A simple and accurate high-performance liquid chromatography（HPLC）method to generate the fingerprints of crude Pu-erh tea（CPT）and ripened Pu-erh tea（RPT）is described.A suitable chromatographic system was establi...A simple and accurate high-performance liquid chromatography（HPLC）method to generate the fingerprints of crude Pu-erh tea（CPT）and ripened Pu-erh tea（RPT）is described.A suitable chromatographic system was established using a linear gradient elution with acetonitrile and water containing 0.6% formic acid as the mobile phase and a detection wavelength of 300 nm.HPLC analysis identified 24 common peaks among RPT and 21 common peaks among CPT.This study revealed that crude Pu-erh tea and ripened Pu-erh tea contained some similar major constituents,but with distinctive peaks,which may be caused by the difference in the fermentation process.This HPLC fingerprint method could be used to evaluate and authenticate crude Pu-erh tea and ripened Pu-erh tea.展开更多
文摘极端环境微生物是发掘性能优良新酶的重要资源,其中高稳定性的酶类在工业生产中具有巨大的潜在应用价值。该研究通过异源重组表达了嗜热玫瑰红球菌(Thermomicrobium roseum DSM 5159)来源的一段预测谷氨酰胺酶基因,并对其酶学性质进行了研究。利用镍柱亲和层析纯化表达产物,通过基质辅助激光解吸电离飞行时间质谱(matrix-assisted laser desorption/ionization time of flight mass spectrometry,MALDI-TOF-MS)鉴定纯化结果,分析了重组酶的催化功能,以正交试验优化了表达条件,考察了重组酶的酶学性质。结果表明,重组谷氨酰胺酶的二级结构由35.78%α-螺旋,14.07%β-折叠,16.06%β-转角以及34.19%无规则卷曲组成,热变性温度(T_(m))和变性焓(ΔH)分别为94.38℃和1672 kJ/mol,以L-谷氨酰胺为底物时,最适反应温度为70℃,最适反应pH值为9.0,70℃以下酶活力半衰期大于12 h,其耐热性能良好,动力学研究表明重组谷氨酰胺酶对L-谷氨酰胺的亲和力高于D-谷氨酰胺,Mn^(2+)、Fe^(2+)、Zn^(2+)、Cu^(2+)、Co^(2+)对酶活力有明显抑制作用。对嗜热古生菌来源的谷氨酰胺酶的结构及酶学性质的研究为挖掘开发具有优良热稳定性的工业生产用酶类提供了一定的参考价值。
基金"Study on the Active Components and Healthcare Function of Pu-erh Tea"(2007BAD58B04-2)"National Tea Industrial Science and Technology System"from Modern Agriculture Industrial Technology System,Yunnan Agricultural University
文摘A simple and accurate high-performance liquid chromatography（HPLC）method to generate the fingerprints of crude Pu-erh tea（CPT）and ripened Pu-erh tea（RPT）is described.A suitable chromatographic system was established using a linear gradient elution with acetonitrile and water containing 0.6% formic acid as the mobile phase and a detection wavelength of 300 nm.HPLC analysis identified 24 common peaks among RPT and 21 common peaks among CPT.This study revealed that crude Pu-erh tea and ripened Pu-erh tea contained some similar major constituents,but with distinctive peaks,which may be caused by the difference in the fermentation process.This HPLC fingerprint method could be used to evaluate and authenticate crude Pu-erh tea and ripened Pu-erh tea.
