The inhibitory effect of the polypeptide antibiotics netropsin and distamycin A on DNA dependent nucleic acid synthesis has been shown to be related to the base composition of the template DNA. A number of natural DNA's of quite different dA-dT content as well as poly (dI-dC)-poly (dI-dC), poly (dA-dT)-poly (dA-dT), poly (dA) - poly (dT) and poly (dG) - poly (dC) has been studied as templates in DNA and in part in RNA polymerase reaction. The highest binding efficiency of netropsin existing for (dA-dT) - containing DNA polymers and the less pronounced interaction with the (dI-dC)-containing polymer shown by the melting and CD spectrral behaviour of the complexes are entirely reflected in the template inactivation. The same is evident for distamycin A. However, in contrast to netropsin the antibiotic distamycin A exhibits some binding tendency to poly (dG) - poly (dC). Binding effects of a netropsin derivative to DNA and (dA-dT) -containing polymers suggest the importance of hydrogen bonds of the peptide groups in the complex formation.
Summary
Conditions of separation of bovine spermatozoa according to their differences in electrophoretic mobility were studied using free‐flow electrophoresis. Distribution of spermatozoa in the electric field depends on composition of buffer system, field intensities and temperature. Conditions are described for reproducible separation of anodically migrating spermatozoa into two distinct peaks both for cold‐immobilized (10–13 °C) and for motile cells (25 °C). Electrophoresis with the buffer used at 25 °C and field intensities of 70–100 V/cm provided high percentages of motile spermatozoa (50–90%) in all fractions. However, the sperm distribution across the fractions was the result of superimposed passive electrophoretic motion towards the anode and the active galvanotactic migration towards the cathode. Separation of X‐ and Y‐ spermatozoa was verified by quantification of Y‐spermatozoa by means of both in situ hybridization, using Y‐specific DNA fragments, and the Y‐specific fluorescence staining (f‐body test). Y‐spermatozoa could be enriched in anodic fractions (112 and 144% relative to control). X‐spermatozoa were enriched in cathodic fractions (80 and 68% Y‐spermatozoa, as compared to control).
Resistomycin preferentially inhibits RNA synthesis in comparison to DNA and protein synthesis in intact bacterial cells. Studies with cell-free systems have shown that the antibiotic interferes with DNA and RNA synthesis, while protein synthesis is inhibited to a much lesser extent. Detailed studies in cell-free systems indicate an interaction of resistomycin with DNA- and RNA polymerase. In the case of RNA polymerase this was proved by CD measurements, whereas no interaction of the antibiotic with DNA, RNA, and homopolynucleotides could be found. One can conclude that the binding of the antibiotic to RNA polymerase is the basis for its interference with RNA synthesis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.