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M A LAUFFER

Publications and source records attributed to M A LAUFFER.

At least 19 recordsLinked to original sources
PubMed1963

Polymerization-depoly-merization of tobacco mosaic virus protein. I. Kinetics.

It was shown that a reversible endothermic association of TMV protein subunits (A protein) can take place at pH values below the isoelectric point as well as at pH 6.5. The polymerization occurring below the isoelectric point was found to be more complex than that at pH 6.5 probably because products other than the usual TMV-like rods were formed in addition to those rods and also because side-to-side aggregation of the rods took place readily. Kinetic studies indicated that polymerization can be treated as a second-order linear condensation. The rate of polymerization was found to be a critical function of pH, having a maximum value near pH 4.3. This behavior is at variance with the hypothesis that hydrogen-bonded carboxyl pairs play a dominant rate-determining role in the association of subunits. The dependence of the rate on pH was interpreted to indicate that electrostatic forces between subunits are a significant controlling factor in the polymerization of TMV protein.

Isoelectric Point↗
PubMed1961

Theory of diffusion in gels.

It has been shown that when concentration of solute is expressed as amount per unit volume of gel-solvent-solute system, Fick's laws for diffusion in a gel take the same form as for diffusion in solvent alone, except that the usual coefficient must be replaced by a new coefficient, D', equal to D(1 - alphaphi)/(1 - phi), where phi is the effective volume fraction of the gel substance and alpha is a coefficient of obstruction equal to 5/3 if the gel substance can be considered to be made up of randomly oriented rods. An equation was derived for the total amount of solute entering the gel, which is analogous to but not identical with the equation for the total amount of solute crossing the initial boundary in free diffusion. The effect of slice thickness was investigated by a mathematical procedure involving the solutions of approximate differential equations. It was shown that even for slices so thick that 95 per cent of the solute in the gel is contained in the first two, a correction factor equal to the square of the slice thickness divided by 48D't permits one to obtain accurate measurement of D' from the mean concentration and the position of the midplane of the slice.

Diffusion↗