Non-complexed Forms Research Articles

P.671 Efficacy and safety of lumateperone tosylate 42mg in the treatment of schizophrenia: A pooled analysis of phase 2 and 3 studies

Transient absorption spectroscopy in combination with in silico methods has been employed to study the interactions between human serum albumin (HSA) and the anti-psychotic agent chlorpromazine (CPZ) as well as its two demethylated metabolites (MCPZ and DCPZ). Thus, solutions containing CPZ, MCPZ or DCPZ and HSA (molar ligand:protein ratios between 1:0 and 1:3) were submitted to laser flash photolysis and the ΔAmax value at λ = 470 nm, corresponding to the triplet excited state, was monitored. In all cases, the protein-bound ligand exhibited higher ΔAmax values measured after the laser pulse and were also considerably longer-lived than the non-complexed forms. This is in agreement with an enhanced hydrophilicity of the metabolites, due to the replacement of methyl groups with H that led to a lower extent of protein binding. For the three compounds, laser flash photolysis displacement experiments using warfarin or ibuprofen indicated Sudlow site I as the main binding site. Docking and molecular dynamics simulation studies revealed that the binding mode of the two demethylated ligands with HSA would be remarkable different from CPZ, specially for DCPZ, which appears to come from the different ability of their terminal ammonium groups to stablish hydrogen bonding interactions with the negatively charged residues within the protein pocket (Glu153, Glu292) as well as to allocate the methyl groups in an apolar environment. DCPZ would be rotated 180° in relation to CPZ locating the aromatic ring away from the Sudlow site I of HSA.

Investigation of metabolite-protein interactions by transient absorption spectroscopy and in silico methods.

Transient absorption spectroscopy in combination with in silico methods has been employed to study the interactions between human serum albumin (HSA) and the anti-psychotic agent chlorpromazine (CPZ) as well as its two demethylated metabolites (MCPZ and DCPZ). Thus, solutions containing CPZ, MCPZ or DCPZ and HSA (molar ligand:protein ratios between 1:0 and 1:3) were submitted to laser flash photolysis and the ΔAmax value at λ = 470 nm, corresponding to the triplet excited state, was monitored. In all cases, the protein-bound ligand exhibited higher ΔAmax values measured after the laser pulse and were also considerably longer-lived than the non-complexed forms. This is in agreement with an enhanced hydrophilicity of the metabolites, due to the replacement of methyl groups with H that led to a lower extent of protein binding. For the three compounds, laser flash photolysis displacement experiments using warfarin or ibuprofen indicated Sudlow site I as the main binding site. Docking and molecular dynamics simulation studies revealed that the binding mode of the two demethylated ligands with HSA would be remarkable different from CPZ, specially for DCPZ, which appears to come from the different ability of their terminal ammonium groups to stablish hydrogen bonding interactions with the negatively charged residues within the protein pocket (Glu153, Glu292) as well as to allocate the methyl groups in an apolar environment. DCPZ would be rotated 180° in relation to CPZ locating the aromatic ring away from the Sudlow site I of HSA.

Synthesis, characterization and palladium complex formation of pyridinium- and quinolinium-3-acetylides: mesomeric betaines or betaine-stabilized carbenes?

3-Ethynyl-1-methylpyridinium- and 3-ethynyl-1-methyl-quinolinium triflates were prepared by methylation of 3-ethynylpyridine and 3-ethynylquinoline with methyl triflate, respectively. Whereas deprotonation of the former mentioned salt gave no stable product, sodium hydroxide in methanol formed 1-methylquinolinium-3-acetylide which could be characterized NMR spectroscopically. Considerable upfield shifts of the resonance frequencies in combination with DFT calculations of bond lengths reveal that the structure has to be represented by resonance forms of a quinolinium-3-acetylide, i.e., as mesomeric betaine, as well as by allenylidene resonance forms. The Pd complex of this species was prepared by reaction of 3-ethynylquinoline with Pd(PPh3)2Cl2 in the presence of CuI and diethylamine to give bis(triphenylphosphine)bis(quinolin-3-yl-ethynyl)palladium(II) which was subsequently methylated at the nitrogen atoms. Insertion reactions of 3-(bromoethynyl)pyridine with Pd(PPh3)4 gave bis(triphenylphosphine)palladium(II)(pyridin-3-yl-ethynyl) bromide which was finally methylated to give bis(triphenylphosphine)[(1-methylpyridinium-3-yl)ethynyl]palladium(II)bromide triflate. Likewise, bis(triphenylphosphine)palladium(II) (quinolin-3-yl-ethynyl) bromide and bis(triphenylphosphine)((1-methylquinolinium-3-yl)ethynyl)palladium(II)bromide triflate were prepared. In contrast to the non-complexed forms, the spectroscopic data are in accordance with alkynyl palladium complexes rather than with allenylidene complexes.

