1. Several factors could change Vmax. a. Would either [S] or [E] change the valu
ID: 221965 • Letter: 1
Question
1. Several factors could change Vmax.
a. Would either [S] or [E] change the value of Vmax? Explain your answer.
b. Would pH or temperature alter the value of Vmax? Explain your answer.
2. It is commonly know that freshly cut fruits turn a brownish color when exposed to the air for a number of minutes (see below). This is due to the action of the enzyme polyphenoloxidase. It is also well known that the formation of the brown color can be prevented or slowed by chilling the fruit, boiling it, or rubbing it with lemon juice (which contains ascorbic acid). Explain why each of these three methods work to slow down the browning process.
Explanation / Answer
Vmax is the maximum velosity of an enzymatic reaction, when all the enzyme active sites are occupied with substrate. Active site is the portion of an enzyme, where catalysis process takes place.
a. Upon increasing the substrate concentration, enzyme velocity also increased upto certain limit and follows first order kinetics. Once all the active sites filled with substrate, there in no furthur increase of enzymatic velocity and it follows zero order kinetics. So Velocity increase with respect to substrate concentration till all the active sites of enzyme filled with substrate.
Once the enzymatic reaction reached zero order kinetics, by increasing enzyme concentration, we can turnup the zero order kinetics into first order kinetics. That means, when high concentration of substrate is present, then the zero order become first order and increase the enzyme velosity with respect to increase the enzyme concentration
b. 3D structure of an enzyme is essential for enzymatic catalysis and Vmax. pH and Temperature upto certain extent promotes enzymatic reactions and supports Vmax. Called optimum pH & Temperatures. When the pH & Temperature are deviate from optimum values, then the velocity of the enzyme decreased due to distrubance of the enzyme 3D structure
2. Poly phenol oxidases produces free radicles which are reacts with ferrous particles of the fruit and produce brown color. This is mainly due to action of Poly phenol oxidases. These Poly phenol oxidases are inactivated by Chilling or Boiling. So no free radicles produced and no brown color is produced.
Lemon juice contain Ascorbic acid which is free radicle scavinger. So it neutralize the all free radicles. So no browning takes place
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.