Acta chemica Scandinavica (Copenhagen, Denmark : 1989)最新文献_第6页

Nuclear magnetic resonance studies of thyrotropin-releasing hormone (TRH) and analogues incorporating D-histidine and 4-hydroxy-L-proline. 核磁共振研究促甲状腺激素释放激素(TRH)和含有d -组氨酸和4-羟基- l -脯氨酸的类似物。

Acta chemica Scandinavica (Copenhagen, Denmark : 1989) Pub Date : 1996-05-01 DOI: 10.3891/acta.chem.scand.50-0411

D W Aksnes, C Athanassopoulos, V Magafa, A Aaberg, G W Francis, D Papaioannou

引用次数: 3

Nickel-catalyzed oxidations: from hydrocarbons to DNA. 镍催化氧化:从碳氢化合物到DNA。

Acta chemica Scandinavica (Copenhagen, Denmark : 1989) Pub Date : 1996-04-01 DOI: 10.3891/acta.chem.scand.50-0337

C J Burrows, J G Muller, G T Poulter, S E Rokita

{"title":"Nickel-catalyzed oxidations: from hydrocarbons to DNA.","authors":"C J Burrows, J G Muller, G T Poulter, S E Rokita","doi":"10.3891/acta.chem.scand.50-0337","DOIUrl":"https://doi.org/10.3891/acta.chem.scand.50-0337","url":null,"abstract":"Nickel(II) complexes of tetradentate ligands such as cyclam and salen are catalysts for olefin epoxidation using PhIO and NaOCl, respectively. In order to understand the lack of enantioselectivity observed with chiral cyclam and salen complexes, studies of DNA and RNA oxidation were carried out in which evidence for diffusible oxidants might be found. A variety of square-planar, tetradentate nickel(II) complexes were observed to mediate guanine-specific modification in the presence of KHSO5 or magnesium monoperphthalate. In particular, the cationic complex, [(2,12-dimethyl-3,7,11,17-tetraazabicyclo [11.3.1]heptadeca-1(17),2,11,13,15-pentaenato)nickel]2+, [NiCR]2+, has been studied as a probe of nucleic acid folding. The extent of guanine reaction depends upon the exposure of N7, a good transition metal binding site, thus implicating nickel-guanine binding during DNA oxidation. If this is the case, related systems should be able to confer enantioselectivity during the use of chiral nickel complexes and achiral substrates for oxidation. Mechanistic studies, including radical quenching and DNA enantioselectivity, are described and their mechanistic implications discussed.","PeriodicalId":76966,"journal":{"name":"Acta chemica Scandinavica (Copenhagen, Denmark : 1989)","volume":"50 4","pages":"337-44"},"PeriodicalIF":0.0,"publicationDate":"1996-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19616982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 36

Antibody catalysis of pericyclic reactions. 抗体催化周环反应。

Acta chemica Scandinavica (Copenhagen, Denmark : 1989) Pub Date : 1996-04-01 DOI: 10.3891/acta.chem.scand.50-0328

H D Ulrich, E M Driggers, P G Schultz

引用次数: 11

Antibody catalysis via strategic use of haptenic charge. 通过战略性地使用半抗原电荷进行抗体催化。

Acta chemica Scandinavica (Copenhagen, Denmark : 1989) Pub Date : 1996-04-01 DOI: 10.3891/acta.chem.scand.50-0333

K Kikuchi, D Hilvert

引用次数: 4

Chemoenzymatic synthesis: application to the study of carbohydrate recognition. 化学酶合成:在碳水化合物识别研究中的应用。

Acta chemica Scandinavica (Copenhagen, Denmark : 1989) Pub Date : 1996-03-01 DOI: 10.3891/acta.chem.scand.50-0211

C H Wong

引用次数: 8

Stereochemical aspects of fatty acid oxidation: hydroperoxide isomerases. 脂肪酸氧化的立体化学方面:氢过氧化物异构酶。

Acta chemica Scandinavica (Copenhagen, Denmark : 1989) Pub Date : 1996-03-01 DOI: 10.3891/acta.chem.scand.50-0219

