| | 1 | Author
| Harald Labischinski, Dieter Naumann, Gerhard Barnickel, Wolfgang Dreißig, Wojciech Gruszecki, Andreas Hofer, Hans Bradaczek | Requires cookie* | | | Title
| Comparison between the Molecular and Crystal Structures of a Benzylpenicillin Ester and its Corresponding Sulfoxide with Drastically Reduced Biological Activity  | | | | Abstract
| A comparative X-ray structure determination was performed to elucidate possible conforma-tional differences between penicillins and penicillin sulfoxides. Penicillin-G-acetoxy-methylester and its Iß-oxide were used as model substances, because the only chemical difference between both compounds resides in the thiazolidine ring sulfur oxidation. On the basis of the X-ray data as well as of infrared measurements it is discussed that the drastically reduced biological activity of the penicillin-G-sulfoxide might be related to conformational differences in thiazolidine ring puckering or, even more simply, to the geometric position of the sulfoxide oxygen atom, both of which may hamper the proper reaction of the sulfoxide with its target enzyme(s). | | | |
Reference
| Z. Naturforsch. 42b, 367—375 (1987); received June 30/0ctober 14 1986 | | | |
Published
| 1987 | | | |
Keywords
| X-Ray, Penicillin G, Penicillin G Sulfoxide, Thiazolidine Ring Conformation, Structure Activity Relationships | | | |
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| | | | | TEI-XML for
| default:Reihe_B/42/ZNB-1987-42b-0367.pdf | | | | Identifier
| ZNB-1987-42b-0367 | | | | Volume
| 42 | |
| 2 | Author
| Frank Beise, Harald Labischinski, Hans Bradaczek | Requires cookie* | | | Title
| On the Relationships between Molecular Conformation, Affinity towards Penicillin-Binding Proteins, and Biological Activity of Penicillin G-Sulfoxide | | | | Abstract
| 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 of binding activity (about two orders of magnitude) of the sulfoxide derivative towards its target enzymes. Furthermore, the sulfoxide did not exhibit the selectivity of subinhibitory doses for PBP 3, as could be observed for penicillin G. The biological consequences of this behaviour were monitored via growth curves, uptake of cell wall label, and analysis of the cell wall. Binding studies revealed that comparable growth inhibi-tion and impairment of cell wall label uptake were achieved by at least a 100-fold higher penicillin G-sulfoxide concentration, compared to its parent compound. In cell wall analysis, the application of high doses of the antibiotics, i.e. nearly saturated PBP, verified the above mentioned observation. Surprisingly, small but significant differences in cell wall composition occurred using subinhibitory doses, probably due to the altered affinity towards PBP 3, supporting the hypothesis of an important role of this PBP in peptidoglycan transpeptida-tion. | | | |
Reference
| Z. Naturforsch. 43c, 656—664 (1988); received March 25/June 28 1988 | | | |
Published
| 1988 | | | |
Keywords
| Penicillin G, Penicillin G-Sulfoxide, Penicillin-Binding Proteins, Biological Activity, Structure Activity Relationships | | | |
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| | | | | TEI-XML for
| default:Reihe_C/43/ZNC-1988-43c-0656.pdf | | | | Identifier
| ZNC-1988-43c-0656 | | | | Volume
| 43 | |
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