Destroying the Trojan horse. Penicillin is hydrolyzed and thereby rendered inactive by penicillinase (also known as β-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. [Penicillin] μM Amount hydrolyzed (nmol) 1 0.11 3 0.25 5 0.34 10 0.45 30 0.58 50 0.61
a. Plot V0 versus [S] and 1/V0 versus 1/[S] for these data. Does penicillinase appear to obey Michaelis-Menten kinetics? If so, What is the value of KM ?
b. What is the value of Vmax ?
c. What is the turnover number of penicillinase under these experimental conditions? Assume one active site per enzyme molecule