STRUCTURAL STUDIES OF ICE NUCLEATOR PROTEINS USING SMALL-ANGLE X-RAY SCATTERING

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 冷冻是保存食品最好的方法之一。在食品冷冻过程中，化学降解和微生物腐烂的速度很低，导致营养物质得到保存，保质期延长。当样品在凝固前降至冰点以下时，就会发生过冷。冰核是一个初始冰晶形成并开始生长的过程。过冷度和成核率直接影响着冰的生长模式和能源成本。以前的研究已经证明了冰核活性细菌(INA)、紫丁香菌和欧文氏杆菌对一些模型和真实食品系统的冷冻具有潜在的节能和提高质量的效果(Huang等，2001)。他们还成功地分离、纯化和鉴定了从根癌埃希氏菌中分离、纯化和鉴定的胞外冰核因子(Li和Lee，1998a)。生物冰核的使用是生物技术的一个独特应用，因为它直接改进了冷冻过程。然而，到目前为止，大多数研究都集中在冰核蛋白的生物学效应及其应用上。目前还没有人研究了解这些独特的冰核蛋白的结构。因此，本BEAM循环的主要目的是了解细胞外冰核蛋白的构象随pH、离子强度、蛋白质浓度和温度等物理化学参数的变化。将建立ECINs的结构和成冰活性之间的关联。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Freezing is one of the best methods for food preservation. During the process of food freezing, chemical degradation and microbial spoilage occur at a very low rate, resulting in preserved nutrients and prolonged shelf life. Supercooling occurs when sample temperatures drop below their freezing points prior to solidification. Ice nucleation is a process where initial ice crystals are formed and begin to grow. Supercooling and ice nucleation rates directly affect ice growth pattern and energy costs. Previous researches have demonstrated the effect of potential energy saving and quality improvement of Ice-Nucleation Active (INA) bacteria, P. syringae and Erwinnia herbicola on the freezing of some model and real food systems (Huang et al., 2001). They also succeeded in isolation, purification and characterization of the extracellular ice nucleators (ECINs) from E. herbicola (Li and Lee, 1998a). The use of a biogenic ice nucleator is a unique application of biotechnology, as it directly improves freezing processes. However, until now, most of the researches have been focused on biological effects of ice nucleator proteins as well as their applications. No research has been done to understand the structure of these unique ice nucleator proteins. Therefore, the main objective of this beam- cycle is to understand the conformation change of extracellular ice nucleator proteins with physicochemical parameters, such as pH, ionic strength, protein concentration, and temperature. The correlation between structure and ice nucleating activities of ECINs will be established.