黑色素生物合成抑制剂的初步研究

利用比基尼链霉菌筛选模型和急性细胞毒性试验从 170 0株放线菌中筛选出编号为MBI 3 9-2 4的菌株作为黑色素生物合成抑制剂研究的试验菌株 ,并初步鉴定为秃裸链霉菌 (Streptomycescalvus)。借鉴了一些天然药物的提取和分离方法 ,分离出 4种具有抑制黑色素生物合成活性的单峰物质 ,并将其对B16鼠黑素瘤细胞中黑色素合成的抑制效果进行了评价 ,确定了抑制效果最好的单峰物质MBI -3 # ,其对于B16鼠黑素瘤细胞中黑色素合成的抑制活性为 15 μg/mL ,细胞毒性与最小抑制浓度的比值为 16 67。     

不同聚合度甘露聚糖对甘露聚糖酶生物合成影响的研究

为了研究不同聚合度甘露聚糖对甘露聚糖酶生物合成的影响,进行了不同碳源对甘露聚糖酶生物合成的影响、魔芋甘露聚糖对菌株生长和产酶的影响、不同聚合度的甘露聚糖对甘露聚糖酶的诱导和以低聚合度的甘露聚糖为诱导物生产甘露聚糖酶的研究。结果显示：一株产甘露聚糖酶的菌种产酶存在着代谢终产物阻遏效应,合适的产酶魔芋粉浓度为12g／L,聚合度较小的甘露聚糖诱导的产酶量较大,在发酵培养基中添加低聚合度的魔芋水解物对甘露聚糖酶的生物合成有较大的促进作用,发酵34h酶活可达1831U／mL。     

Wx基因对小麦淀粉合成关键酶活性的影响

为研究Wx基因的缺失对小麦淀粉合成关键酶活性的影响,本试验以8个Wx小麦近等基因系为材料,在灌浆期的10、20、30和40 d取籽粒对ADP-葡萄糖焦磷酸化酶(AGPase)、可溶性淀粉合成酶(SSS)、颗粒结合型淀粉合成酶(GBSS)和淀粉分支酶(SBE)活性进行了测定。结果表明:野生型的AGPase、SSS、GBSS和SBE活性在花后所有时期均最高(GBSS花后40 d除外,处于中间水平),而WxABD型4种淀粉合成相关酶活性几乎在整个灌浆期均低于其余基因型,尤其是WxABD型的GBSS活性尽管也呈现先升高后降低、20 d左右达到高峰的趋势,但其升高或降低的幅度很小,其活性相对较为稳定。研究证明小麦Wx基因缺失对淀粉合成关键酶活性影响较大,依次为Wx-D1Wx-A1WxB1;淀粉合成关键酶活性在花后逐渐增加,以花后20 d最大,此后逐渐降低,到40 d达最低值;WxABD型缺失所有Wx基因,淀粉合成酶活性在花后各时期最低,其中GBSS活性远低于其余基因型且在花后各时期变化较小。     

γ-聚谷氨酸的合成、性质和应用

γ-聚谷氨酸是一种生物可降解的高分子聚合物,可由微生物发酵得到。γ-聚谷氨酸具有良好的水溶性和吸附性,能彻底被生物降解,对环境和人体无害,这使得γ-聚谷氨酸在食品、化妆品、医药和农业等领域具有广阔的应用前景。综述了γ-聚谷氨酸的化学结构、性质、生产方法及其应用。     

L-肉碱的生物学制备及相关研究

L-肉碱是存在于动物组织、植物和微生物中的一种类似维生素的营养物质,在临床、保健等行业有着广泛的应用。本文从理化性质、功能、应用和制备的角度,综述了L-肉碱的相关研究进展,为其大规模的制备提供了理论参考。     

Lipoxygenase activity in olive (Olea europaea) fruit

The present work was designed to characterize lipoxygenase activity in olive fruit pulp, in order to determine its significance in the biosynthesis of virgin olive oil aroma. Lipoxygenase activity has been detected in particulate fractions of enzyme extracts from olive pulp subjected to differential centrifugation. The activity in different membrane fractions showed similar properties, with optimal pH in the range of 5.0–5.5 and a clear specificity for linolenic acid, which was oxidized at a rate double that of linoleic acid under the same reaction conditions. The enzyme preparations displayed very low activity with dilinoleoyl phosphatidylcholine, suggesting that olive lipoxygenase acts on nonesterified fatty acids. The enzyme showed regiospecificity for the Δ-13-position of both linoleic and linolenic acid, yielding 75–90% of Δ-13-fatty acid hydroperoxides. Olives showed the highest lipoxygenase activity about 15 wk after anthesis, with a steady decrease during the developmental and ripening periods. Olive lipoxygenase displayed properties that support its involvement in the biogenesis of six-carbon volatile aldehydes, which are major constituents of the aroma of virgin olive oil, during the process of oil extraction.     

What makes starch from potato (Solanum tuberosum L.) tubers unique: A review

The use of starch in food systems in many instances relies on its thickening and gelling capacity. When native starches fail to match process and/or product‐specific requirements, starches are physically and/or chemically modified to meet end‐use demands. Evidently, differences between starches of varying botanical origin have to be considered when selecting or modifying starches for particular applications. Potato starch (PS) ranks third in world production after maize and wheat starches. Its unique properties differ from those of cereal and pulse starches and are directly related to its molecular structure and organization. This review summarizes the differences between PS and cereal and pulse starches and how they set it apart in terms of gelatinization, pasting, gelation, and retrogradation. Recent advances in improving PS pasting and gelation using enzyme technology and mineral ions are also described.     

聚肽类组织工程材料研究进展

从生物合成聚肽、自组装聚肽和肽／非肽聚合物3个方面,综述了与组织工程相关的聚肽研究的最新进展,并展望了此类材料的优势及发展方向。