Factor-free and one-factor-promoted poly(U,C)-dependent synthesis of polypeptides in cell-free systems from Escherichia coli

α-Tropomyosin from rat cardiac muscle was shown by two-dimensional gel electrophoresis to become phosphorylated when tissue slices were incubated in Eagle's medium supplemented with ³²P_i. In the adult rat and mouse heart the level of phosphorylation was ～30%, but the level was much higher in the foetal heart (60–70%). A similar developmental trend was observed in skeletal muscle from the rat and mouse, where phosphorylated forms of both α- and β-tropomyosins were observed. When rat cardiac cells were grown in tissue culture in the presence of ³²P_i, radioactivity was incorporated into the region of the gel containing tropomyosin.     

The Benzodiazepine/GABA Receptor Complex: Molecular Size in Brain Synaptic Membranes and in Solution

Abstract: The molecular size of the benzodiazepine (BZ) receptor in the synaptic membrane of brain cortex (bovine or rat) was determined by an improved version of the radiation inactivation method to be 220,000. An identical size was found simultaneously for the associated γ-aminobutyric acid (GABA) receptor and for the component binding β-carboline esters. It is proposed that all three activities reside in a single protein or protein complex in the membrane. The size in solution, after extraction into Triton X-100 medium from exhaustively washed membranes, was estimated by sedimentation constant (9.4S) and by gel filtration (∼230,000 apparent MW), again with the BZ and GABA binding activities behaving identically. This size applies to the component that undergoes photoaffinity labelling by [³H]flunitrazepam in the membrane, and contains a 51,000 M_r polypeptide as the BZ-binding subunit. It is concluded that a protein complex or oligomer of 200,000–220,000 MW carries a class of BZ-binding sites and an associated class of GABA_A sites.     

The old REH theory remains unsatisfactory and the new REH theory is problematical - a reply to holmquist and jukes

Summary In response to criticism of REH theory (Fitch 1980), Holmquist and Jukes (1981) have mostly avoided the criticism or misunderstood it. Since they themselves state in their response that Amino acid sequence data alone cannot be used to estimate total nucleotide substitutions, they agree with the criticism. Most of their paper treats the newer theory (here designated as the REHN theory) which attempts to use the nucleotide sequences encoding proteins to better estimate total nucleotide substitutions (Holmquist and Pearl 1980). Since I made no criticism of REHN theory, their comments are frequently beside the point of my original criticism of REH theory. Nevertheless, it is shown here that REHN theory is also unsatisfactory in that: One, the varions are now more clearly defined but in such a way as to preclude the same codon from suffering a nucleotide substitution in more than one evolutionary interval. Two, the set of codons that accepts silent substitutions is identical to the set that accepts amino acid changing nucleotide substitutions. Three, the uncertainty in the REH estimate is considerable in that alternative excellent fits to the same observatuonal data may give alternative REH values that differ significantly even before stochastic variation and selective bias are considered. Four, the fit of their model to data is an irrelevancy where there are zero degrees of freedom.     

Seven sesquiterpene lactones from Inula britannica var. chinensis

Four known sesquiterpene lactones, tomentosin, ivalin, 4-epi-isoinuviscolide and gaillardin, together with three new lactones, inuchinenolides A, B and C, were identified in the whole plant of Inula britannica var. chinensis.     

Lipoxygenbase-derived products of arachidonic acid mediate stimulation of hexose uptake in human polymorphonuclear leukocytes

The titration of metal-freed bovine α-lactalbumin with Mg²⁺ ions causes a two-stepped decrease in the tryptophan fluorescence quantum yield and a pronounced spectral shift towards shorter wavelengths, which seems to be a result of the binding of two magnesium ions to the protein molecule. The magnesium binding constants evaluated from the fluorimetric Mg²⁺-titration are 2·10³ and 2·10² M^?1. Mg²⁺ ions in millimolar concentrations almost do not influence the binding of Ca²⁺ ions to the protein.     

NMR of fd coat protein

The conformations of the major coat protein of a filamentous bacteriophage can be described by nuclear magnetic resonance spectroscopy of the protein and the virus. The NMR experiments involve detection of the ¹³C and ¹H nuclei of the coat protein. Both the ¹³C and ¹H nuclear magnetic resonance (NMR) spectra show that regions of the polypeptide chain have substantially more motion than a typical globular protein. The fd coat protein was purified by gel chromatography of the SDS solubilized virus. Natural abundance ¹³C NMR spectra at 38 MHz resolve all of the nonprotonated aromatic carbons from the three phenylalanines, two tyrosines, and one tryptophan of the coat protein. The α carbons of the coat protein show at least two different classes of relaxation behavior, indicative of substantial variation in the motion of the backbone carbons in contrast to the rigidity of the α carbons of globular proteins. The ¹H spectrum at 360 MHz shows all of the aromatic carbons and many of the amide protons. Titration of a ¹H spectra gives the pKas for the tyrosines.     

Antimetabolic activities of 2-fluoro-L-histidine.

2-Fluoro-L-Histidine inhibits protein synthesis in various cell cultures, as measured by ³H-leucine incorporation. This histidine analog also inhibits the cytopathogenicity of a number of RNA and DNA viruses in primary and continuous cell cultures; it blocks the transformation of normal mouse (MO) cells by murine sarcoma virus, and partially suppresses the release of murine leukemia virus by a continuously infected mouse cell line (JLSV5). In human skin fibroblasts, it reduces the interferon-inducing capacity of poly(I)·poly(C). Inhibition of cell protein synthesis may be the common cause of the various effects. 4-Fluoro-L-histidine is essentially inert in all of the test systems examined.