KINETIC ANALYSIS OF PENICILLOIC ACID AND PENICILLOAMIDES IN COMBINATION - APPLICATION TO PRODUCTS OF REACTION OF PENICILLIN WITH TROMETHAMINE (TRIS) AND POLY-L-LYSINE

Studies of chemical reactions related to penicillin allergy often require an assay for both penicilloic acid and penicilloamides in reaction mixtures. Previous assays were based on conversion of these substances, with HgCl2, to penamaldates which have an absorption maximum at 282 mμ. Differentiation of the two compounds was accomplished by taking advantage of the lower stability of the penamaldate of penicilloic acid using only the absorbance initially and after 10 min. The present work describes an improved method based on the fact that decay of penamaldate can be resolved kinetically into its two components. Extrapolation to zero time yields very accurate estimates of molar extinction coefficients. The method was applied to products of reaction of tromethamine (Tris) with penicillin which is catalyzed by poly‐L‐lysine (PLL). In absence of tromethamine both penicilloic acid and penicilloyl‐PLL are formed while at high tromethamine concentration the product is almost entirely N‐(penicilloy1)‐tromethamine. Calculated rates show that PLL catalyzes hydrolysis of penicillin to penicilloic acid as well as aminolysis by tromethamine. These results confirm the previously proposed reaction mechanism. Copyright © 1969 Wiley‐Liss, Inc., A Wiley Company