Partial molar quantity of an intensive mother function

Direct combination of the Lewis acids, Me3M (where M = B, Al, Ga, or In), and the diamines, Me2N(CH2)nNMe2 (where n = 1, 2, or 3) has given two series of complexes. A range of 1:1 complexes can be isolated with Me2NCH2NMe2 as ligand. With the other diamines, use of a 1:1 molar ratio of reactants yields crystalline 2:1 complexes with two moles of Me3M per mole of ligand. Excluding the reaction between Me3B and Me2NCH2NMe2, 2:1 complexes can be isolated by reacting the various Lewis acids with the appropriate molar quantity of the diamines. The complexes have been characterized by i.r. and proton n.m.r. spectroscopy and molecular weight measurements.A number of complexes of Me3Ga with methyl substituted ethylenediamines have been prepared and the effects of substitution on the nitrogen ligand atoms studied. Pyrolysis of these complexes has demonstrated the ready elimination of methane and has resulted in the formation of condensed Ga—N species.

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Inhibition of microtubule polymerization by micromolar concentrations of mercury(II)

Canadian Journal of Biochemistry and Cell Biology ◽

10.1139/o84-103 ◽

1984 ◽

Vol 62 (9) ◽

pp. 814-818 ◽

Cited By ~ 11

Author(s):

Robert A. B. Keates ◽

Brian Yott

Keyword(s):

Chelating Agents ◽

Tetraacetic Acid ◽

Microtubule Polymerization ◽

Microtubule Protein ◽

Molar Quantity ◽

Total Hg ◽

In Vitro Inhibition

Polymerization of microtubule protein in vitro has been tested in the presence of Hg2+. Inhibition occurs in the presence of Hg2+ concentrations lower than the molarity of the tubulin, even in the presence of 0.5 mM ethylenebis(oxyethylene-nitrilo)tetraacetic acid. The estimated concentration of free Hg2+ under these conditions is less than 10−20 M. The extent of inhibition is approximately stoichiometric in that the molar quantity of tubulin that fails to polymerize is comparable to or slightly greater than the total Hg2+ present as chelate. The affinity of the susceptible site for Hg2+ in microtubule protein must be exceptionally high and may not be protected by natural chelating agents in the cell. Preformed microtubules are rapidly depolymerized on addition of Hg2+ chelate. In vitro, inhibition is both prevented and rapidly reversed by 2-mercaptoethanol.

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The Varieties of Flow Meters

Measuring Metabolic Rates ◽

10.1093/oso/9780198830399.003.0017 ◽

2018 ◽

pp. 207-216

Author(s):

John R. B. Lighton

Keyword(s):

Ambient Temperature ◽

Mass Flow ◽

Barometric Pressure ◽

Flow Meter ◽

Flow Meters ◽

Standard Temperature ◽

Molar Quantity ◽

Temperature And Pressure

This chapter discusses the most frequently used flow meters in respirometry. These include the volumetric rotameter, which is affected by ambient temperature and barometric pressure; and the mass flow meter, which directly measures the molar quantity of air passing through it, and thus automatically corrects the volume to standard temperature and pressure. The operation and calibration of each type of meter are discussed.

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t-PA PROTEIN DETERMINATION: IMPROVED ACCURACY THROUGH COMPOSITION CONSIOUS AMINO ACID ANALYSIS (CCAAA)

10.1055/s-0038-1644408 ◽

1987 ◽

Author(s):

A Brändström ◽

M Rånby

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Standard Deviation ◽

Amino Acid Composition ◽

Acid Composition ◽

Amino Acid Analysis ◽

Reference Method ◽

Protein Determination ◽

Molar Quantity ◽

The Mean

Protein determination by composition consious amino acid analysis (CCAAA) is generally applicable to polypeptides with known amino acid composition.Traditionally, in protein determination by AAA the mass of protein substance in a preparation is quantitated by simple summation of the mass of all amino acid residues found, although some amino acids e.g. Trp, Ser, Thr, Cys are unsatisfactorily determined. In this study we have explored the, possibility of improving protein determination by AAA in cases where the amino acid composition of the preparation is precisely known from sequence data. In CCAAA protein determination the molar amounts of amino acids that are known to be quantitatively recovered are divided by the number of residues known to be present in the polypeptide. The mean of these values is identified as the molar quantity of polypeptide in the sample. In addition, the standard deviation of the mean serves as identification and homogeneity control. In this study the accuracy of the method was checked gravimetrically.CCAAA was applied on t-PA prepared from cultured Bowes melanoma cells by immunopurification on PAMl-Sepharose 6BFF and subsequent gelfiltration in 1 mol/L NH4HCO3 on Sephacryl SA-200. About 2 pg of lyophilized protein was hydrolysed in 6 mol/L HC1 under vacuum for 24 hours at 110°C and amino acid analysed. Amino acids selected for calculation of the molar quantity were (number of residues within parentheses) Asp+Asn(50), Glu+Gln(52), Pro(29), Ala(32.5), Val(25), Leu(39), His(16), Lys(21) and Arg(35.5). To obtain the gravimetric quantity the molar quantity was multiplied with the theoretical molecular weight as calculated from the sequence and with the carbohydrate content taken into account.For t-PA the standard deviation of the mean molar quantity typically was less than 5%. The result from CCAAA was about 10% higher than that obtained from conventional AAA. The result from CCAAA was within 10% of that found gravimetrically. The absorbtivity of t-PA was estimated to 1.75 (g/L)-1cm-1.In summary, composition consious amino acid analysis (CCAAA) is recommended as reference method for protein determination of well defined protein preparations where the amino acid composition is known.

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