Analysis of binding conformations of drugs to human serum albumin (site I and site II) by NMR measurements and computational calculations

(1)用CAMDAS、SUPERPOSE和TRNOE实验研究了药物与HAS位点I和位点II的结合构象。我们结合了从CAMDAS和TRNOE获得的距离信息，以提取与HAS结合的药物的“结合构象异构体”（位点I和位点II）。(2)位点I结合药物对于BMT，获得了一种选择的构象异构体（BMT 354）。以BMT 354的基本结合构象结构为“模板”，选择FUCI和IM的结合构象。因此，我们可以有效地选择一个结合构象的FUCI和IM。(3)位点II结合药物对于托美丁（TLM），CAMDAS生成的构象异构体中只有一种（TLM 53）满足NOESY获得的距离限制条件。以TLM（conf 53）的结构为“模板”，通过分子叠加选择与其他药物结合的构象。我们可以有效地选择ETH-A，R-IB，S-IB，R-KP和S-KP的一种结合构象。(4)然后，我们构建了药物的复杂结构，（BMT 354，TLM 53）和HAS的晶体结构，使用SYBYL（Tripos）中实现的Flexi Dock程序。该方法结合MD计算，SUPERPOSE和TRNOE测量是获得药物与HAS结合的空间构象的一种非常有效的方法。药物在结合部位的结合构象（位点I和位点II）用于探测药物-HAS互补相互作用。

(1) The binding conformations of drugs to site I and site II of HAS has been investigated by CAMDAS, SUPERPOSE and TRNOE experiments. We have combined distance information obtained from CAMDAS and TRNOE to perform an extraction of a "binding conformer" for drugs binding to the HAS (site I and site II ).(2) Site I binding drugsFor BMT, one selected conformer (BMT354) was obtained. The basic binding conformer structure of BMT354 was taken as a "template" to choose binding conformers for FUCI and IM. Consequently, we could efficiently select one binding conformer for FUCI and IM.(3) Site II binding drugsFor tolmetin (TLM), only one conformer (TLM 53) among conformers generated by CAMDAS satisfied the distance restraint conditions obtained from NOESY. The structure of the TLM (conf53) was taken as a "template" to choose binding conformers for other drugs by molecular overlay. We could efficiently select one binding conformer for ETH-A, R-IB, S-IB, R-KP and S-KP.(4) Then, we constructed the complex structure of drugs (BMT354, TLM53) and HAS based on the crystal structure of HAS using Flexi Dock program implemented in SYBYL (Tripos).This method of combining MD calculation, SUPERPOSE and TRNOE measurements suggested to an extremely effective method for obtaining steric conformation for drugs bound to HAS.Binding conformer of the drugs in the binding site (site I and site II ) of HAS was used to probe the drug-HAS complementary interactions.