A novel ionic polymer, poly(1,1,3,3-tetramethylguanidine acrylate) (PTMGA), was synthesized, and its SO 2 absorption and desorption properties were studied for the first time. 1,1,3,3-Tetramethylguanidine acrylate, a polymerizable ionic liquid (IL), was first prepared via neutralization of 1,1,3,3-tetramethylguanidine and acrylic acid. PTMGA was then synthesized via free radical polymerization of TMGA. The polymer adsorbed SO 2 with high selectivity, capacity, and rate. The absorption capacity and rate of PTMGA were significantly higher than the monomer. The SO 2 absorbed at a relatively low temperature was effectively desorbed at higher temperatures and/or under vacuum. The absorption/desorption process could be repeatedly operated, and thus the polymer was reused. Under a typical operation condition, about 0.3 g of SO 2 per gram of polymer was separated in each cycle. The PTMGA material showed a good potential as solid-state SO 2 absorbent for applications in purification of SO 2 -containing gas such as fuel gas desulfurization.

We have probed Pichia stipitis CBS 6054 Old Yellow Enzyme 2.6 (OYE 2.6) by several strategies including X‐ray crystallography, ligand binding and catalytic assays using the wild‐type as well as libraries of site‐saturation mutants. The alkene reductase crystallized in space group P 63 2 2 with unit cell dimensions of 127.1×123.4 Å and its structure was solved to 1.5 Å resolution by molecular replacement. The protein environment surrounding the flavin mononucleotide (FMN) cofactor was very similar to those of other OYE superfamily members; however, differences in the putative substrate binding site were also observed. Substrate analog complexes were analyzed by both UV‐Vis titration and X‐ray crystallography to provide information on possible substrate binding interactions. In addition, four active site residues were targeted for site saturation mutagenesis (Thr 35, Ile 113, His 188, His 191) and each library was tested against three representative Baylis–Hillman adducts. Thr 35 could be replaced by Ser with no change in activity; other amino acids (Ala, Cys, Leu, Met, Gln and Val) resulted in diminished catalytic efficiency. The Ile 113 replacement library yielded a range of catalytic activities, but had very little impact on stereoselectivity. Finally, the two His residues (188 and 191) were essentially intolerant of substitutions with the exception of the His 191 Asn mutant, which did show significant catalytic ability. Structural comparisons between OYE 2.6 and Saccharomyces pastorianus OYE1 suggest that the key interactions between the substrate hydroxymethyl groups and the side‐chain of Thr 35 and/or Tyr 78 play an important role in making OYE 2.6 an (S)‐selective alkene reductase.

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