The formation of 2-hydroxy-4-hydroxymethyl-3-(indol-3-yl)-cyclopent-2-enone derivatives from ascorbigens

A facile preparation is described of 3-(indol-3-yl)-2-hydroxy-4-hydroxymethylcyclopent-2-enone and its N-derivatives in 15-40% yields by the degradation of ascorbigen or its N-derivatives in a warm solution of L-ascorbic acid through a sequential domino reaction. The same cyclopentenone derivatives were obtained in 30-40% yields by the condensation of (N-alkylindol-3-yl)glycolic acids with ascorbic acid. 2,6-Dihydroxy-1-(indol-3-yl)hexa-1,4-diene-3-one and 2-hydroxy-4-hydroxymethyl-5-(indol-3-yl)cyclopent-2-enone were identified as intermediates in this reaction.     

Polymorphism of membrane proteinases from mitochondria

Using native polyacrylamide gel electrophoresis in the absence of sodium dodecyl sulfate, the detergent extracts of sonic submitochondrial particles (SMP) were separated into three protein fractions capable of accomplishing the proteolysis of cytochrome c and three other fractions catalyzing the hydrolysis of N-a-benzoyl-L-arginine-p-nitroanilide (BAPA) and N-a-benzoyl-L-arginine-B-naphthylamide (BANA). The fractions isolated from the gel were subjected to a thorough anaylsis. Cytochrome c hydrolases were shown to have identical molecular weights (17000) but different isoelectric points (4.0, 4.2 and 4.4). The total cytochrome c hydrolase activity of these enzymes was inhibited by phenylmethylsulfonylfluoride but was insensitive to ethylenediaminetetraacetate and o-phenanthroline. Three BANA (BAPA) hydrolases have identical Mr values (approximately 17500) but different pI values (4.2, 4.3 and 4.7). Apart from the indicated hydrolases, the detergent extracts of SMP were shown to contain minor components with identical activities distinguished by the tightness of binding to the inner mitochondrial membrane, Mr and sensitivity to proteinase inhibitors. The observed phenomenon is considered to be due to the polymorphism of proteinases coupled with the inner mitochondrial membrane.     

Modification of olivomycin A at the side chain of the aglycon yields the derivative with perspective antitumor characteristics

A novel way of chemical modification of the antibiotic olivomycin A (1) at the side chain of the aglycon moiety was developed. Interaction of olivomycin A with the sodium periodate produced the key acid derivative olivomycin SA (2) in 86% yield. This acid was used in the reactions with different amines in the presence of benzotriazol-1-yl-oxy-trispyrrolidino-phosphonium hexafluorophosphate (PyBOP) or diphenylphosphoryl azide (DPPA) to give corresponding amides. Whereas olivomycin SA was two orders of magnitude less cytotoxic than the parent antibiotic, the amides of 2 demonstrated a higher cytotoxicity. In particular, N,N-dimethylaminoethylamide of olivomycin SA showed a pronounced antitumor effect against transplanted experimental lymphoma and melanoma and a remarkably high binding constant to double stranded DNA. The therapeutic effects of this derivative were achievable at tolerable concentrations, suggesting that modifications of the aglycon’s side chain, namely, its shortening to methoxyacetic residue and blocking of free carboxyl group, are straightforward for the design of therapeutically applicable derivatives of olivomycin A.     

Correlation between the rate of proteolysis of mitochondrial translation products and fluidity of the mitochondrial inner membrane in Saccharomyces cerevisiae yeast. Alteration of the rate of proteolysis under glucose repression.

Our previous results [Kalnov, Novikova, Zubatov & Luzikov (1979) FEBS Lett. 101, 355-358; Biochem. J. 182, 195-202] suggested that in yeast the mitochondrial translation products localized in the mitochondrial inner membrane are rapidly broken down by a proteolytic system inherent in the membrane. In the present work, it is demonstrated that, on glucose repression in undividing cells of Saccharomyces cerevisiae, there is no proteolysis of the mitochondrial translation products. This effect is not likely to be associated with lower activity of the proteolytic system of the mitochondrial inner membrane. Nor is the cessation of proteolysis due to qualitative changes in the composition of mitochondrial translation products. What repression does cause is a considerable alteration in the physical state (i.e. structure of the lipid bilayer) of the mitochondrial inner membrane; this was established by experiments involving lipid-soluble spin probes. The conclusion is reached that the rate of proteolysis of mitochondrial translation products in the mitochondrial inner membrane depends on the physical state of the membrane, which in its turn is controlled by the relative content of unsaturated fatty acid chains in the mitochondrial phospholipids.     

Coexpression of all constituents of the cholesterol hydroxylase/lyase system in Escherichia coli cells

Using the pTrc99A/P450scc vector, a plasmid was constructed in which cDNAs for cytochrome P450scc, adrenodoxin reductase, and adrenodoxin are situated in a single expression cassette. This plasmid was shown to direct the synthesis of all the above proteins in Escherichia coli. Their localization in the E. coli cells and stoichiometry were determined. Cell homogenates exhibited cholesterol hydroxylase/lyase activity, due to catalytically active forms of all three proteins. Thus, the full set of constituents of the mammalian cholesterol hydroxylase/lyase system was shown to be synthesized in bacterial cells for the first time.