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131.
Shiro Kobayashi Ryosuke Itoh Hidekazu Morii Shun-Ichi Fujikawa Shunsaku Kimura Masashi Ohmae 《Journal of polymer science. Part A, Polymer chemistry》2003,41(22):3541-3548
Hyaluronic acid and chondroitin were successfully synthesized as representative molecules of glucosaminoglycans and galactosaminoglycans found in a glycosaminoglycan family via enzymatic polymerization catalyzed by testicular hyaluronidases. A newly designed N-acetylhyalobiuronate oxazoline derivative with a β-D -glucuronyl-(1→3)-N-acetyl-D -glucosamine disaccharide structure served as a transition-state analogue substrate monomer for the enzyme, giving rise to artificial hyaluronic acid in 52% yields with a number-average molecular weight of 1.35 × 104 through ring-opening polyaddition in a perfect regioselective and stereoselective manner. A novel N-acetylchondrosine oxazoline derivative with a β-D -glucuronyl-(1→3)-N-acetyl-D -galactosamine disaccharide structure also acted as a transition-state analogue substrate monomer for the enzyme, yielding artificial chondroitin in 35% yields with a number-average molecular weight of 2.5 × 103. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3541–3548, 2003 相似文献
132.
Masashi Nakagawa Tatsuo Iwasa Satoshi Kikkawa Toshifumi Takao Yasutsugu Shimonishi Motoyuki Tsuda 《Photochemistry and photobiology》1997,65(1):187-191
Abstract— We determined the structure and site of fatty acid incorporated in octopus rhodopsin using a combination of fluorescence label and enzymatic cleavage methods in conjunction with fast-atom bombardment (FAB) mass spectrometry. A single peptide containing two adjacent cysteines, Cys337 and Cys338, was successfully isolated using the fluorescence from a dye conjugated to Cys345. The FAB mass spectrometric analysis of the peptide (323phe-340 phe) revealed that two palmitoyl groups are linked to Cys337 and Cys338 via thioester bonds in octopus rhodopsin as in bovine rhodopsin. 相似文献
133.
N-Alkyl-N(1-hydroperoxyalkyl)nitrosamines were synthesized from N,N-dialkylnitrosamines by lithiation with lithium diisopropylamide, followed by oxygenation with oxygen in good yields. 相似文献
134.
Xestospongin A,B,C and D represent a new class of macrocyclic 1-oxaquinolizidines, have been isolated from Australian sponge . The structure of xestospongin C has been determined by X-ray analysis. 相似文献
135.
Hideo Hiraia Kozo Sawada Matsuhiko Aratani Masashi Hashimoto 《Tetrahedron letters》1984,25(44):5075-5078
Aldol and alkylation reactions of the chiral 4-allylazetidinone 1 gave 3,4-trans-azetidinones as major products, in which 10 was converted in several steps to the optically active 6-epicarpetimycins 2. 相似文献
136.
Makoto Yanaga Kazutoyo Endo Toshio Shimizu Hiromichi Nakahara Masashi Takahashi Masuo Takeda 《Hyperfine Interactions》1994,90(1):499-503
A systematic study of pentavalent organoantimony compounds, (RC6H4)3SbX2 (R=H,p-CH3,p-F,p-Cl,p-CF3,o-CH3; X=Cl, Br), was carried out to examine the effect on Mössbauer parameters of the substituent on the aromatic ring. The Mössbauer parameters obtained in polycrystalline form reflected the steric effect caused by the position of the substituent on the aromatic ring. On the other hand, measurements in frozen organic solutions revealed that the electron density and electric field gradient at and around the antimony nucleus became smaller when the more electron-attractive group was introduced into thepara position. 相似文献
137.
Tadakatsu Mandai Masashi Yamaguchi Yuka Nakayama Junzo Otera Mikio Kawada 《Tetrahedron letters》1985,26(22):2675-2676
Development of a new synthetic method for α-ketosilanes can be achieved by a sequence of alkylation of methoxy(phenylthio)trialkylsilylmethane and oxidation with NaIO4. 相似文献
138.
The lowest excited nπ* triplet of 9.10-anthraquinone, 1.4-naphthoquinone and 1,4-benzoquinone were studied in glassy matrices at 77 K using a time-resolved ESR method. The D value of the triplet state of 9,10-anthraquinone varied from ?0.351 cm?1 in a polar solvent to ?0.318 cm?1 in a non-polar solvent. Both 1,4-naphthoquinone and 1,4-benzoquinone in polar solvents showed triplet state spectra with a D value of ?0.330 cm?1. A computer simulation revealed the existence of widely distributed zero-field splitting parameters in the glassy condition. These data are compared with an analysis of CIDEP results of para-quinones. 相似文献
139.
A new implementation of the Marquardt method for the nonlinear least-squares problem is presented. The algorithm is very simple but its performance with nine test functions is at least comparable with either Davidon-Fletcher-Powell's method or Moré's adaptive Marquardt method. 相似文献
140.