I. The Apparent Acid Dissociation Constants of Phenylalanine and Some of its Nuclearly Substituted Derivatives. II. The Isolation of Sphingosine from Bovine Spinal Cord. III. The Ultraviolet Absorption of Some O-Benzoyl Compounds

I. Apparent dissociation constants for the following compounds were determined by electrometric titration or ultraviolet spectroscopy: phenylalanine, ortho-, meta-, and parachloro-phenylalanines, para-sulfamido-phenylalanine, benzene sulfonamide, toluene sulfonamide, and methane sulfonamide. II. The basic hydrolysis of sphingolipids to obtain sphingosine and psychosine was investigated, using both liquid ammonia and anhydrous hydrazine. Dilituric acid was found to be an excellent reagent for the precipitation of the sphingosine bases. The presence of dihydrosphingosine in bovine spinal cord was confirmed by isolation of the tribenzoyl derivative. The ultraviolet light extinction curve of this derivative was determined in ethanol. III. The ultraviolet light extinction curves of methyl benzoate, "n-Octadecyl" benzoate, d, 1-di benzoyl n-octadecandiol-1,2, and benzoic anhydride were determined in hexane and those of the first and third compounds in ethanol.</p

脂質の薄層クロマトグラフィーで観察された二・三の幾何学的効果

最近脂質の生化学的研究において,薄層クロマトグラフィー(TLC)を用いた成分の定性・定量的および放射能の分布測定が重要な分析手段となっている.本報では脂質の成分クラスの分離に関し,TLCに応用可能な図形の検討を行なった. 一般に用いられている長方形のTLCと比較し,梯形・逆梯形あるいはダイヤモンド形TLCチャンネルにおいて,複雑な脂質混合系のある成分をよりよく分離検出することができた.このことはTLC上で観察されたRf値およびラジオ薄層クロマトグラムのスキャンニングによる放射活性ピークの検出数から明らかであった. これらのTLCでみられる幾何学的効果は,異なる図形へ流れ込む溶媒の量と方向性によって,定性的に説明されることを考察した.Some components of complex lipid mixtures were resolved better in trapezoidal, reverse trapezoidal, or diamond-shaped channels than in the usual rectangular TLC channel. This superiority was apparent from both the observed Rf values and the increased number of radioactive peaks detected by scanning. The results are explained qualitatively in terms of the amount and direction of solvent flow in the different configurations.This work was supported by a grant from the Ministry of Education of Japan (to MK) and by Contract AT (04-1) GEN-12 between the U. S. Atomic Energy Commission and the University of California (to JCN)

Tailoring the composition of novel wax esters in the seeds of transgenic Camelina sativa through systematic metabolic engineering

The functional characterization of wax biosynthetic enzymes in transgenic plants has opened the possibility of producing tailored wax esters (WEs) in the seeds of a suitable host crop. In this study, in addition to systematically evaluating a panel of WE biosynthetic activities, we have also modulated the acyl‐CoA substrate pool, through the co‐expression of acyl‐ACP thioesterases, to direct the accumulation of medium‐chain fatty acids. Using this combinatorial approach, we determined the additive contribution of both the varied acyl‐CoA pool and biosynthetic enzyme substrate specificity to the accumulation of non‐native WEs in the seeds of transgenic Camelina plants. A total of fourteen constructs were prepared containing selected FAR and WS genes in combination with an acyl‐ACP thioesterase. All enzyme combinations led to the successful production of wax esters, of differing compositions. The impact of acyl‐CoA thioesterase expression on wax ester accumulation varied depending on the substrate specificity of the WS. Hence, co‐expression of acyl‐ACP thioesterases with Marinobacter hydrocarbonoclasticus WS and Marinobacter aquaeolei FAR resulted in the production of WEs with reduced chain lengths, whereas the co‐expression of the same acyl‐ACP thioesterases in combination with Mus musculus WS and M. aquaeolei FAR had little impact on the overall final wax composition. This was despite substantial remodelling of the acyl‐CoA pool, suggesting that these substrates were not efficiently incorporated into WEs. These results indicate that modification of the substrate pool requires careful selection of the WS and FAR activities for the successful high accumulation of these novel wax ester species in Camelina seeds

The isolation and analysis of polyuronide materials from the barrel cacus, Echinocactus wislizenii

This item was digitized from a paper original and/or a microfilm copy. If you need higher-resolution images for any content in this item, please contact us at [email protected]