Multi-center analytical performance evaluation of the Access Hybritech® p2PSA immunoassay

BackgroundTotal PSA assays measure both complexed and non-complexed forms of PSA while free PSA assays only measure non-complexed forms. Free PSA is a mixture of isoforms including immature PSA (proPSA) with retained portions of the leader sequence (e.g. [−7], [−4], and [−2]proPSA) and nicked forms (BPSA). ProPSA isoforms in male sera have been associated with prostate cancer. This study characterized the analytical performance of a chemiluminescent immunoassay for [−2]proPSA. MethodsThe Access Hybritech p2PSA assay is a sandwich immunoassay using an anti-[−2]proPSA monoclonal antibody attached to paramagnetic beads and an anti-PSA monoclonal antibody conjugated to alkaline phosphatase calibrated with recombinant [−2]proPSA. Analytical studies including sensitivity (CLSI EP17-A) and imprecision (CLSI EP5-A2) were performed. ResultsThe Access Hybritech p2PSA assay for [−2]proPSA had a dynamic range of 0.5 to 5000pg/ml. The total CV of the assay was <7% for [−2]proPSA concentrations between 20 and 1000pg/ml. The LOB was 0.50pg/ml, LOD 0.69pg/ml, and LOQ 3.23pg/ml (20% CV). There was no hook effect up to 15,000pg/ml. There was a <5% difference between calibrator and reagent lots and no interference from normal serum constituents. ConclusionsThe Access Hybritech p2PSA assay is a robust immunoassay for the measurement of serum [−2]proPSA.

EFFECT OF HEMODILUTION ON PROSTATIC SPECIFIC ANTIGEN IN OBESE MEN

Total PSA assays measure both complexed and non-complexed forms of PSA while free PSA assays only measure non-complexed forms. Free PSA is a mixture of isoforms including immature PSA (proPSA) with retained portions of the leader sequence (e.g. [− 7], [− 4], and [− 2]proPSA) and nicked forms (BPSA). ProPSA isoforms in male sera have been associated with prostate cancer. This study characterized the analytical performance of a chemiluminescent immunoassay for [− 2]proPSA.The Access Hybritech p2PSA assay is a sandwich immunoassay using an anti-[− 2]proPSA monoclonal antibody attached to paramagnetic beads and an anti-PSA monoclonal antibody conjugated to alkaline phosphatase calibrated with recombinant [− 2]proPSA. Analytical studies including sensitivity (CLSI EP17-A) and imprecision (CLSI EP5-A2) were performed.The Access Hybritech p2PSA assay for [− 2]proPSA had a dynamic range of 0.5 to 5000 pg/ml. The total CV of the assay was < 7% for [− 2]proPSA concentrations between 20 and 1000 pg/ml. The LOB was 0.50 pg/ml, LOD 0.69 pg/ml, and LOQ 3.23 pg/ml (20% CV). There was no hook effect up to 15,000 pg/ml. There was a < 5% difference between calibrator and reagent lots and no interference from normal serum constituents.The Access Hybritech p2PSA assay is a robust immunoassay for the measurement of serum [− 2]proPSA.

Calpain-1-dependent degradation of troponin I mutants found in familial hypertrophic cardiomyopathy.

