Short communication: Application of proteomics for characterization of caseinomacropeptide isoforms before and after desialidation

Caseinomacropeptide (CMP) is an important polypeptide found in cheese whey that has various biological activities and functional properties. Because sialylations play an important role in the functional properties of CMP, the aim of the present work was to characterize CMP isoform heterogeneity in a commercial glycosylated CMP (gCMP) isolate using liquid chromatography– and gel-based proteomics before and after desialidation. Using 2-dimensional gel electrophoresis (2-DGE), we observed a shift in isoelectric point (pI) after enzymatic desialidation, indicating that sialylated gCMP were located at pI 3.0 to 3.1, but desialylated gCMP had repositioned to pI 3.7 to 3.9. We used liquid chromatography/mass spectroscopy (LC-ESI/MS) for further analysis of the glycan chains of gCMP. In total, we identified 19 CMP isoforms, of which 13 were glycosylated and 6 were nonglycosylated. We also detected 3 genetic variants (A, B, and E), with up to 3 glycosylations attached per gCMP. Further, we identified up to 4 isomers, reflecting different sites of glycosylation in the peptide backbone of these isoforms. The dominating gCMP isoform of genetic variant E appeared to contain 4 N-acetyl-neuraminic acid (NeuAc) residues, whereas the dominating gCMP isoforms of variants A and B appeared to contain 2 NeuAc. The identification revealed conversions of isoforms containing different combinations of genetic variants and degrees of glycosylation, sialylation, and phosphorylation to various desialylated counter-isoforms. The content of sialylated gCMP relative to the total CMP content was 37% (wt/wt), which decreased to 1.5% after sialidase treatment, indicating 96% effectivity of the desialidation. This approach can be valuable for future functionality studies specifically addressing the importance of NeuAc.     

The structure of the triacylglycerols,containing punicic acid,in the seed oil ofTrichosanthes kirilowii

Triacylglycerols of the seed oil ofTrichosanthes kirilowii have been resolved by high-performance liquid chromatography (HPLC) in the silver-ion and reverse-phase modes. The fatty acids were identified by gas chromatography/mass spectrometry as the picolinyl esters. The main components arecis,cis-C18:2n-6 (38.2 mole%), C18:3_9c,11t,13c (punicic acid, 38.0 mole%), andcis-C18:1n-9 (11.8 mole%). Small amounts of C18:3_9c,11t,13t (α-eleostearic acid) and C18:3_9t,11t,13c (catalpic acid) were detected. Silver-ion HPLC exhibited excellent resolution in which fractions were resolved on the basis of the number and configuration of double-bonds. In this instance, the strength of interaction of a conjugated trienoic double-bond system with silver ions seemed to be between that of dienoic and monoenoic double bond systems. The triacylglycerols were also separated into 20 fractions by reverse-phase HPLC, and the fractionation was achieved according to the partition number in which a conjugated trienoic double bond was not equivalent to three monoenoic double bonds in a molecule with a given chainlength. The principal triacylglycerol species are (C18:2n-6) (C18:3_9c,11t,13c )₂ (28.3 mol% of total), (C18:1n-9)(C18:2n-6) (C18: 3_9c,11t,13c ) (19.0 mol%), and (C18:2n-6)₂(C18:3_9c,11t,13c ) (16.2 mol%), while simple triacylglycerols such as (C18:3_9c11t,13c )₃ and (C18:2n-6)₃ were present as minor components only (<1.0 mol%). Species esterified with conjugated trienoic acids comprise more than 96% of the total. Stereospecific analysis gave rise to insurmountable difficulties, but it is evident that there is some asymmetry in the distribution of fatty acids in the molecules.     

