私密直播全婐app免费大渔直播,国产av成人无码免费视频,男女同房做爰全过程高潮,国产精品自产拍在线观看

當前位置: 首頁 >> 產業發展 >> 正文

Evidence for organization of polymer chains in native polyhydroxyalkanoate granules

時間:2004-12-07
關鍵詞:Evidence organization polymer chains native polyhydroxyalkanoate granules 來源:International Symposium on Biological Polyesters ,Auguest 22-27, 2004

 

K. Sudesh1,*, Y. M. Normi1,2, Y. Kikawa2, Z. Gan3, K. Matsumoto2, T. Hiraishi2, and Y. Doi2,4

 

1            School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, MALAYSIA

2            Polymer Chemistry Laboratory, RIKEN Institute, Hirosawa 2-1, Wako-shi, 351-0198, Saitama, JAPAN

3            CAS Key Laboratory of Engineering Plastics, Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, CHINA

4            Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, JAPAN.

 

Keywords: polyhydroxyalkanoate, granule, AFM, polymer chain, fibril

 

      The most intriguing aspect of poly(3-hydroxybutyrate) (PHB) is its native structure in life bacterial cells. PHB is stored in cell cytoplasm as discrete water insoluble granules. Upon purification from cellular materials, PHB is a solid exhibiting almost 70% crystallinity. In vivo however, PHB is maintained in an amorphous mobile form, which is the only form accessible to the intracellular depolymerase enzymes. It is thus of paramount importance to prevent crystallization of PHB granules in vivo. How bacteria manage to achieve this has long been debated. The involvement of effective plasticizing agents has been proposed. In addition, other unknown mechanisms were thought to be involved to prevent PHB crystallization in vivo. At present, it is generally accepted that PHB granules in vivo remain amorphous simply because of slow nucleation kinetics that are operative for small particles. We have recently provided direct evidence for the existence of highly organized PHB chains in the form of fibrillar aggregates in the native granules. Here we provide further evidence by observing the initial stages of polymerization. We have successfully observed by using atomic force microscopy the formation of PHB chains in vitro. For this we have used purified PHB synthase. Before the addition of the substrate, R-3-hydroxybutyryl-CoA, the enzyme existed mainly as single subunits. Upon the addition of substrate, the enzyme formed complexes that were frequently associated with fibrillar structures. The synthesis and organization of the polymer chains into fibrillar structures occurred simultaneously. Of particular importance is the finding that both ends of a growing polymer chain were attached to the PHB synthase complex. We propose that this fibrillar organization is important to prevent crystallization and maintain the polymer chains in an amorphous/mobile state. Water molecules may be involved in the organization of the polymer chains. We believe that we have finally revealed the actual mechanism used by bacteria to prevent PHB crystallisation in vivo.

      論文來源:International Symposium on Biological Polyesters ,Auguest 22-27, 2004

主站蜘蛛池模板: 怀远县| 平定县| 绥棱县| 武平县| 当雄县| 彰化市| 青海省| 新河县| 开江县| 泾源县| 三门峡市| 当雄县| 佛学| 漯河市| 巴楚县| 攀枝花市| 惠水县| 太康县| 石楼县| 土默特左旗| 滁州市| 肃南| 开平市| 晋江市| 集安市| 伊通| 称多县| 丁青县| 泉州市| 六盘水市| 屏南县| 延川县| 临洮县| 都兰县| 灵石县| 贵港市| 道真| 莆田市| 南溪县| 阿图什市| 浙江省|