss?
Less hydrolysis of starch to maltose so less absorption of glucose.
Describe how the structure of a protein depends on the AA it contains?
-primary structure is determined by position of AA
- this can change the SS of H bonding between AA
- can then affect TS in between R groups
- can change the shape of the AS
Describe how AA a join to form a pp so NH2 is always at one end and COOH is always at the other end.
-AA joined together by condensation reactions to form peptide bond.
- one NH2 group joins to COOH to form a peptide bond.
-so one free NH2 at one end and free COOH at the other
How does the AS of an enzyme cause a high ROR?
-induced fit causes AS of enzyme to change shape becoming complementary to substrate
- so enzyme-substrate complexes cause bonds to break
-lowers Ea
-inc ROR
Chemical test to confirm presence of protein
Biuret test - biuret reagent - positive purple
2 similarities of all dipeptides
-NH2 group at end
-COOH group at end
Difference of dipeptides
Different R groups on AA
AA current chromatography explained AA movements
- AA that move closer to negative electrode are positively charged
- diff AA spots move diff distances bc AA have diff charge
-overlapping spots = AA have same charge
How does a non-competitive inhibitor dec rate of enzyme-controlled reaction?
-The non-competitive inhibitor bonds to enzyme but not on AS.
-However this still changes shape of AS.
- enzyme-substrate complexes can no longer form
-ROR dec
How did scientists conclude that the inhibitor is non-competitive?
With inhibitor inc, substrate conc inc does not inc ROR
Describe how a peptide bond is formed between 2 AA.
Condensation reaction between 2 AA to form peptide bond between NH2 group and COOH group.
-water released
Describe how the SS of a pp is prod by bonds between AA
-base seq PS determines the SS of H abounds between NH and C=O
Two proteins have same no. + type AA but diff tertiary structure. Why?
- the AA seq is diff
- forms ionic + H bonds in diff places
- diff TS
How does formation of enzyme substrate complexes inc ROR
-reduces Ea bc w/o enzyme very few substrates have sufficient energy for reaction.
Effects to consider of AA changes
- whether negative to positive charge changed in AA or other way around
- whether change affects AS if involved in ionic bond (AS will change).
