Induced circular dichroism of cyclodextrin inclusion complexes: examining the cavity with a bilateral probe

The induced circular dichroism (ICD) of 1@7-Cy gives rise to an unusual spectrum which can be explained by a positive and a negative contribution of two identical chromophores. This finding is in agreement with rules predicting the ICD of chiral supramolecular systems.

Chemospecific monofunctionalization of alpha-cyclodextrin in the solid state

[reaction: see text] The properties of the self-assembling aziadamantane inclusion complex with two alpha-cyclodextrin molecules have been exploited to perform a chemospecific monofunctionalization of alpha-cyclodextrin. The insertion of the photochemically generated carbenes takes place chemospecifically into the cyclodextrin's C-3-OH and C-2-OH bonds in 39 and 18% yield, respectively. This model reaction surpasses conventional methods in terms of yield as well as selectivity.

Effect of distal cavity mutations on the formation of compound I in catalase-peroxidases.

Catalase-peroxidases have a predominant catalase activity but differ from monofunctional catalases in exhibiting a substantial peroxidase activity and in having different residues in the heme cavity. We present a kinetic study of the formation of the key intermediate compound I by probing the role of the conserved distal amino acid triad Arg-Trp-His of a recombinant catalase-peroxidase in its reaction with hydrogen peroxide, peroxoacetic acid, and m-chloroperbenzoic acid. Both the wild-type enzyme and six mutants (R119A, R119N, W122F, W122A, H123Q, H123E) have been investigated by steady-state and stopped-flow spectroscopy. The turnover number of catalase activity of R119A is 14.6%, R119N 0.5%, H123E 0.03%, and H123Q 0.02% of wild-type activity. Interestingly, W122F and W122A completely lost their catalase activity but retained their peroxidase activity. Bimolecular rate constants of compound I formation of the wild-type enzyme and the mutants have been determined. The Trp-122 mutants for the first time made it possible to follow the transition of the ferric enzyme to compound I by hydrogen peroxide spectroscopically underlining the important role of Trp-122 in catalase activity. The results demonstrate that the role of the distal His-Arg pair in catalase-peroxidases is important in the heterolytic cleavage of hydrogen peroxide (i.e. compound I formation), whereas the distal tryptophan is essential for compound I reduction by hydrogen peroxide.

On the hypothetical protein F154 of the TTV1 virus from Thermoproteus tenax. Part III: Immunological identification of the protein with anti-peptide antibodies.

To assess the expression of an hypothetical protein F154 encoded in an open reading frame of the DNA sequence of the virus TTV1 identified in the archaebacterium Thermoproteus tenax, two synthetic peptides related to characteristic repeats of the primary structure and corresponding to the sequence portions [Ser81] (73-84) and (79-101) were selectively grafted at their N-termini to the surface-exposed single cysteine residue of iso-1-cytochrome c via the maleimide thiol principle. Antisera were raised in rabbits against the two conjugates and the antipeptide-(79-101) immunoselected antibodies were found to crossreact with a strong protein band in Western blots of cell lysates of TTV1-infected bacteria, thus confirming expression of the protein F154 in Thermoproteus tenax.