B: Enzyme Action - Environmental Effects

Question 1

environmental effects on enzyme action

Answer 1

-Turnover Number: Total number of substrate molecules that can be processed by enzymes
-Turnover Rate: Number of substrate molecules processed by an enzyme over 1 minute time and 10^3 to 10^16 times faster than un-catalyzed reactions

Question 2

optimize turnover number: what is optima?

Answer 2

temperature, pH, concentration

Question 3

optimum temperature:
what is it?
it acts by?

Answer 3

• Temperature at which the maximum turnover rate
  is achieved
  – It acts by either altering molecular motion or altering structure

Question 4

optimum temperature: lower vs higher than optimum

Answer 4

-Temperature is lower than optimum: reactions may slow or stop like Preserving foods in freezers

–Temperature is higher than optimum: proteins are denatured = irreversibly inactivated by heat (even if the temperature is lowered) like High fevers

Question 5

what is optimum pH?

Answer 5

-pH at which the maximum turnover rate is achieved
–pH influences the shape of the enzyme due to charge

Question 6

what pH does optimum pH function best at?
too acid?
too alkaline?
exceptions?

Answer 6

-Most function best at neutral pH 7.0
-Too acid means too many H+ may collect in active site, so that substrate cannot bind effectively. it may denature protein enzymes
-Similar results in denaturation for too alkaline
-Exceptions: Stomach enzymes function best at acid pH 1-2 and Liver enzymes function best at basic pH 9-10

Question 7

what is cellular control processes?

Answer 7

-the right thing in the right amount at the right time
-it controls enzyme turnover rate
-coordination = time + sequence
-regulation= amount

Question 8

active site occupation: what is enzyme occupation?

Answer 8

-More than one enzyme can use the same substrate to create different products
-Example: Two enzymes that perform the same function, one
works best under certain temperatures vs. the other