Polyion complex micelles formed from glucose oxidase and comb‐type polyelectrolyte with poly(ethylene glycol) grafts

The comb‐type polyelectrolyte, poly(ethylene glycol)‐graft‐poly(allyl amine) (PEG‐g‐PAA), was synthesized to prepare polyion complex (PIC) micelles with Aspergillus Niger Glucose oxidase (GOD). Even after mixing GOD and PEG‐g‐PAAs with various PEG contents, the resulting mixtures remained transparent but the mixture of GOD and PAA homopolymer immediately precipitated. In the mixtures prepared with a stoichiometric mixing ratio, the formation of PIC micelles with a core‐shell structure was suggested from dynamic and static light scattering measurements. Glucose, the substrate for GOD, could easily diffuse into the PIC micelles, and the GOD molecules were active even in the core of the PIC micelles. GOD didn't lose its enzymatic activity through entrapment into the PIC micelles. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3842–3852, 2008     

Quantum chemical CD calculations of dioncophylline A in the solid state

Although dioncophylline A (1) is the certainly best-investigated naphthylisoquinoline alkaloid, it still represents a challenging case for theoretical stereochemical investigations. Its biaryl axis, although being configurationally stable, still has a certain degree of rotational flexibility, rapidly twisting within certain margins, and thus, exerting a dramatic influence on the CD behavior of 1. Therefore, solid-state CD spectroscopy might provide a unique chance to study this flexible compound in a conformationally ‘frozen’ form, as fixed in the crystal. Based on the X-ray derived coordinates of the single conformer found in the crystalline state, CD calculations were performed by three different approaches, viz. by CNDO/S-CI, TD-B3LYP, and DFT/MRCI, each permitting the unambiguous attribution of the absolute axial configuration of dioncophylline A (1) as P, which is in full agreement with the previous assignments. Furthermore, to examine a possible influence of the neighboring molecules in the crystal on the CD behavior of 1, a set of dyads, each consisting of a given ‘central’ molecule and a second one from the nearest neighborhood, were considered at a semiempirical level, as well as a ‘one-piece’ cluster of 16 molecules from the crystal. The results were compared with those obtained by solution and solid-state CD spectroscopy, which confirmed the configurational assignment.