Alexander J. Charlson

Cytoplasmic and Cell Surface Deoxyribonucleic Acids with Consideration of their Origin

Publisher Summary Advanced biochemical and biophysical techniques are used to differentiate cytoplasmic and cell surface deoxyribonucleic acids (DNA) from nuclear DNA and to counter the trivial argument that such DNA is a contaminant produced during the preparation. The evidence from biochemistry and morphology indicates that three separate compartments exist for accommodation of cellular DNA—nuclear, cytoplasmic including the plasma membrane, and extracellular or excreted DNA. If these three compartments are a part of a covalently linked polymer system, as seems not unlikely, then an interchange possibly of great velocity among the compartments is equally as likely. It is possible in such a close-knit system that a rearrangement of the carbohydrate chains of surface glycoprotein would be inevitably accompanied by a rearrangement of the sequence of a nucleotide polymer formed on the surface at the time. Biochemical methods are concerned with cell fractionation studies using centrifugation in various media. They reveal that a varying but small fraction of the DNA is found in postmitochondrial fractions, which in different studies may or may not vary from the nuclear DNA in several respects, including molecular weight, specific activity, sensitivity to antimetabolites, melting profile, and buoyant density.

Antineoplastic constituents of some Southern African plants.

Extracts of several Southern African plants which have been used in folk remedies have been prepared, and the extracts were tested in a variety of experimental tumour test-systems. Raphionacme hirsuta and Cheilanthes contracta have been used in African anticancer medicines. Extracts of these plants showed antitumor activity in some rodent test-systems, but the results were not confirmed. In the folk-lore, Haemanthus natalensis has been used in emetics and Urginea capitata preparations have been used to vaccinate African chiefs. Extracts of these plants showed significant cytotoxicity in the KB cell culture test-system. Infusions of Brunsvigia radulosa have been used as folk remedies for abdominal troubles. An extract of this Amaryllis plant increased the life span of P-388 leukaemic mice. Amaryllis bellandonna has also been investigated. Extracts of Amaryllis belladonna had to be fractionated in order to produce significant antitumour activity in the P-388 lymphocytic leukaemia test-system.

The methanesulfonylation of 2-benzimidazolemethanol and α(2-benzimidazolyl)benzyl alcohol

Abstract Treatment of 2-benzimidazolemethanol ( 4 ) with methanesulfonyl chloride and pyridine in chloroform afforded 2-(chloromethyl)-1-(methylsulfonyl)benzimidazole ( 6 ), which was also prepared by methanesulfonylation of 2-(chloromethyl)benzimidazole. Methanesulfonylation of α-(2-benzimidazolyl)benzyl alcohol ( 8 ) in chloroform yielded 2-(α-chlorobenzyl)-1-(methylsulfonyl)benzimidazole. 1-(Methylsulfonyl)-2-benzimidazolemethanol was obtained on methanesulfonylation of 4 pyridine at 0°, and α-[1-(methylsulfonyl)-2-benzimidazolyl]benzyl alcohol ( 12 ) was prepared from 8 by using the same reaction conditions. The reaction of 1-acetyl-2-(chloromethyl)-benzimidazole with silver methanesulfonate in benzene gave 1-acetyl- O -(methylsulfonyl)-2-benzimidazolemethanol. Compound 6 has some antitumor activity in the KB cell-culture system, and some antibacterial activity in the Staphylococcus aureus test-system; it is also active in preventing anaphylactic shock in a mouse test-system.

The effect of metal ions on the hydrolysis of L-asparagine by L-asparaginase

Abstract A variety of main group and transition metal ions have been studied as moderators of the enzymatic hydrolysis of L-asparagine by L-asparaginase. The greater deactivations were produced by mercury(II), copper(II) or tetrachloropalladate(II) ions when each moderator was incubated with the enzyme before the hydrolysis reaction was initiated. Different results were observed for copper(II) and mercury(II) when the moderator was incubated with the substrate before adding the enzyme; in this latter situation the copper(II) ion appears to act as a co-factor for the reaction. It has been shown that in the presence of each of the metal ions chosen the energy of activation of the moderated enzymatic hydrolysis reaction remains unchanged from that of the control reaction.

Ultrastructural studies of the effects produced by some amino acid metal systems on Escherichia coli B

Abstract Escherichia coli cells were grown in the presence of L-serine and gallium(III) nitrate a different molar ratios. Under these conditions ultrastructural changes were observed in the cells when examined under the electron microscope. Although some changes were seen inside the cell the major modifications were observed at the cell surface. These changes appeared to involve both the cell and the peptidoglycan layer. Autoradiography at the electron microscope level undertaken with similar mixtures and containing L-(3 - 3H) serine showed silver grains at or near the cell surface. In some cases, surface modifications were so pronounced that they resulted in the E. coli appearing as sheets of cells. No cell surface changes were detected when mixtures of L-serine and potassium tetrachloropalladate(II) were used as modifying agents. With the palladium(II) mixtures all changes observed were intracellular. These modifications included the appearance of membrane-bound vehicles, clumping of the cytoplasm and changes in the nucleoplasm. Autoradiography carried out in the presence of L-(3 - 3H) serine showed a significant proportion of silver grains over the nuclear region. A pure palladium(II) complex of L-serine was examined as a modifying agent in the concentration range 1–9 μ/cm 3 resulting in very pronounced modification of the cells when exposed to higher concentrations.

Crystal structure of poly[[μ3-(S)-2-amino-3-hydroxy­propano­ato]-cis-di-μ-chlorido-caesium­palladium(II)]

This compound was previously shown to have anticancer activity in rodent test systems and recently found to have antifungal activity. The Pd centre is in a square-planar coordination environment with two chlorine atoms in cis positions and the remaining two coordination sites being coordinated by N and O atoms from deprotonated l-serine. Each of the Cs cations shows ninefold coordination with six chlorine and three O atoms resulting in a coordination environment that is similar to the well known Cs2SO4 structure.