No abstract available.
Binding Sites* ; Gonadotropins* ; Humans* ; Ovarian Neoplasms*

No abstract available.
Animals ; Binding Sites* ; Carbon Monoxide* ; Carbon* ; Rats* ; Serotonin*

The action of chlorpromazine on Na-K-ATPase activity of rabbit brain homogenate was examined. The results were summarized as the follows: 1. Chlorpromazine inhibited Na-K-ATPase activity in the a dose dependent manner with an estimated I50 of 6s 10(-5)M. 2. Hydrolysis of ATP was linear with time and enzyme concentration with or without cholorpromazine in reaction mixture. 3. Altered pH and activity curves of Na-K-ATPase demonstrated comparable inhibition by chlorpromazine in fuffered acidic, netral and alkaline pH ranges. 4. Kinetic analysis of the effect of chlorpromazine on the various parameters which influence Na-K-ATPase activity revealed that the inhibition was apparently competitive with respect to Na+, and noncompetitive with repect to ATP and K+. Based on these data it is suggested that the inhibition by chlorpromazine is not a consequence of change of affinities of ATP, Mg++ and K+ for the enzyme. Results also indicate that chlorpromazine at the Na+ binding site has an important functional role for the activation of the enzymeby Na+.
Adenosine Triphosphate ; Binding Sites ; Brain* ; Chlorpromazine* ; Hydrogen-Ion Concentration ; Hydrolysis

Binding Sites ; Hepatitis B virus ; physiology ; Virus Attachment

Antibody drug conjugates (ADCs) are an emerging class of targeted therapeutics with the potential to improve therapeutic index over the traditional chemotherapy. However, it is difficult to control the site and stoichiometry of conjugation in mAb, typically resulting in heterogeneous mixtures of ADCs that are difficult to optimize. New methods for site-specific drug attachment allow development of more homogeneous conjugates and control of the site of drug attachment. In this article, the new literature on development of ADCs and site-specific ADCs is reviewed. In addition, we summarized the various strategies in production of site-specific ADCs.
Antibodies, Monoclonal ; chemistry ; Antibody Specificity ; Binding Sites, Antibody ; Immunoconjugates ; chemistry

To understand the mechanism of transcriptional regulation, it is essential to detect promoters and regulatory elements. Various kinds of methods have been introduced to improve the prediction accuracy of regulatory elements. Since there are few experimentally validated regulatory elements, previous studies have used criteria based solely on the level of scores over background sequences. However, selecting the detection criteria for different prediction methods is not feasible. Here, we studied the calibration of thresholds to improve regulatory element prediction. We predicted a regulatory element using MATCH, which is a powerful tool for transcription factor binding site (TFBS) detection. To increase the prediction accuracy, we used a regulatory potential (RP) score measuring the similarity of patterns in alignments to those in known regulatory regions. Next, we calibrated the thresholds to find relevant scores, increasing the true positives while decreasing possible false positives. By applying various thresholds, we compared predicted regulatory elements with validated regulatory elements from the Open Regulatory Annotation (ORegAnno) database. The predicted regulators by the selected threshold were validated through enrichment analysis of muscle-specific gene sets from the Tissue-Specific Transcripts and Genes (T-STAG) database. We found 14 known muscle-specific regulators with a less than a 5% false discovery rate (FDR) in a single TFBS analysis, as well as known transcription factor combinations in our combinatorial TFBS analysis.
Binding Sites* ; Calibration ; Regulatory Sequences, Nucleic Acid ; Transcription Factors*

The mammalian amygdala comprises a heterogeneous complex of cytoarchitectonically, histochemically and connectionally distinct nuclei. To investigate the developmental changes and regional distributions of adrenoceptor binding sites in the adult and postnatal rat amygdala (postnatal days 0, 5, 10, 15, 20, 30), in vitro autoradiography was performed. Binding sites for the alpha1-adrenoceptor ligand [3H]-prazosin, the alpha2-adrenoceptor ligand [3H]-rauwolscine, and the beta-adrenoceptor ligand [125I]-iodocyanopindolol were visualized by the in vitro autoradiography, and anatomically localized by comparing the autoradiograms to Nissl- and acetylcholinesterase-stained sections. On toluidine blue- and acetylcholinesterase-stained sections of the amygdaloid complex of the rat, three major divisions can be distinguished: the cortical-like nuclear group, medial nuclear group, and central nuclear group. The basolateral nuclear group of the cortical-like nuclear group was divided into three subregions, the basal, the basolateral and the basomedial amygdaloid nucleus. Between the medial and the basolateral amygdaloid nucleus, the intercalated nuclei were observed. The highest number of alpha1-adrenoceptor binding sites was detected in the central and the lateral amygdaloid nucleus. The nuclei most strongly labeled by [3H]-rauwolscine were those in the medial part of the amygdaloid complex. The pattern of the beta-adrenoceptor binding was relatively diffuse, the medial amygdaloid nucleus was most strongly labeled among the amygdaloid nuclei. At the postnatal day 0, adrenergic receptor binding sites were only weakly labeled. The expression of a1-adrenoceptor binding was rapidly increased in the central amygdaloid nucleus at the postnatal day 5, and between the postnatal day 10 and 15, the concentration of bindig sites reached the adult levels. The expression of alpha2- and beta-adrenoceptor binding was increased in most amygdaloid nuclei at the postnatal day 10, and higher density was observed at the postnatal day 30. In the adult, the expression of adrenoceptor binding was relatively low in most nuclei when compared to postnatal day 30. These findings may provide evidence that alpha1-adrenoceptor is involved in regulating amygdaloid development and function more specifically than alpha2- and beta-adrenoceptor during postnatal development. These results indicate that the regional distributions of alpha1-, alpha2-, and beta-adrenoceptor show some differences from those of the other mammalian species reported.
Adult ; Amygdala* ; Animals ; Autoradiography ; Binding Sites ; Humans ; Rats* ; Receptors, Adrenergic*

