Search

The β-lactamase-catalyzed hydrolysis of penicillins can be followed by a novel NMR method. During the reaction, methyl proton signals of the penicillin decrease in intensity, while new methyl signals of the product, penicilloic acid, appear and increase in intensity. The half-life is easily measured as the time for the signals to be of equal intensity. With 6-aminopenicillanic acid, which is the precursor to a large number of semisynthetic penicillins, the reaction rate follows the Michaelis-Menten expression. In D 2 O at pD 7.0, 29°C, the presence of 5′-AMP raises the values of both apparent V max and apparent K m . An explanation for the rise in apparent V max is that a ternary enzyme-substrate-AMP (ESA) complex is formed which reacts faster than ES. An explanation for the rise in apparent K m is that the dissociation of ESA is greater than ES. At 0.068 M , penicillin-G hydrolyzes 10 times faster than 6-aminopenicillanic acid. The rate of hydrolysis of penicillin-G is unaffected by the presence of 5′-AMP.

Under the assumption of a perfect gas with a constant specific heat ratio, the first approximation of the integral-relations method, which considers the entire shock layer as a single strip, is derived for axisymmetric bodies of arbitrary smooth contour. The resulting differential equations were then applied to a supersonic and hypersonic flow past a paraboloid of revolution. The shock shapes, shock wave detachment distances, locations of sonic lines; and velocity and pressure distributions for the body were calculated for γ = 1.4 and y = 5/3, and at Mach numbers of 3, 4, 6, 10 and 1000. These calculations were carried out on an IBM 1620 electronic computer. The results were compared with those obtained by Van Dyke's inverse method. The agreement between the two methods was found to be good, in view of the fact that only the first approximation of the integral relations method was used. Master of Science