无细胞系统

Cell-free system

无细胞系统

来源于细胞，不具有完整细胞结构，但包含进行正常生物学反应所需的物质组成的系统。

无细胞系统 cell-free system 指保留蛋白质生物合成能力的细胞抽取物。无细胞系统要包含以下成分：核糖体、各种tRNA、各种氨酰-tRNA合成酶、蛋白质合成需要的起始因子和延伸因子以及终止释放因子、GTP、ATP、20种基本的氨基酸。常见的无细胞翻译系统有：大肠杆菌无细胞翻译系统、兔网织红细胞无细胞翻译系统、麦胚无细胞翻译系统和某些肿瘤细胞制备成的无细胞翻译系统。

A cell-free preparation of the cytoplasm from activated eggs of Rana pipiens induces, in d emembranated sperm nuclei of Xenopus laevis非洲爪蟾, formation of a nuclear envelope核膜, chromatin decondensation染色质解凝, initiation of DNA synthesis, and chromosome con densation染色体凝缩. Both soluble可溶的and particulate微粒的cytoplasmic constituents细胞质成分are required to initiate these processes in vitro. The observed changes resemble proces ses occurring during fertilization and the mitotic cycle in early amphibian两栖动物embry os. Therefore, this cell-free system may be useful in biochemical analysis of the interactio ns相互作用of nucleus and cytoplasm that control nuclear behavior

A cell-free system is an in vitro tool widely used to study biological reactions that happen within cells while reducing the complex interactions found in a whole cell. Subcellular fractions can be isolated by ultracentrifugation超速离心法to provide molecular machinery that can be used in reactions in the absence of many of the other cellular components.

Cell-free biosystems生物系统are proposed as a new low-cost biomanufacturing 生物制造platform compared to microbial fermentation 发酵used for thousands of years. Cell-free biosystems have several advantages suitable in industrial applications.工厂应用[1]

1 First, in vitro biosystems can be easily controlled and accessed without membranes.

Cell-free protein synthesis is becoming a new alternative choice for fast protein synthesis.

2 Second, very high product yields are usually accomplished without the formation of

by-products or the synthesis of cell mass. For example, nearly 12 H2 has been produced per glucose unit of polysaccharides 多糖and water, three times of the theoretical 理论上的yield of the best anaerobic hydrogen-producing microorganisms.

3 Third, in vitro biosystems can implement some biological reactions that living microbes微生物or chemical catalysts化学催化剂cannot implement 实施，执行before. For example, beta-1,4-glucosidic bond linked cellulose can be converted to alpha-1,4-glucosidic bond linked starch by a mixture of intracellular and extracellular enzymes in one pot.

4 Fourth, enzymatic systems without the barrier of cellular membrane usually have faster reaction rates than microbial systems. For instant, enzymatic fuel cells usually have much higher power outputs than microbial fuel cells.