Showing papers in "Journal of Molecular Biology in 1968"

TL;DR: An analysis of the solvent content of 116 different crystal forms of globular proteins found that in many cases this range will be sufficiently restrictive to enable the probable number of molecules in the crystallographic asymmetric unit to be determined directly from the molecular weight of the protein and the space group and unit cell dimensions of the crystal.

TL;DR: It is considered that originally only a few amino acids were coded, but that most of the possible codons were fairly soon brought into use and the code became frozen in its present form.

TL;DR: It is proposed that the mechanism of the reaction involves the joining of short, homologous sites on the two strands followed by a fast, reversible zippering reaction with forward rate constant kt, which explains the temperature and the GC dependence.

TL;DR: It is suggested that the replication of the bacterial genome during the division cycle of Escherichia coli Br growing with doubling times between approximately 20 and 60 minutes can be described by two constants: C and D, the time for a replication point to traverse the genome.

TL;DR: The amount of tritiated thymidine incorporated into the DNA of irradiated cells indicates that pyrimidine dimers in the DNA inhibit DNA synthesis but are not permanent blocks, and that the daughter-strand DNA synthesized after ultraviolet-irradiation contains gaps, or alkalilabile bonds.

TL;DR: It is argued that the evolution of the genetic apparatus must have required the abiotic formation of macromolecules capable of residue-by-residue replication, and suggests that polynucleotides were present even in the most primitive ancestors of contemporary organisms.

TL;DR: It is found that the long fibers of which chromosomal DNA is composed are made up of many tandemly joined sections in each of which DNA is replicated at a fork-like growing point.

TL;DR: The physical property which distinguishes actinomycin from the simpler analogs (which lack biological activity) is a very slow dissociation reaction, several orders of magnitude slower than for the non-active analogs.

TL;DR: The results thus confirm the sharp distinction between the RNA of prokaryotic and eukaryotic organisms and show that there has been a strong conservation of molecular size during evolution, and suggest that the increased size of the animal ribosome was essential for animal evolution.

TL;DR: Three heterogeneous RNA species in HeLa cells have been characterized with respect to kinetics of labeling, turnover and location, showing that the nucleoplasmic, cytoplasmic and polyribosome-associated messenger fractions are relatively unaffected by doses of actinomycin which completely inhibit ribosomal RNA synthesis.

TL;DR: It is concluded that histones can mask DNA in chromatin and prevent it from acting as a template, but this effect is nonspecific.

TL;DR: The nuceloplasm and nucleolus of HeLa cells contain six distinct low molecular weight species of RNA that are long-lived and do not appear to be precursor to any cytoplasmic product.

TL;DR: In this paper, it was shown that the cell age at which rounds of DNA replication begin is variable and depends upon the growth rate, and that the time for a complete round of replication is constant and independent of the growing rate.

TL;DR: The recombinational behavior of int mutants in wild-type and recombination-deficient bacteria suggests that the int + gene determines a site-specific function involved in normal prophage integration and detachment.

TL;DR: Phosphofructokinase has been partially purified from Escherichia coli, and its kinetic properties investigated, finding co-operative interactions with respect to one of its substrates, fructose-6-phosphate, but not towards the second, namely ATP.

TL;DR: The location of the disulphide bridges in the chemical sequence of trypsin suggests thattrypsin and chymotrypsin have nearly identical tertiary structures, and that their disulPHide bridges serve to stabilize rather than to determine the structure.

TL;DR: It is established that 30 s particles are monomers of a more complex polysome-like structure, which is formed by a long D-RNA strand and a number of globular protein particles bound to it and tightly packed along the D- RNA strand.

TL;DR: The present experiments indicate that this extra protein, termed accessory protein, is released from the subunits when they are incorporated into polyribosomes as a polydisperse array of ribonucleoprotein complexes with a relatively uniform RNA to protein ratio.

TL;DR: The nucleotide sequence of the low molecular weight ribosomal RNA (5 s RNA) of Escherichia coli has been studied using 32P-labelled RNA and paper fractionation techniques and a new two-dimensional procedure suitable for fractionating oligonucleotides up to 25 residues long is described.

TL;DR: In this article, a structure is proposed to explain the X-ray diffraction pattern of a naturally occurring cross-β fibrous protein, which contains ribbon-like micelles about 25 A with their longest dimension parallel to the fibre axis.

TL;DR: A method for measuring sequence homology between high specific activity RNA's and DNA of Xenopus laevis is described and the relative abundance of nucleotide sequences homologous to rRNA and 5 s RNA in X. laevIS liver, erythrocyte, and embryonic DNA has been found to be similar.

TL;DR: Colicinogenic factor E1 (Col E1) DNA isolated from Escherichia coli by phenol extraction followed by dye-buoyant centrifugation was found to consist almost exclusively of the monomer 23 s supercoiled circular DNA form.

TL;DR: A simple device is described which permits the optical superposition of skeleton atomic models and three-dimensional electron-density maps and the model of a globular protein can be built directly “into the map”.

TL;DR: A genetic demonstration is presented that thymine starvation leads to the initiation of a new round of DNA replication, even if the chromosome is already being replicated at the time thymine is withheld.

TL;DR: It is argued that the function of the peptide deformylases is to remove the formyl group from nascent protein, which is quite labile under a variety of experimental conditions and is inhibited strongly by thiols.

TL;DR: It is calculated that the closed circular molecule contains −15 ± 1 superhelical turns in buoyant cesium chloride at neutral pH, and it is estimated that the melting temperature of polyoma I in standard saline citrate should be 107 °C.

TL;DR: The results support the conclusion that the pattern and evolution of late RNA abundances during T4 development has its origin in changing rates of transcription and not in changing stabilities.

TL;DR: The three-stranded poly d(T-C)·d(G-A)·(U-CH + ) was characterized by cesium sulfate buoyant density studies, by continuous variations study, by ultraviolet spectral properties and by optical density-temperature profiles.

TL;DR: Results of experiments with cells not treated with guanidine are consistent with a precursor-product relationship and the stability of top component under numerous conditions suggests that it is not in equilibrium with subunits and that it are thus a true precursor of virions.