A review of: “Micelles: Theoretical and Applied Aspects.” Yoshikiyo Moroi. Plenum,New York, 1992. pp. ix + 252. 559.50. (ISBN 0-306-43996-4).

Abstract

We examine here the adsorption of weak, acidic, rigid macro‐ions onto oppositely charged surfaces using a mean field model. The analysis takes into account the effect of the nominal suspension pH on the charge distribution inside the macro‐ion layer, as well as the counter‐ion distribution in the adsorbed layer and in the solution surrounding the substrate. We find that, as expected, the adsorbed layer thickness decreases with the pH (namely, with the degree of charge dissociation) and with the solution ionic strength. The macro‐ion adsorption can, in some cases, over‐compensate for the substrate charge, thereby allowing layer‐by‐layer deposition. We find that charge inversion is obtained, for a given substrate, if the macro‐ion pK is lower than a critical value. For a given macro‐ion, charge inversion takes place if the substrate charge density exceeds a critical value that scales as the square root of the macro‐ion charge density. In both cases charge inversion is obtained only in the regime where the suspension pH is comparable to the pK.     

Hydrolysis Reaction of N-Phosphoryl-α-, β- and γ-amino Acids Studied by HPLC

The hydrolysis reactions of N-（O,O＇diisopropyl）phosphoryl-L-α-alanine （DIPP-L-α-Ala）, N-（O,O＇diisopropyl）- phosphoryl-D-α-alanine （DIPP-D-α-Ala）, N-（O,O＇-diisopropyl）phosphoryl-β-alanine （DIPP-β-Ala） and N-（O,O＇-diisopropyl）phosphoryl-γ-amino butyric acid （DIPP-γ-Aba）, were studied by HPLC and their hydrolysis reaction kinetic equations were obtained. Under acid conditions, the reaction rate of DIPP-L-α-Ala was close to that of DIPP-D-α-Ala and the same rule was true between DIPP-β-Ala and DIPP-γ-Aba. Meantime, the reaction rate of DIPP-L/D-α-Ala was as 10 times as that of DIPP-β-Ala or DIPP-γ-Aba. Under basic conditions, the hydrolysis reactions of DIPP-β-Ala and DIPP-γ-Aba almost did not take place and the reaction rate of DIPP-L/D-α-Ala was about 1/10 of that under acid conditions. Moreover, theoretical calculation further illuminated the differences of the hydrolysis rate from the view of energy. The results would provide some helpful clues to why nature chose a-amino acids but not other kinds of analogs as protein backbones.