γ-聚谷氨酸的微生物合成及应用

γ-聚谷氨酸是一种多功能、可降解的生物高分子,可由微生物发酵合成,近年来受到广泛关注。文章综述了γ-聚谷氨酸的化学结构、制备方法(重点是微生物发酵合成法)、产生菌及相应发酵条件、微生物合成γ-聚谷氨酸的分子机制及γ-聚谷氨酸在医药、食品、化妆品、农业、工业等方面的应用,并对γ-聚谷氨酸研究的发展前景作了展望。     

生物合成聚γ-谷氨酸的结构表征

通过红外光谱解析结合标准图谱对照,确定由生物发酵法制备的谷氨酸聚合物为聚γ 谷氨酸。再利用1H和13C高分辨魔角旋转核磁共振谱的化学位移特征及峰面积比确证了该聚合物的结构。利用对γ 谷氨酰键专一作用的γ 谷氨酰转肽酶酶解法分析该样品,证明了样品中γ 酰胺键的存在。通过以上的综合结构表征,证实COOHO所制备样品具有下列结构:CH NH。CH2CH2C     

γ-聚谷氨酸的生产及应用研究进展

综述了γ-PGA的生产方法以及其应用领域。γ-聚谷氨酸是由微生物合成的可降解的生物高分子。由于其水溶性好、可吸附重金属、及对人体和环境无毒,在医药、环境保护、农业和食品等领域具有广泛的应用前景。     

聚谷氨酸高吸水树脂的表征

对聚谷氨酸高吸水树脂进行了IR1、HNMR、热稳定性、吸水性能的分析,结果表明:在3 305 cm-1为O—H伸缩振动带,1 646 cm-1为羧基中—C O的伸缩振动带,1 593 cm-1为NH弯曲和C—N伸缩振动的偶合,1 111 cm-1为侧链脂肪醚C—O—C的非对称伸缩振动,2 876 cm-1为γ-PGA主链上—CH2的C—H键的对称伸缩振动;3.628处出现了聚乙醇缩水甘油醚上的H的化学位移,说明聚乙二醇缩水甘油醚与聚谷氨酸已充分交联;聚谷氨酸高吸水树脂具有良好的热稳定性及吸水性能。     

γ-聚谷氨酸乙酯与γ-聚谷氨酸苄酯的生物降解性能

为了了解生物可降解聚合物γ-聚谷氨酸（γ-PGA）乙酯与γ-聚谷氨酸苄酯的生物降解性能,采用枯草杆菌NX-2（Bacillus subtilis）、黑曲霉（Aspergillus niger）和土埋法对γ-PGA乙酯和γ-PGA苄酯的降解性能进行研究,用扫描电镜观察降解结果.结果表明：枯草杆菌对γ-PGA乙酯和γ-PGA苄酯的降解作用优于黑曲霉;相对厚度较大的薄膜,在枯草杆菌NX-2中缓慢降解;在黑曲霉中,γ-PGA乙酯的降解速率相对较慢,薄膜的形态没有发生变化;γ-PGA苄酯的降解性能优于γ-PGA乙酯.     

γ-聚谷氨酸改性技术及高附加值应用研究进展

γ-聚谷氨酸是一种经由微生物杆菌发酵合成的高分子材料,具有水溶性、吸水、保湿、生物可分解性,无毒、安全以及很强的生物适应性。γ-聚谷氨酸富含羟基和氨基,通过改性可以得到特定的功能高分子。综述了几种目前常用的γ-聚谷氨酸改性方法,以及目前国内外改性γ-聚谷氨酸在医用领域的高附加值应用概况。     

γ-聚谷氨酸的特性、生产及应用

γ-聚谷氨酸是-种谷氨酸同聚物,可由微生物发酵得到.γ-聚谷氨酸具有水溶性、可生物降解性和可食用性且对人和环境无毒的诸多优点,这使得γ-聚谷氨酸及其衍生物在食品、化妆品、医药和农业等领域具有广阔的应用前景.本文综述了γ-聚谷氨酸的化学结构、性质、生产方法及其用途.     

生物合成聚γ-谷氨酸的酯化改性国外研究进展

对国外生物合成聚γ 谷氨酸的各种酯化改性研究工作进行了较系统全面的总结 ,阐述了它们各自的特点     

生物合成聚γ-谷氨酸的相对分子质量表征

为了确定特定条件下聚γ 谷氨酸(γ PGA)水溶液的Mark Houwink方程参数,在参数适用范围内通过特性粘度测量,对γ PGA的相对分子质量进行快捷、可靠的估计,在对钠盐型γ PGA稀溶液的粘度特性和流变性质进行了系统考察的基础上,采用凝胶渗透色谱-激光光散射联机试验(GPC LLS)和粘度方法,研究了钠盐型γ PGA的特性粘数、分子尺寸对重均相对分子质量的依赖性;建立了γ PGA在1.20mol LNaCl水溶液中的Mark Houwink方程。提出了相对分子质量的测定方法,并对均方末端距进行了估算。较大的α值表明:γ PGA大分子即使在1.20mol L的离子强度下由于聚离子的静电相斥作用仍然在溶剂中呈现出较伸展的构象,即呈棒状结构。     

γ-聚谷氨酸及其在水处理中的应用

γ-聚谷氨酸是由微生物合成的可降解的水溶性的生物高分子,在水中分子链上有大量的带负电荷的羧基,可以作为生物絮凝剂吸附大量的阳离子。综述了γ-聚谷氨酸的构像在溶液中的变化以及其在水处理中的应用。     

Fabrication of ultrafine fibers of poly(γ-glutamic acid) and its derivative by electrospinning

Poly(γ-glutamic acid) (PGA) was successfully electrospun by the addition of poly(ethylene glycol) (PEG) and Triton X-100 in its aqueous solution to produce the PGA non-woven mat of the ultrafine fibers. The average fiber diameter was in the range between 200 nm and 2 μm. The fiber mat was quickly soluble in water due to the large surface area of the fibers. The electrospinning of PGA butyl ester with the esterification degree of 61% in 1,1,1,3,3,3-hexafluoro-2-propanol gave the water-insoluble nanofiber mat.     

