【作者】 李丽娜；

【导师】 吴玉清； Rene Buchet；

【作者基本信息】 吉林大学 ， 物理化学， 2008， 博士

【摘要】 本论文由不同的研究课题组成,首先是分子识别,特别是手性分子与蛋白质大分子(BSA)的特异性相互作用的研究。然后是论文的主体部分,分子识别研究被应用并扩展至探寻不同方面的可以选择性作用于生物矿化相关酶(碱性磷酸酶等)的特效抑制剂分子。更准确地讲,是寻找能够通过不同途径和功能抑制病态矿化的抑制剂。主要工作包括以下四个方面:(1)分子识别:由于丹酰基团对环境的高灵敏度和在疏水条件下的较强的荧光响应,我们合成了丹酰-D-苯丙氨酸,丹酰-D-色氨酸,丹酰-D-丝氨酸(其中L型异构体为商品化化合物),并利用荧光光谱法研究了牛血清白蛋白(BSA)对手性氨基酸衍生物的特效识别过程。(2)碱性磷酸酶抑制剂的筛选:我们将用于分子识别研究的丹酰氨基酸衍生物以及130多种苯并噻吩系列物——包括苯并噻吩-四咪唑的衍生物,都应用到碱性磷酸酶的研究体系,研究了化合物对猪肾中提取的组织非特异性碱性磷酸酶(TNAP)和牛肠碱性磷酸酶(BIAP)活性的抑制效应。(3)诱导矿化新模型的构建和矿物形成抑制剂的筛选:一个抑制矿化的有效方法就是寻找类似焦磷酸盐这种能够直接抑制羟磷灰石形成的抑制剂分子。我们构建了一个简单生物的模型在37°C和pH 7.6的条件下模拟矿化过程。这个新模型可以类似基质囊泡在生理条件下诱导HA的生成,从而应用于矿物形成抑制剂的筛选。同时,由于模型中没有任何酶和细胞的干扰,有利于监测HA的成核过程以及其抑制机理的进一步揭示。(4)将抗关节炎特效中药应用于碱性磷酸酶活性检测和基质囊泡诱导的矿化过程的研究:我们将从小鸡胚胎的骺软骨中提取的基质囊泡为模型,利用浑浊度进行原位检测,比较性研究了一系列中药和碱性磷酸酶可溶性抑制剂对碱性磷酸酶活性和矿化过程的不同影响。实验中,通过引入不同底物及改变底物浓度,揭示了这些分子对矿化过程的抑制机理。更多还原

【Abstract】 Although specific recognition of biologically important substrates by enzymes and other biological macromolecules is well known, the detailed molecular mechanisms involved in these specific interactions are only partially elucidated. My Ph D thesis is focused on distinct topics starting from molecular recognition, especially on chiral molecules interacting specifically with proteins such as bovine serum abumin (BSA). Such property was also observed in the case of alkaline phosphatase, which could have medical applications. One application of the ligand recognition by enzymes is the search for their new inhibitors. Tissue non-specific alkaline phosphatase (TNAP), a marker in mineral formation, is enriched in matrix vesicles (MVs) implicated in the initiation of mineral formation. Molecular recognition was exploited by searching inhibitors that can interact selectively with enzymes implicated in the mineralization process. More precisely, our aim was to find inhibitors which can inhibit pathological mineralization by acting in different ways, for example, by altering the enzyme TNAP activity, or by inhibiting HA formation, or by suppressing the calcium and phosphate fluxes. Such specific inhibitors could serve as therapeutical options for curing osteoarthritis.Firstly, during the molecular recognition research, dansyl-D-phenylalanine, dansyl- D-tryptophan, and dansyl-D-serine were successful synthesized (because L-isomers are commercially available). The specific recognition of three amino acid derivatives by BSA indicated that BSA could interact selectively with stereoisomers. The enantioselective ratios (KL/KD) were determined by fluorescence titration spectrum. The findings confirmed that the complex binding was controlled by both the size and the aromaticity of side groups in the process of chiral recognition.Further more, the amino acids derivetives for investigating the molecular recognition as well as a library of over 130 benzothiophenes were screened for their inhibition effects on alkaline phosphatase. Amone them, dansyl-L-phenylalanine was found to be an inhibitor which can selectively interacte with calf intestinal AP. We found also that benzothiophene derivative tetramisoles are water soluble specific inhibitors of TNAP. Both of them were determined as uncompetitive inhibitors.To search inhibitors such as PPi which can directly inhibit HA formation, and to elucidate the inhibition mechanism of mineralization, a simple biological model which can produce HA as MVs was developed by addition of DMSO (4% v/v) in synthetic cartilage lymph (SCL) medium containing calcium and inorganic phosphate at pH 7.6 and 37°C. Inhibitors of HA formation were screened, providing the evidence that several nucleotides are inhibitors of HA formation and the inhibition mechanism was elucidated.In addition, MVs which initiate calcification in osseous tissues undergoing both physiological and pathological calcifications served to determine the effects of Chinese drugs on TNAP activity and mineralization process. We demonstrated that the anti-rheumatic Chinese medicine sinomenine having no effect on TNAP, sinomenine and theophylline (a TNAP inhibitor), both slowed down the HA formation by interfering probably with Pi or Ca2+ transports. It was concluded that Sinomenine, by delaying HA formation could indirectly boost its anti-inflammatory effect. Although the mineralization models do not address cellular issues, they presented great potential to screen putative drugs to cure osteoarthritis.更多还原