Penicillin is hydrolyzed and thereby rendered inactive by penicillinase (also known as ?-lactamase), an enzyme present in some penicillin-resistant bacteria. The mass of this enzyme in Staphylococcus aureus is 29.6 kDa. The amount of penicillin hydrolyzed in 1 minute in a 10 mL solution containing 10 ^-9 g of purified penicillinase was measured as a function of the concentration of penicillin. Assume that the concentration of penicillin does not change appreciably during the assay.

(a) Plot Vo versus [S] and 1/V _o versus 1/[S] for these data. Does penicillinase appear to obey Michaelis-Menten kinetics? If so, what is the value of K _M ?

(b) What is the value of V _max ?

(c) What is the turnover number of penicillinase under these experimental conditions? Assume one active site per enzyme molecule.

[Penicillin] Amount hydrolyzed (m) (nmol) 1 13 3 5 10 30 50 0.11 0.25 0.34 0.45 0.58 0.61