Poly(γ-glutamic acid) hydrogel prepared from microbial poly(γ-glutamic acid) and alkanediamine with water-soluble carbodiimide

Poly(γ-glutamic acid) (PGA) hydrogels have been prepared from microbial PGA produced by Bacillus subtilis F-02-1, water-soluble carbodiimide (WSC), and alkanediamines such as 1,3-propanediamine (1,3-PD), 1,4-butanediamine (1,4-BD), and 1,6-hexanediamine (1,6-HD) in aqueous medium. The carboxyl groups of PGA were activated by the addition of WSC in deionized water, and the PGA-WSC adduct was produced. PGA hydrogels could be produced after the mixing of PGA-WSC and alkanediamine in deionized water. This alkanediamine to which both amino groups reacted with the carboxyl groups of PGA plays the role of a crosslinking point. When the amount of PGA was 100 mg, WSC was 50 mg or more, and 1,3-PD was 25 μL or more in 2 mL of deionized water, PGA hydrogels could be produced. Specific water contents (weight of absorbed water/weight of dry gel) ranged from 300 to 1,993 g/g in the case of 1,3-PD. If the PGA-WSC adduct was freeze-dried, the yield of the PGA hydrogel became higher than that when PGA-WSC was not freeze-dried. The highest yield of the PGA hydrogel from 100 mg of PGA, 100 mg of WSC, and 100 μL of 1,3-PD in 2 mL of deionized water using the freeze-dry method was 39.9 mg of dry PGA hydrogel with a 650 g/g specific water content. The order of yield was 1,6-HD > 1,4-BD > 1,3-PD from 100 mg of PGA-100 mg of WSC in 2 mL of deionized water. The order of the specific water content was 1,3-PD (462 g/g) > 1,4-BD (234 g/g) > 1,6-HD (199 g/g). This order may be due to the higher reaction probability between the activated carboxyl groups in the PGA-WSC and both amino groups in the alkanediamine with longer methylene chains, indicating that the crosslinking density of the PGA hydrogel is higher and the specific water content is lower. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 1889–1896, 1997     

聚丙烯酸-聚(γ-苄基-L-谷氨酸酯)接枝共聚物的合成与表征

采用溶液聚合法直接合成聚丙烯酸(PAA),通过接枝反应合成了新型两亲性PAA-聚(γ-苄基-L-谷氨酸酯)(PBLG)接枝共聚物,分析了PAA与PBLG的相对分子质量及结构,并通过1H-核磁共振(1H-NMR)、红外光谱(IR)对共聚物进行了表征。结果表明,随着引发剂偶氮二异丁腈用量的增加或聚合温度的升高,PAA的数均相对分子质量减小;随着引发剂正丁胺用量的增加,PBLG的黏均相对分子质量减小。共聚物中含有接枝到PAA链上的疏水性PBLG,同时还含有未反应的亲水性羧基;共聚物在NaCl或NaOH水溶液中形成的球形胶束具有明显的核壳结构。     

聚(L-谷氨酸-γ-苯甲酯)接枝共聚物的合成

以溶液聚合直接合成聚丙烯酸,通过接枝反应将疏水的聚肽链接到聚丙烯酸亲水链段上形成两亲性共聚物,合成了新型聚肽接枝共聚物。用核磁共振等方法表征了接枝共聚物的存在。实验结果表明其在含有钠离子的水溶液中能自行组装成为高聚物纳米胶束。     

聚乳酸的合成及应用

综合分析了聚乳酸的合成方法和应用概况,重点阐述了间接开环聚合的机理,以及直接缩聚反应提高聚乳酸分子质量的最新进展概况。对聚乳酸的应用现状及应用前景进行了归纳分析,提出了聚乳酸研究的发展方向及重点应用领域。     

Synthesis and characterization of three-branched star-like poly(γ-benzyl-l-glutamate)

Summary Three branched star-like poly(-benzyl-l-glutamate) was synthesized using three functional amine as an initiator, and characterized through light-scattering, ORD and intrinsic viscosity measurements. Experimental results suggest that the synthesized star-like poly(-benzyl-l-glutamate)s are composed of three branches of equal length.     

Molecular motion in poly(amino acid)s: 6. Molecular motion in a β-form crystal of poly(γ-methyl-d-glutamate)

The molecular motion in a β-form crystal of fully annealed poly(γ-methyl-d-glutamate) was investigated by means of an X-ray diffractometer and an infra-red spectrophotometer. The interchain periodicity (chains are bound side by side with intermolecular hydrogen bonds) increases linearly with increasing temperature, indicating ordinary thermal expansion of the lattice. The intersheet periodicty (sided chains pack into sheets) increases linearly up to 150°C and then the slope of the temperature dependence of the periodicty increases owing to the onset of active segmental motion of the side chains.It is evident from the temperature dependence of the wavenumber of the maximum of the infra-red absorption for NH stretching in the crystal that thermal expansion in the direction of the hydrogen bond is hardly affected by the segmental motion of the side chain.     

聚乳酸及其纤维的发展概况和应用前景

介绍了聚乳酸及其纤维的发展现状,纺丝成型及纤维的性能和主要应用领域。由于聚乳酸纤维采用了天然可再生的植物资源,使用后可自然降解,所以在纺织、医学、农业等领域都有广阔的发展前景。