The mechanism by which mutations of the cardiac troponin I (cTnI) gene evoke familial hypertrophic cardiomyopathy (fHCM) is unknown. In this investigation the potential effects of three fHCM-related cTnI mutations on Calpain-1-induced cTnI degradation were tested, and a study was made of whether additional conformational changes due to troponin complex formation and protein kinase A-induced phosphorylation affect the intensity of cTnI proteolysis. Purified recombinant wild-type cTnI and three of its fHCM-related missense mutants (R145G, G203S and K206Q), alone or in the troponin complex (i.e. together with troponin C and troponin T), in the non-phosphorylated or protein kinase A-bisphosphorylated forms were proteolyzed in vitro in the presence of Calpain-1 (0.05-2.5 U) at 30 degrees C. Following incubation with Calpain-1 for 0.5, 30, 60 or 120 min, the extent of protein degradation was evaluated through the use of Western immunoblotting and densitometry. The results indicated that both the wild-type and the mutant cTnI molecules were susceptible to Calpain-1. However, the degradation of the cTnI molecules in the troponin complex was less intense than that of the non-complexed forms. Moreover, phosphorylation by protein kinase A conferred effective protection against cTnI proteolysis. The data suggested that mutations in the central inhibitory domain (R145G) and in the C-terminal region (G203S and K206Q) of cTnI do not affect its Calpain-1-mediated degradation, or the phosphorylation-induced protection against proteolysis.

Regulation of the activity of matriptase on epithelial cell surfaces by a blood-derived factor.

Matriptase is an epithelial-derived, integral membrane, trypsin-like serine protease. We have shown previously that matriptase exists both in complexed and noncomplexed forms. We now show that the complexed matriptase is an activated, two-chain form, which is inhibited in an acid-sensitive, reversible manner through binding to its cognate, Kunitz-type inhibitor, HAI-1 (hepatocyte growth factor activator inhibitor-1). Conversely, the majority of the noncomplexed matriptase is a single-chain zymogen, which lacks binding affinity to HAI-1, suggesting that matriptase, similar to most other serine proteases, is activated by proteolytic cleavage at a canonical activation motif. We have now generated mAbs specific for the conformational changes associated with the proteolytic activation of matriptase. Using these mAbs, which specifically recognize the two-chain form of matriptase, we demonstrate that matriptase is transiently activated on 184A1N4 human mammary epithelial cell surfaces following their exposure to serum. The ability of serum to activate matriptase is highly conserved across reptilian, avian, and mammalian species. This serum-dependent activation of matriptase on epithelial cell surfaces is followed by ectodomain shedding of both matriptase and its Kunitz-type inhibitor.

Studies of the complexation of sugars by diffusion-ordered NMR spectroscopy

In the presence of lanthanide cations, some sugars with a special relationship between their hydroxyl groups are able to form complexes in water. Diffusion-ordered NMR spectroscopy (DOSY) can be used as a tool to distinguish between the complexed and noncomplexed forms in a mixture due to the differences in their relative diffusion coefficient values. The lowest diffusion was attributed to the complexed species because of the increase in both size and molecular weight when compared with the noncomplexed forms. Mixtures of sugars of the same molecular weight and also the isomers of a single monosaccharide can be ‘separated’ by DOSY on the basis of their different tendencies to form complexes with different diffusion coefficient values.

LNCaP produces both putative zymogen and inactive, free form of prostate-specific antigen.

Our objective was to investigate the presence of prostate specific antigen (PSA) and alpha-1-antichymotrypsin (ACT) mRNA and protein in prostate cancer cell lines, and the complexing characteristics of expressed PSA. RT-PCR, immunohistochemistry, and Western blots were employed. Trypsin treatment of PSA was performed to establish the possible presence of an activatable form of PSA. ACT mRNA and protein were detected in LNCaP, PC-3, and DU 145 by RT-PCR and by immunohistochemistry, respectively. Only LNCaP cells were positive for PSA mRNA and protein. LNCaP expressed approximately 30% active PSA, approximately 40% putative zymogen form of PSA, and approximately 30% stably inactive PSA. We have shown that the majority of PSA expressed by LNCaP cells is present in free, noncomplexed forms in the conditioned media. A portion (40%) can be activated by trypsin, while the rest is stably inactive PSA. LNCaP cells may serve as a source of the "unreactive" PSA present in prostate cancer patients' serum.