M Hamberg

{"title":"Stereochemical aspects of fatty acid oxidation: hydroperoxide isomerases.","authors":"M Hamberg","doi":"10.3891/acta.chem.scand.50-0219","DOIUrl":"https://doi.org/10.3891/acta.chem.scand.50-0219","url":null,"abstract":"Lipoxygenases catalyze dioxygenation of polyunsaturated fatty acids to produce fatty-acid hydroperoxides. The reaction involves initial stereospecific abstraction of a hydrogen atom from a bis-allylic methylene group followed by antarafacial attack by dioxygen at one of the terminal carbon atoms of the pentadienyl radical. 8(R)-Dioxygenase, recently discovered in the fungus Gaeumannomyces graminis, catalyzes formation of 8-hydroperoxy derivatives of linoleic and oleic acids by abstracting one hydrogen from C-8 and inserting dioxygen at the same carbon atom. Isotope-labeling studies show that the configuration at C-8 is inverted during this process. The fungus Saprolegnia parasitica, a fish parasite, contains an omega 6-lipoxygenase and an epoxy alcohol synthase. The latter enzyme catalyzes isomerization of fatty acid hydroperoxides into alpha,beta- and gamma,delta-epoxy alcohols. Experiments with 18O-labelled hydroperoxides demonstrate that the hydroperoxide --> epoxy alcohol conversion consists of intramolecular transfer of the terminal hydroperoxide oxygen to either of the two conjugated double bonds. The reactions proceed with retention of geometrical configuration, i.e. epoxidation of the alpha,beta (E) and gamma,delta (Z) double bonds of the parent fatty acid hydroperoxide gives rise to trans and cis epoxides, respectively. G. graminis, as well as the marine red alga Gracilariopsis lemaneiformis, contain vicinal diol synthases that catalyze isomerization of fatty-acid hydroperoxides into vicinal dihydroxy fatty acids. Studies using 18O-labelled hydroperoxides show that the hydroperoxide --> diol conversions occur by intramolecular transfer of the terminal hydroperoxide oxygen to the vicinal methylene group. Experiments with stereospecifically deuteriated fatty-acid hydroperoxides demonstrate that the intramolecular hydroxylations catalyzed by the two vicinal diol synthases proceed with retention of absolute configuration of the carbon hydroxylated.","PeriodicalId":76966,"journal":{"name":"Acta chemica Scandinavica (Copenhagen, Denmark : 1989)","volume":"50 3","pages":"219-24"},"PeriodicalIF":0.0,"publicationDate":"1996-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19867363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 17

The potential of catalytic antibodies. 催化抗体的潜力。

Acta chemica Scandinavica (Copenhagen, Denmark : 1989) Pub Date : 1996-03-01 DOI: 10.3891/acta.chem.scand.50-0203

A J Kirby

引用次数: 36

pH and ionic strength effects on electron transfer rate constants and reduction potentials of the bacterial di-heme protein Pseudomonas stutzeri cytochrome c4. pH和离子强度对细菌二血红素蛋白stutzeri假单胞菌细胞色素c4的电子传递速率常数和还原电位的影响。

Acta chemica Scandinavica (Copenhagen, Denmark : 1989) Pub Date : 1996-03-01 DOI: 10.3891/acta.chem.scand.50-0284

J J Karlsson, T E Rostrup, J Ulstrup

{"title":"pH and ionic strength effects on electron transfer rate constants and reduction potentials of the bacterial di-heme protein Pseudomonas stutzeri cytochrome c4.","authors":"J J Karlsson, T E Rostrup, J Ulstrup","doi":"10.3891/acta.chem.scand.50-0284","DOIUrl":"https://doi.org/10.3891/acta.chem.scand.50-0284","url":null,"abstract":"We have investigated the ionic strength (0.1-0.5 M NaCl) and pH dependence (4.0-7.5) of the electron transfer (ET) rate constants for oxidation and reduction of the bacterial di-heme protein cytochrome c4 (cyt c4; Pseudomonas stutzeri, ATCC No. 11607) by [Co(bipy)3]3+/2+ (bipy = 2,2'-bipyridine). The kinetics is bi- or tri-phasic, and a mechanism based on cooperative ET at both hemes, slow intramolecular ET and electrostatically dominated inter-heme interaction is presently best in line with all the available data. The ionic strength and pH dependence of the rate constants and reduction potentials is weak. The rate constants mostly decrease by 0-50% in the ionic strength range 0.1-0.5 M. The macroscopic potentials decrease by < 10 mV. Three of the microscopic potentials increase by 10-25 mV, while the fourth one decreases by 50 mV, but the accuracy of the microscopic reduction potential values is low. There is no pH dependence of the rate constants in the range 6.0-7.5, but most rate constants drop to half the 6.0-7.5 value in the range 4.0-6.0, leaving the reduction potentials almost unaffected. The small effects are unexpected in view of the highly charged and strongly dipolar character, and the many hydrogen bond contacts of cyt c4. These small effects must be related to the detailed rather the overall charge distribution of cyt c4.","PeriodicalId":76966,"journal":{"name":"Acta chemica Scandinavica (Copenhagen, Denmark : 1989)","volume":"50 3","pages":"284-8"},"PeriodicalIF":0.0,"publicationDate":"1996-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19866028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 9

Developing new synthetic catalysts. How nature does it. 开发新型合成催化剂。大自然是如何做到的。

Acta chemica Scandinavica (Copenhagen, Denmark : 1989) Pub Date : 1996-03-01 DOI: 10.3891/acta.chem.scand.50-0243

S A Benner, T M Jermann, J G Opitz, S A Raillard, T R Zankel, K Trautwein-Fritz, J Stackhouse, M I Ciglic, M Haugg, N Trabesinger-Rüf, E G Weinhold

引用次数: 4

Synthesis and 5HT modulating activity of stereoisomers of 3-phenoxymethyl-4-phenylpiperidines. 3-苯氧甲基-4-苯基哌啶立体异构体的合成及5HT调控活性。

Acta chemica Scandinavica (Copenhagen, Denmark : 1989) Pub Date : 1996-02-01 DOI: 10.3891/acta.chem.scand.50-0164

M Engelstoft, J B Hansen

引用次数: 19