ISSN:0006-3525    

DOI:10.1002/bip.1969.360070102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractThe osmotic pressure equation for nonideal, associating systems of the typenA +mB ⇄ AnBm, has been derived, by using the assumptionyAnBm/yAnyBm= 1. This treatment can also be applied to related associations such asnA + mB ⇄ AB + AB2+ A2B + …. From osmotic pressure experiments on the pure reactants it is possible to obtain the molecular weights (MAandMB) of the reactants and also the virial coefficients (BAAand BBB) of the reactants. The osmotic pressure of a nonreacting mixture of A and B can be calculated from these measurements. It can be used along with osmotic pressure measurements on equilibrium mixtures of A and B to obtain expressions containing the equilibrium constant (or constants) and the cross‐virial coefficients (BABand BBA). Several procedures are described for the evaluation of the equilibrium constant (or constants) and the BABor BBAterms. It appears that this procedure is a general one which is applicable to associations of the typenA +mB ⇄ AB + A2B + AB2+ …. By correcting for nonideal behavior, one should then be able to apply it to any method available for analyzing ideal associations of the types considered here. In addition it is possible, subject to certain restrictions, to analyze associations of the type 3A +

ISSN:0006-3525    

DOI:10.1002/bip.1969.360070103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractThe physical properties of a pathological γM‐globulin with cold agglutinin activity and cryoglobulin solubility could be modified by changes in temperature and pH and upon dilution. The type of changes noted appear to simulate those expected in a readily dissociable antigen‐antibody complex. Naturally occurring and chemically produced subunits of the γM‐globulin and Fc‐fragments of myeloma proteins diminished the cryoproperty of the γM‐globulin and effected changes in its physical properties but did not alter its cold agglutinin activity. Cryoglobulin properties could be conferred upon some purified γM‐globulins by reacting them with Fc‐fragments. Mercaptan dissociation of the Cryomacroglobulin produces subunits with loss of the noted activities. Reaggregation of these subunits restores some of the native properties, but variable results which are dependent on the type of mercaptan employed are obtained. Attempts to explain the cold agglutinin activity of γM‐globulin hybrids containing variable amounts of mercaptan‐produced active and inert subunits suggest that activity requires two of the five subunits to be derived from the γM‐cold agglutinin and to

ISSN:0006-3525    

DOI:10.1002/bip.1969.360070104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractA method has been developed for characterizing at, submicrogram levels the heterogeneity of histones from purified nuclei. The histones are eluted with a smooth concentration gradient from nuclei trapped in polyacrylamide–gel threads and are collected in a micro fraction collector suitable for volumes in the 10–100 μl range. The gradient and fraction collection systems are governed by cam driven syringes. Samples obtained are subjected to electrophoresis in a starch‐gel system and the gels are stained with a highly sensitive stain specific for guanidinium groups. Seven major and a similar number of minor components are demonstrated in the histones. The method of differential elution of trapped macromolecules is suitable for use with systems other than nuclei and hi

ISSN:0006-3525    

DOI:10.1002/bip.1969.360070105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractUnder the assumptions that the rectangular approximation to the sector‐shaped cell is valid and that both the sedimentation coefficientsand the diffusion coefficientDare independent of concentration, asymptotic solutions to the boundary spreading equation for velocity ultracentrifugation of polydisperse solutes have been derived for three cases: case A,D= constant for alls; case B,sD= constant; case C,\documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt {sD} = {\rm constant} $\end{document}. Case A is the situation treated by all of the previous authors but supposed to be unrealistic for ordinary macromolecular solutes. Cases B and C may be associated with synthetic polymers under theta conditions and globular proteins in aqueous media, respectively. The solutions obtained have been used to explore the theoretical background of the empirical Gralén method for evaluating the distribution ofsfrom sedimentation boundary curves, with special interest in the behavior of a plot forSversus 1/t. HereSis the value ofsfor a fixed value of the apparent integral distribution ofsandtis the time of centrifugation. It was found that when the distribution ofsis Gaussian‐like and fairly narrow, this plot becomes linear over a more extended range oftin the order case B>case C>ca

