35MHz quartz crystal microbalance and surface plasmon resonance studies on the binding of angiotensin converting enzyme with lisinopril

Research on Dual-Technology Fusion Biosensor Chip Based on RNA Virus Medical Detection

In recent years, the emergence of COVID-19 and other epidemics caused by RNA(ribonucleic acid)-type genetic viruses has aroused the close attention of governments around the world on emergency response to public safety and health emergencies. In this paper, an electrodeless biosensing detection chip for RNA virus medical detection is designed using quartz crystal microbalance technology and local surface plasmon resonance technology. The plasmonic resonance characteristic in the nanostructures of gold nanorods-quartz substrates with different parameters and the surface potential distribution of the quartz crystal microbalance sensing chip were studied by COMSOL finite element simulation software. The results show that the arrangement structure and spacing of gold nanorod dimers greatly affect the local surface plasmon resonance of nanorods, which in turn affects the detection results of biomolecules. Moreover, high concentrations of "hot spots" are distributed between both ends and the gap of the gold nanorod dimer, which reflects the strong hybridization of the multiple resonance modes of the nanoparticles. In addition, by simulating and calculating the surface potential distribution of the electrode area and non-electrode area of the biosensor chip, it was found that the biosensor chip with these two areas can enhance the piezoelectric effect of the quartz chip. Under the same simulation conditions, the biochip with a completely electrodeless structure showed a better sensing performance. The sensor chip combining QCM and LSPR can reduce the influence of the metal electrode on the quartz wafer to improve the sensitivity and accuracy of detection. Considering the significant influence of the gold nanorod dimer plasma resonance mode and the significant advantages of the electrodeless biosensor chip, an electrodeless biosensor combining these two technologies is proposed for RNA virus detection and screening, which has potential applications in biomolecular measurement and other related fields.

Synthesis and Crystalline Structure of Zinc Complexes with Antihypertensive Drug Lisinopril

The structural investigation of Zn2+ complexes with the ligand lisinopril (LIS), an inhibitor of angiotensin-converting enzyme (ACE), was performed. The main objective is to compare if Zn-LIS coordination in vitro is similar to that observed in vivo. Two zinc complexes were obtained from different synthetic routes. The synthesis of LISZn1 used stirring, while for LISZn2 involved solvothermal conditions, which favoured the full deprotonation of lisinopril ligand. In this sense, the different synthetic routes resulted in the formation of complexes with notorious chemical and structural differences. The crystal structure of LISZn2 showed that the ligand is coordinated to Zn2+ ion by oxygen and nitrogen atoms which is different from that observed in vivo. In vitro, the coordination of lisinopril occurs only by an oxygen atom of the central carboxylate group. LISZn2 forms a one-dimensional (1D) coordination polymer and presents disorder atoms in its unit cell.

Overview of the detection methods for equilibrium dissociation constant KD of drug-receptor interaction

Drug-receptor interaction plays an important role in a series of biological effects, such as cell proliferation, immune response, tumor metastasis, and drug delivery. Therefore, the research on drug-receptor interaction is growing rapidly. The equilibrium dissociation constant (KD) is the basic parameter to evaluate the binding property of the drug-receptor. Thus, a variety of analytical methods have been established to determine the KD values, including radioligand binding assay, surface plasmon resonance method, fluorescence energy resonance transfer method, affinity chromatography, and isothermal titration calorimetry. With the invention and innovation of new technology and analysis method, there is a deep exploration and comprehension about drug-receptor interaction. This review discusses the different methods of determining the KD values, and analyzes the applicability and the characteristic of each analytical method. Conclusively, the aim is to provide the guidance for researchers to utilize the most appropriate analytical tool to determine the KD values.

Surface plasmon resonance analysis of the binding mechanism of pharmacological and peptidic inhibitors to human somatic angiotensin I-converting enzyme

Somatic angiotensin I-converting enzyme (ACE) possesses two catalytic domains and plays a major role in the regulation of blood pressure, thus representing a therapeutic target for the treatment of hypertension. We present a comprehensive surface plasmon resonance (SPR) study of the interaction of human somatic ACE with the pharmacological inhibitors captopril and lisinopril, the bradykinin potentiating peptide BPP-11b, and the food peptidic inhibitors from bovine αs2-casein, F(174)ALPQYLK(181) and F(174)ALPQY(179). SPR binding curves recorded with the high potency inhibitors captopril, lisinopril, and BPP-11b were evaluated both by regression analysis and by kinetic distribution analysis. The results indicated that captopril and lisinopril bound ACE with two K(D)'s differing by a factor 10-20 and >30, respectively (lowest K(D) = 0.1-0.3 nM for both inhibitors). This shows, for the first time in a direct binding assay with the two-domain enzyme, the existence of two binding modes of the pharmacological inhibitors, presumably with the two ACE domains. The BPP-11b-ACE binding curves were complex but showed a predominant interaction with K(D) in the nanomolar range. The caseinopeptides, known to inhibit ACE with an IC₅₀ of 4.3 μM, bound to ACE with K(D) = 3-4 μM. Mapping of the F(174)ALPQY(179) binding site on ACE by sequential binding studies using captopril or BPP-11b indicated that it bound to (or near) the two active sites of ACE, in agreement with the stoichiometry of 2 determined from data fitting. Our results provide a detailed characterization of ACE-inhibitor binding modes and validate SPR for predicting the inhibitory potential of new compounds.