The ultraviolet and visible absorption spectra of laser-induced transient species from the following pyrene derivatives were measured in aqueous or aqueous ethanol solution: sodium pyrenesulfonate (NaPS), tetrasodium pyrenetetrasulfonate (Na 4 PS 4 ), pyrenecarboxylic acid (HPC), and pyrenebutyric acid (HPB). The major transient species contributing to the intense absorption peaks were revealed on the basis of the quenching experiments. The absorption spectra of triplets, as well as cation radicals, were separable from the other transients by selecting the experimental conditions (atmosphere, coexisting quencher, and delay time). The cation radicals produced from PS -, PBand PCanions showed an absorption maximum at ∼460 nm, close to that of pyrene cation radical. Their decay behaviors in the absence of any additional quenchers were dominated by bimolecular reaction kinetics with each parent molecule, of which the rate constants were very similar. This result is consistent with the previous proposal that these cation radicals exist as zwitterions such as P •+ S -. The cation radical from Na 4 PS 4 showed a strong absorption peak at 505 nm and exhibited different decay behaviors, suggesting that this cation radical appears not to be a simple zwitterion. Three specific quenchers, I -, OH -, and SO 3 2-, were found to strongly accelerate the decay rates of these cation radicals. CH 3 SO 3anion, mimicking the headgroup of tentative anionic surfactants, and several inorganic anions such as ClO 4were poor quenchers for the cation radicals even at the highest concentration. We also discussed the origin of two additional peaks at 375 and 395 nm observed in the transient absorption spectra of NaPS and HPB. On the triplet-triplet absorption, the molar extinction coefficients of Na 4 PS 4 and NaPS could be determined using the ground-state depletion method. These results are discussed in terms of applications to probe the micellar microenvironment.

Page 14327. Figure 4A shows the side chain of Lys262 (NζH 3 ) also salt linked to an oxygen of the pyrophosphate of the NADPH cofactor. This should, as in the ALR2 structure [Wilson et al. (1992) Science 257, 81-84], appear as the backbone peptide NH of the lysine hydrogen bonded to that same oxygen. BI9550253 1700

Since IL-10 has recently been shown to exhibit pleiotropic effects on human monocytes, it was of interest to determine the effect of this cytokine on prostaglandin E2 (PGE2) production by monocytes. Recombinant IL-10 (rIL-10) did not significantly affect PGE2 production by lipopolysaccharide (LPS)-unstimulated monocytes, but efficiently inhibited PGE2 production by LPS-stimulated monocytes. The inhibition by rIL-10 was achieved in a dose-dependent manner. Recombinant IL-4 also inhibited PGE2 production at the same degree as rIL-10. Viral IL-10 inhibited PGE2 production by monocytes in a similar fashion as did human rIL-10. Endogenously produced IL-10 was also shown to inhibit PGE2 production by LPS-stimulated monocytes. Kinetic studies showed that the inhibition by rIL-10 on PGE2 production was observed at least 3 h after LPS stimulation. Taken together, these results indicate that IL-10 may play an important role in modulating immunological responses via down-regulation of PGE2 production by monocytes.

No abstract

The blue copper proteins have been the focus of many spectroscopic and structural studies,1 with much of the interest centering on the nature of the copper site. X-ray crystallographic results have previously been reported for two single-copper proteins, plastocyanin and azurin. The structure of the oxidized, Cu(II),