虫草素类似物2’-脱氧腺苷脂质体的制备及表征

虫草素具有多种生物活性,通过与新型药物载体脂质体结合,可解决其临床中的脱氨基作用。2'-脱氧腺苷是虫草素的结构类似物,易制备,具有和虫草素相同的紫外最大吸收波长(259nm),是一种优良的虫草素替代品,研究2'-脱氧腺苷脂质体可为虫草素脂质体的研究提供重要的参考。本文采用逆相蒸发法制得球形、粒径170～350nm、包封率为45%、稳定性良好的2'-脱氧腺苷脂质体。为虫草素脂质体研究提供基础数据。     

高效液相色谱法分析脂肪醇聚氧乙烯醚产品的组分分布

使用 C8 和 C18键合硅胶色谱柱 ,示差折光检测器的反相液相色谱法研究了脂肪醇聚氧乙烯醚 ( AEO)产品的组分分布 ,通过优化流动相配比实现了对 AEO3 产品各组分同时按脂肪醇碳链长度和环氧乙烷加成数的分离。方法简便快速 ,适用于产品的质量控制和工艺开发。     

反相悬浮聚合法制备超强吸水树脂

以环己烷作为分散介质,以司班80作为分散荆,N,N-亚甲基双丙烯酰胺和多元醇作为交联剂,过硫酸铵作为引发剂采用反相悬浮聚合法分两阶段合成了核壳型超强吸水树脂,得到的产品呈颗粒状,吸去离子水倍率为998g／g,吸生理盐水的吸液倍率达到147g／g。探讨了分散荆、交联剂、反应温度、丙烯酸中和度及核壳比对超强吸水树脂物理状态及吸液能力的影响。     

A contribution to the study of the enantiomeric composition of a chiral constituent in hazelnut oil used in the detection of adulterated olive oil

 A method is proposed for the determination of the adulteration of olive oil with hazelnut oil which is based on the study of the enantiomeric makeup of (E)-5-methylhept-2-en-4-one (filbertone). The possibilities of either using a sample preparation technique or performing direct injection of the samples (i.e., without any kind of sample pretreatment) are considered and both simultaneous distillation extraction followed by gas chromatographic analysis and direct injection in on-line coupled reverse-phase liquid chromatography to gas chromatography are used. In both cases, a chiral stationary phase is employed in the gas chromatography step and the determination of the enantiomeric composition of filbertone is recommended for an accurate evaluation and quick control for detecting the adulteration of olive oil with hazelnut oil. Received: 9 October 1998 / Revised version: 22 March 1999     

油茶饼中茶皂素的定量分析

研究了用反相高效液相色谱法（HPLC）测定茶皂素含量的方法,以VP-ODS（250mm×4.6mm,C18,5μm）作分析柱,以甲醇-水-（v：v=9：1）作流动相,流速控制在1．0mL／min,检测波长280nm,以质量浓度为横坐标,峰面积为纵坐标,得到工作曲线为Y=3．02×10^6X-1．16×10^4,线性相关系数为0．9995。回收率为97．02％～102．82％。通过反相高效液相色谱法测定茶籽饼中粗茶皂素的含量为11．89％。     

The use of reverse-phase C18-bonded silica for the trapping,concentration and analysis of headspace vapour from model organic compounds,banana pseudostem and black pepper

A study of recovery efficiency of a series of volatile compounds trapped on reverse-phase C₁₈-bonded silica has shown that reverse-phase silica is a useful addition to the existing range of adsorbents available for headspace volatile concentration and analysis. A gas chromatograph comparison of the airborne volatiles from black pepper (Piper nigrum) and banana pseudostem (Musa sp) recovered from reverse-phase silica, activated charcoal and Porapak Q traps shows no qualitative differences in the components present.     

仙人掌SOD脂质体的制备研究

采用逆相蒸发法制备仙人掌SOD脂质体，最佳工艺为：卵磷脂与胆固醇的质量比为2：1，乙醚与SOD酶液的比为3：1，经超声乳化和旋转蒸发可制得包封率为56％的脂质体，包封后的SOD在胃蛋白酶的作用及高温下，比游离的SOD稳定。