Statistical evaluation of ways to analyze nonideal systems by sedimentation equilibrim

Three equations describing sedimentation equilibrium are examined and tested for their ability to analyze data. The testing procedure using simulated data is similar to that described previously (Holladay, L. A., and Sophianopoulos, A. J. (1972) J. Biol. Chem.247, 427–439) and used with another equation. The equations examined here are found to be of much less statistical reliability and of a more restricted range of application than the previously examined equation. The equation described previously, (Holladay, L. A., and Sophianopoulos, A. J. (1972) J. Biol. Chem.247, 427–439) is also used here to examine the conditions necessary to detect isodesmic systems of more than four components. The self-association of lysozyme reported previously (Sophianopoulos, A. J., and Van Holde, K. E. (1964) J. Biol. Chem.239, 2516–2524) is reexamined at pH 8.2, 0.15 ionic strength, and 13°C. The tentative conclusion is that the system is mainly a monomer-dimer, with a small, uncertain amount of tetramer possibly present. Under the above conditions the second virial coefficient, B, is estimated to lie in the range 0–4.4 × 10^?6 mole·dl·g^?2, the dimerization constant. K₂₁, lies in the range 2.3–2.7 × 10^?3m, and the tetramerdimer constant, K₄₂, is in the range 1.5–15 × 10^?3m.     

Thermodynamics of carp metmyoglobin unfolding

The conformational free energy of carp lateral muscle metmyoglobin at 25 degrees C pH 8 is 9.0 +/- 0.5 kcal/mol as estimated from isothermal unfolding by both urea and guanidinium chloride. A novel procedure for the simultaneous analysis of acid and guanidinium chloride unfolding data is described. Acid denaturation data suggest that binding of five protons to histidyl residues occurs on unfolding. Correlation of sequences and conformational stabilities of several myoglobins according to the tertiary structure of sperm whale myoglobin suggests an evolutionary turnover of side chain-side chain interactions.     

Nonspecific stimulation of the maternal immune system. I. Effects On teratogen-induced fetal malformations

BACKGROUND: Maternal immune stimulation has reported, but unconfirmed, efficacy for reducing chemical-induced morphologic defects in mice. METHODS: Teratogenic chemicals (2,3,7, 8-tetrachlorodibenzo-p-dioxin [TCDD], ethyl carbamate [urethane], methylnitrosourea [MNU], or valproic acid [VA]) were given to pregnant mice to induce cleft palate (TCDD, urethane), digital defects (urethane, MNU), or exencephaly (VA). Before teratogen administration, the immune system of female mice was stimulated by intraperitoneal (IP) administration of pyran copolymer or attenuated bacillus Calmette Guérin (BCG), or by footpad injection with Freund's complete adjuvant (FCA). RESULTS: Fetal defects caused by all four chemicals studied were reduced by maternal immunostimulation, sometimes dramatically. In addition to reducing VA-induced exencephaly, immunostimulation with FCA resulted in fetal mice displaying anury (absence of tails). Activated maternal immune cells could not be detected in fetal circulation using flow cytometry and a fluorescent cell-tracking probe. CONCLUSIONS: For the chemicals tested, maternal immune stimulation has efficacy in reducing fetal defects. Immune protection against teratogenesis may be an indirect effect of maternal immune cell activation.     

Analytical techniques for cell fractions. XIX. The cyclum: an automatic system for cyclic chromatography.

An automatic system, termed a Cyclum, is described which allows column chromatographic separations to be repeated precisely a large number of times. Provision is made for the adjustment during operation of parameters such as equilibration, wash, elution, and sample flow times and duration of fraction collection. The system is applicable to both analytical and preparative use in various types of column chromatography (e.g., affinity, gel filtration, ion-exchange), but has been especially developed for separations based on immunosorption.     

Phenol and phenolics from lignocellulosic biomass by catalytic microwave pyrolysis

Catalytic microwave pyrolysis of biomass using activated carbon was investigated to determine the effects of pyrolytic conditions on the yields of phenol and phenolics. The high concentrations of phenol (38.9%) and phenolics (66.9%) were obtained at the temperature of 589 K, catalyst-to-biomass ratio of 3:1 and retention time of 8 min. The increase of phenol and its derivatives compared to pyrolysis without catalysts has a close relationship with the decomposition of lignin under the performance of activated carbon. The concentration of esters was also increased using activated carbon as a catalyst. The high content of phenols obtained in this study can be used either directly as fuel after upgrading or as feedstock of bio-based phenols for chemical industry.     

Conformational free energies of myoglobins of small mammals

Myoglobins from three small placental mammals and one small marsupial were isolated from cardiac or skeletal muscle. The conformational free energies of these four myoglobins were estimated from guanidinium chloride unfolding data at pH 8 and 25 degrees. The myoglobins from rat and rabbit are more stable than that of the most stable myoglobin previously studied, that of the sperm whale. In addition, these two myoglobins unfold with greater cooperativity than previously characterized myoglobins. The data obtained herein demonstrate unequivocally for the first time that the stability of homeotherm myoglobins correlates with neither the size of the organism nor its metabolic rate.