ISSN:0006-3525    

DOI:10.1002/bip.1969.360070106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractWhen rat liver ribosomes were dissociated by removing their magnesium, the two subunits hads 020,w of 52.6 and 28.1 S, and appeared to be quite asymmetrical. In 4Murea they became even more elongated. On restoration of magnesium, both subunits assumed more compact forms, 57.6 and 31.7 S, but only 28% of them formed larger aggregates. After brief treatment with formaldehyde, the magnesium‐free subunits still elongated in urea, but to a lesser degree than the controls. When magnesium was restored they changed to 53.4 and 31.7 S forms, but did not, aggregate. The ribosomal subunits were also separated by reducing the bound magnesium to a low level, then adding 2.2Murea. After the urea had been dialyzed out, most of the large subunits were still in a compact form and when the magnesium concentration was increased, most of the subunits did not reassociate to whole ribosomes. Formaldehyde‐treated subunits, however, did not reassociate. Even in their most compact forms, 60.0 and 35.5 S, both subunits had high frictional ratios. The 60.0 and 31.7 S forms were assumed to be the shapes that are seen in electron micrographs of negatively stained ribosomes. Both subunits seemed to be highly hydrated. Since the large subunit appeared to contain twice as much water as the small one, it might be a structure with either a deep channel or a hollow c

ISSN:0006-3525    

DOI:10.1002/bip.1969.360070107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractA consideration of the meaning of the second moment method for the determination of sedimentation coefficients reveals potential convective instability in the sedimentation of all reversibly aggregating systems for which dissociation is favored by pressure.

ISSN:0006-3525    

DOI:10.1002/bip.1969.360070108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractA new method is proposed for finding molecular weights from the boundary condition of the ultracentrifuge. The method is more rapid than the conventional Archibald method by at least one order of magnitude and should be especially useful for giant molecules with small diffusion coefficients. It employs a preset concentration gradient. A theoretical study of the method has been made by obtaining solutions to the Lamm equation analogous to the “mirror image” solution (for early times) and the Fourier expansion solution (for late times) of Mason and Weaver. Numerical examples of theoretical results are given, and the errors are discussed. Centrifugation in a preset linear gradient can also be used to reduce the time needed to reach equilibr

ISSN:0006-3525    

DOI:10.1002/bip.1969.360070109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractThe myosin molecule was extracted from the smooth muscle parts of horse esophagus and purified by ammonium sulfate fractionation. The schlieren pattern of the sedimentation velocity run showed a very sharp single peak of.5.9. S (s20,w). Molecular weight of the protein was measured by means of the Archibald and sedimentation equilibrium methods, both in 0.5MKCI buffered by 1/150Mphosphate at pH 7.5 and at 5°C. The values obtained were 6.25 × 105and 5.81 × 105respectively, for the two methods. The second virial coefficients were 1.1 × 104and 1.2 × 10−4ml/g. Denatured smooth muscle myosin was prepared in a solution of 5Mguanidine HC1 containing 0.4MKC1 and 0.2Mβ‐mercaptoet hanol buffered at pH8.0. The weight‐average molecular weight of the denatured smooth muscle myosin was 2.24 × 105and the second virial coefficient was 7.6 × 10−4ml/g. The values described above are in good agreement with those reported for rabbit skeletal myosin with ammonium sulfate fractionation. The molecular dimension of the molecule is estimated as the value for an axial ratio of 100, assuming a rigid rod molecular model for this molecule, both the thermodynamical and hydrodynamical treatment being in a good agreement with

ISSN:0006-3525    

DOI:10.1002/bip.1969.360070110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractTwo new methods for the measurement of diffusion coefficients were introduced. In the first method the spreading is measured from a. thin layer in a cylindrical tube containing a suitable gel. To avoid convection in the gel the tube is rotated horizontally round its long axis. In the second method the diffusion spreading is measured from an initial thin layer under a column of solvent in a Tiselius electrophoresis cell or a micro cuvet of a spectrophotometer. The great advantage is the economy on the material investigated.

ISSN:0006-3525    

DOI:10.1002/bip.1969.360070111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY