Left-handed Unit Research Articles

Synthesis of the left-hand unit of the antitumour agent CC-1065

The cyclopropapyrroloindole (3), the left-hand unit of the antitumour agent CC-1065 (1), has been synthesised from 3-hydroxyacetophenone by a route which involves construction of both pyrrole rings by thermolysis of vinyl azides.

The autonomous parvovirus MVM encodes two nonstructural proteins in addition to its capsid polypeptides

In vitro translation of mRNA from cells infected with the autonomous parvovirus MVM yields four major virally coded proteins. Two of these proteins are indistinguishable both antigenically and by peptide map analysis from the viral capsid polypeptides VP-1 and VP-2. The other two proteins, designated NS-1 and NS-2, are not related to the capsid polypeptides but are recognized by sera from animals infected with different autonomous parvovirus serotypes. The NS-1 protein made in vitro comigrates with VP-1 (MW approximately 83,000), while the NS-2 polypeptide has an apparent molecular weight of 24,000. The transcript for the NS-1 polypeptide was mapped to a block of open reading frame located in the major intron of the left-hand transcription unit in the MVM genome.

Structure of the cell wall of the Gram-negative bacterium Proteus vulgaris: II. Distribution of electron density across the wall

Isolated cell wall preparations of Proteus vulgaris consist of arrays of two components: the complete cell wall (comprising the rigid mucopeptide and protein layer or R layer, a lipopolysaccharide layer and a lipoprotein layer) of thickness 144 Å; and a spheroplast wall of thickness 92 Å corresponding to the cell wall after the loss of the labile R layer. The first-order low-angle X-ray reflexion corresponding to the thickness of each wall component is diffuse, but the higher orders are sharp. It is shown that this occurs if the distribution of electron density through the thickness of each component is non-centrosymmetrical and if the occurrence is random of right- and left-handed parallel sheet structures within the specimens. The interpretation of the X-ray data is made in terms of a centrosymmetrical average structure for each component which is the result of superimposing right- and left-handed units. For both the 92 Å spheroplast wall and the complete wall, with phases determined by reference to the electron micrographs, the average centrosymmetrical structures were found by trial-and-error methods. A method is then described of separating the superimposed right- and left-handed units and thus producing non-centrosymmetrical structures for the spheroplast and whole cell walls. These structures are closely related to the structures observed by electron microscopy, but they also make use of the information contained in the X-ray diffraction patterns. Although the electron density distributions so deduced are to some extent arbitrary, they are entirely consistent with the X-ray data, so far as phase angles may be assigned to the reflexions, and they are of a nature such that slight distortions would produce images similar to those seen in the electron microscope after embedding and sectioning.