Diacylglycerol (DAG) is an intermediate product in lipid metabolism and plays an important physiological role in human body. It is mainly prepared by hydrolyzing lipid with lipase. However, research on the detection method of 1, 2-diacylglycerol (1, 2-DAG) and 1, 3-diacylglycerol (1, 3-DAG) and catalytic specificity of lipase was not enough, which limits its wide application. To address these challenges, an efficient quantitative detection method was first established for 1, 2-DAG (0.025-0.200 g/L) and 1, 3-DAG (0.025-0.150 g/L) by combining supercritical fluid chromatography with evaporative light scattering detector and optimizing the detection and analysis parameters. Based on the molecular docking between Thermomyces lanuginosus lipase (TLL) and triolein, five potential substrate binding sites were selected for site-specific saturation mutation to construct a mutation library for enzyme activity and position specificity screening. The specificity of sn-1, 3 of the I202V mutant was the highest in the library, which was 11.7% higher than the specificity of the wild type TLL. In summary, the position specificity of TLL was modified based on a semi-rational design, and an efficient separation and detection method of DAG isomers was also established, which provided a reference for the study of the catalytic specificity of lipase.
Humans ; Diglycerides ; Molecular Docking Simulation ; Binding Sites ; Catalysis ; Lipase/genetics*

OBJECTIVE: This study is to explore the effects on specific bindings between [ 3H]RX821002, alpha-2 adrenergic receptor antagonist and alpha-2 adrenergic receptor in rat brain by G-protein modulation. METHODS: The radioligand binding receptor study was conducted with [ 3H]RX821002, a new alpha-2 adrenergic receptor antagonist, in the presence or absence of Gpp(NH)p and pertussis toxin. RESULTS: The alpha-2 adrenergic receptors were saturated with [ 3H]RX821002 in the fashion of the single binding site. The dissociation constant (Kd) was 0.70+/-0.30 nM, and maximum binding (Bmax) was 599.9+/-283.4 fmol/mg protein. The saturation study showed that the maximum binding (B max ; 668.0+/-50.1 fmol/mg protein) was increased and the dissociation constant (Kd ; 0.61+/-0.14 nM) was decreased significantly in the presence of Gpp (NH)p compared to those (B max ; 559.8+/-81.9 fmol/mg protein, Kd ; 0.87+/-0.14 nM) in the absence of Gpp (NH)p (by paired t-test ; B max, p=0.023, Kd, p=0.005). In the presence of pertussis toxin, the maximum binding (B max ; 617.0+/-58.5 fmol/mg protein) was increased significantly (by paired t-test ; B max, p=0.001) but the issociation constant (Kd ; 0.92+/-0.24 nM) was not decreased compared to those (B max ; 554.1+/-66.1 fmol/mg protein, Kd ; 0.89+/-0.24 nM) in the absence of pertussis toxin. CONCLUSION: These results confirm that the binding profiles between [ 3H]RX821002 and alpha-2 adrenergic receptors be modified by G-protein modulation. This suggests that the drug effects on receptors be influenced by various conditions such as G-protein modulation.
Animals ; Binding Sites ; Brain* ; GTP-Binding Proteins* ; Guanylyl Imidodiphosphate ; Pertussis Toxin ; Rats* ; Receptors, Adrenergic, alpha-2

OBJECTIVETo investigate the binding characteristics between an artificial Arg-Gly-Asp (RGD)-containing cyclic peptide [cyclo(CGRGDSPK)] and rat hepatic stellate cells (HSC).

METHODSAn artificial RGD-containing cyclic peptide was labeled with fluorescein isothiocyanate (FITC). HSCs were isolated by collagenase in situ liver recirculating and purified by density gradient centrifugation from normal rats. The cells were cultured for 5 days of primary culture (quiescent phenotype) or for 7 days of secondary culture (activated phenotype). To access the binding and uptake, HSCs were incubated with FITC-cRGD of different concentrations at 4 degree C or 37 degree C, and then the binding and uptake were investigated by flow cytometry. The location of FITC-cRGD in HSC was investigated by fluorescent microscopy. Kd and maximal binding sites per cell were calculated by radioligand binding assay (RBA) of receptors using 3H-cRGD. In the interim, FITC-cAGA was used as a peptide control devoid of any binding site.

RESULTSThe binding between FITC-cRGD and HSC was saturable, time- and dose-dependent and could compete with overdosed unlabeled cRGD. The fluorescence was mainly distributed in cytoplasma, especially near the nuclei. Kd was 7.05 x 10(-9) mol/L and Bmax per cell was nearly 6.79 x 10(5).

CONCLUSIONSThe results demonstrate that cRGD are specifically taken up by HSC through a receptor-mediated pathway. The information is useful for understanding the ligand-receptor interaction of HSC. FITC labeled cyclic RGD-peptides meet the standards of special ligands and FITC does not change the binding activation of cyclic RGD-peptides.

Animals ; Binding Sites ; Cells, Cultured ; Hepatocytes ; cytology ; metabolism ; Oligopeptides ; pharmacology ; Peptides, Cyclic ; pharmacology ; Protein Binding ; Rats