penicillin g acylase from e. coli ta1 was immobilized by cross-linked enzyme aggregates (clea), a new method for immobilization. this biocatalyst and commercial immobilized penicillin g acylase (pga-450) were used to study the effect of ph, temperature and substrate concentration on the synthesis of ampicillin from phenyl glycine methyl ester (pgme) and 6-aminopenicillanic acid (6-apa). compare...

The concentrations of penicillin in the cerebrospinal fluid (CSF) were compared simultaneously with those in the serum in 17 patients with syphilis. The antibiotic concentrations were measured by the agar well diffusion method. There were no detectable concentrations of penicillin in the CSF after administration of benzathine penicillin 2.4 megaunits, benzathine penicillin 7.2 megaunits, procai...

The binding capacity of penicillin G-sulfoxide towards the penicillin-binding proteins (PBP) of Staphylococcus aureus H was studied. The sulfoxide and its parent compound, penicillin G, differ only in two aspects, the sulfur-bound oxygen and an altered conformation of the five-membered thiazolidine-ring system. These minor alterations of the penicillin structure resulted in a drastical decrease...

Penicillin acylase (EC 3.5.1.11) catalyses the condensation of phenylacetic acid (PAA) and 6-aminopenicillanic acid (6-APA) to form benzylpenicillin (BP). Both PAA and 6-APA were found to form host-guest complexes with beta-methylcyclodextrin (beta m-CD) and gamma-cyclodextrin (gamma-CD) respectively. The rate of the reaction catalyzed by the enzyme remained unaffected if one of the substrates ...

In this paper some numerical restrictions for surfaces with an involution are obtained. These formulas are used to study surfaces of general type S with pg = q = 1 having an involution i such that S/i is a non-ruled surface and such that the bicanonical map of S is not composed with i. A complete list of possibilities is given and several new examples are constructed, as bidouble covers of surf...

The Chicxulub crater is the only wellpreserved peak-ring crater on Earth and linked, famously, to the K-T or K-Pg mass extinction event. For the first time, geologists have drilled into the peak ring of that crater in the International Ocean Discovery Program and International Continental Scientific Drilling Program (IODP-ICDP) Expedition 364. The Chicxulub impact event, the environmental calam...

M. L. Laanen [email protected] Institute for Environmental Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands Current address: Water Insight BV, Marijkeweg 22, 6709 PG Wageningen, The Netherlands S. W. M. Peters Institute for Environmental Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands A. G. Dekker CS...

There are two known families of maximum scattered Fq-linear sets in PG(1, q): the linear sets of pseudoregulus type and for t ≥ 4 the scattered linear sets found by Lunardon and Polverino. For t = 4 we show that these are the only maximum scattered Fq-linear sets and we describe the orbits of these linear sets under the groups PGL(2, q) and PΓL(2, q).