Question #b7458

1 Answer
Apr 24, 2016

Answer:

#k_"cat" = "250 s"^"-1"#

Explanation:

The Michaelis-Menten model of enzyme catalysis is

#E + S stackrelcolor(blue)(k_f)(⇌) ES stackrelcolor(blue)(k_"cat"color(white)(m))(→) E + P#
#color(white)(mmmm)stackrelcolor(blue)(k_r)(color(white)(l))#

If the enzyme concentration is much less than the substrate concentration, the rate of product formation is

#(d[P])/dt = V_"max" ([S])/(K_"M" + [S]) = k_"cat" [E]_0 ([S])/(K_"M" + [S])#

The maximum rate #V_"max"# is attained when all of the enzyme molecules are bound to the substrate.

It follows from the Michaelis-Menten equation that

#color(blue)(|bar(ul(color(white)(a/a) V_"max" = k_"cat"[E]_0color(white)(a/a)|)))" "#

#[E]_0# is the initial enzyme concentration and #k_"cat"# is the turnover number — the maximum number of substrate molecules converted to product per enzyme molecule per second.

#k_"cat" = V_"max"/[E]_0 = (30 × 10^"-6" color(red)(cancel(color(black)("mol·L"^"-1")))"min"^"-1")/(2 × 10^"-9" color(red)(cancel(color(black)("mol·L"^"-1")))) = "15 000 min"^"-1" = "250 s"^"-1"#