LNCaP produces both putative zymogen and inactive, free form of prostate‐specific antigen

BACKGROUND Our objective was to investigate the presence of prostate specific antigen (PSA) and α-1-antichymotrypsin (ACT) mRNA and protein in prostate cancer cell lines, and the complexing characteristics of expressed PSA. METHODS RT-PCR, immunohistochemistry, and Western blots were employed. Trypsin treatment of PSA was performed to establish the possible presence of an activatable form of PSA. RESULTS ACT mRNA and protein were detected in LNCaP, PC-3, and DU 145 by RT-PCR and by immunohistochemistry, respectively. Only LNCaP cells were positive for PSA mRNA and protein. LNCaP expressed ∼30% active PSA, ∼40% putative zymogen form of PSA, and ∼30% stably inactive PSA. CONCLUSIONS We have shown that the majority of PSA expressed by LNCaP cells is present in free, noncomplexed forms in the conditioned media. A portion (40%) can be activated by trypsin, while the rest is stably inactive PSA. LNCaP cells may serve as a source of the “unreactive” PSA present in prostate cancer patients' serum. Prostate 35:135–143, 1998. © 1998 Wiley-Liss, Inc.

A Family of Single-Isomer Chiral Resolving Agents for Capillary Electrophoresis. 3. Heptakis(2,3-dimethyl-6-sulfato)-β-cyclodextrin

The third member of a new family of single-isomer charged cyclodextrins, the sodium salt of heptakis(2,3-dimethyl-6-sulfato)-β-cycldextrin, has been synthesized, characterized, and used for the capillary electrophoretic separation of the enantiomers of neutral, acidic, basic, and zwitterionic analytes. Though heptakis(2,3-dimethyl-6-sulfato)-β-cyclodextrin complexes much less strongly with any of the analytes tested here than the previously synthesized heptakis(2,3-diacetyl-6-sulfato)-β-cyclodextrin and heptakis-6-sulfato-β-cyclodextrin, it offers excellent enantioselectivities, complementary to those of the other two single-isomer, differently functionalized charged cyclodextrins. Confirming the predictions of the charged resolving agent migration model, heptakis(2,3-dimethyl-6-sulfato)-β-cyclodextrin allowed for the reversal of the migration order of the enantiomers of neutral analytes as the cyclodextrin concentration was increased. Just as with the previous two single-isomer charged resolving agents, separation selectivity for the acidic, basic, and zwitterionic analytes could increase, decrease, or pass a maximum as the cyclodextrin concentration was increased, depending on the respective binding strength of the enantiomers and the ionic mobilities of both the complexed and noncomplexed forms of the enantiomers.

A Family of Single-Isomer Chiral Resolving Agents for Capillary Electrophoresis. 2. Hepta-6-sulfato-β-cyclodextrin

A new, hydrophilic, single-isomer charged cyclodextrin, the sodium salt of hepta-6-sulfato-β-cyclodextrin has been synthesized, characterized, and used for the capillary electrophoretic separation of the enantiomers of numerous noncharged, acidic, basic, and zwitterionic analytes. Hepta-6-sulfato-β-cyclodextrin proved to be a much stronger complexing agent for all the analytes tested, in both low-pH and high-pH background electrolytes, than the previously synthesized, moderately hydrophobic heptakis(2,3-diacetyl-6-sulfato)-β-cyclodextrin. The separation selectivities of the two single-isomer, differently functionalized charged cyclodextrins often proved to be complementary. In agreement with the predictions of the charged resolving agent migration model, separation selectivity for the noncharged analytes decreased as the concentration of hepta-6-sulfato-β-cyclodextrin was increased. For acidic, basic, and zwitterionic analytes, selectivity could increase, decrease, or pass a maximum, depending on the binding strength of the enantiomers and ionic mobilities of both the complexed and noncomplexed forms of the enantiomers.