Brain mural cell loss in the parietal cortex in Alzheimer's disease correlates with cognitive decline and TDP-43 pathology.

AIMS: Brain mural cells (BMC), smooth muscle cells and pericytes, interact closely with endothelial cells and modulate numerous cerebrovascular functions. A loss of BMC function is suspected to play a role in the pathophysiology of Alzheimer's Disease (AD). METHODS: BMC markers, namely smooth muscle alpha actin (α-SMA) for smooth muscle cells, as well as platelet-derived growth factor receptor ß (PDGFRß) and aminopeptidase N (ANPEP or CD13) for pericytes, were assessed by Western immunoblotting in microvessel extracts from the parietal cortex of 60 participants of the Religious Orders study, with ages at death ranging from 75 to 98 years old. RESULTS: Participants clinically diagnosed with AD had lower vascular levels of α-SMA, PDGFRß and CD13. These reductions were correlated with lower cognitive scores for global cognition, episodic and semantic memory, perceptual speed and visuospatial ability. In addition, α-SMA, PDGFRß and CD13 were negatively correlated with vascular Aß40 concentrations. Vascular levels of BMC markers were also inversely correlated with insoluble cleaved phosphorylated transactive response DNA binding protein 43 (TDP-43) (25 kDa) and positively correlated with soluble cleaved phosphorylated TDP-43 (35 kDa) in cortical homogenates, suggesting strong association between BMC loss and cleaved phosphorylated TDP-43 aggregation. CONCLUSIONS: The results of this study highlight a loss of BMC in AD. The associations between α-SMA, PDGFRß and CD13 vascular levels with cognitive scores, TDP-43 aggregation and cerebrovascular accumulation of Aß in the parietal cortex suggest that BMC loss contributes to both AD symptoms and pathology, further strengthening the link between cerebrovascular defects and dementia.

Loading efficacy and binding analysis of retinoids with milk proteins: a short review.

In this review, the loading efficacies of retinoids with milk proteins are investigated. It has been shown that milk proteins ß-lactoglobulin, α-, and ß-caseins bind retinol and retinoic acid via hydrophobic, hydrophilic, and H-bonding contacts causing minor alterations of protein secondary structure. Hydrophobic contact is predominant in retinoid-protein conjugation and several amino acids are involved in complex formation, stabilized by H-bonding network. Loading efficacy of retinoid was about 30-50% with retinol forming more stable protein conjugates. Milk proteins can transport retinoid to target molecules.

Folic acid delivery by serum proteins: loading efficacy and protein morphology.

The loading efficacy of folic acid with serum proteins human serum albumin (HSA), bovine serum albumin (BSA), and beta-lactoglobulin (ß-LG) was analyzed and the effect of acid conjugation on protein morphology was determined. Structural analysis showed that folic acid binds HSA, BSA, and ß-LG via hydrophilic, hydrophobic, and H-bonding contacts with BSA forming more stable conjugates than HSA and ß-LG. Molecular modeling showed the presence of several H-bonding systems, stabilizing acid-protein conjugates. Folic acid conjugation alters protein conformation by major alterations of α-helix and ß-sheet. TEM images showed major protein morphological changes inducing protein aggregation upon acid interaction. The results show that serum proteins can deliver folic acid to target molecules.

Review on the binding of anticancer drug doxorubicin with DNA and tRNA: Structural models and antitumor activity.

In this review, we have compared the results of multiple spectroscopic studies and molecular modeling of anticancer drug doxorubicin (DOX) bindings to DNA and tRNA. DOX was intercalated into DNA duplex, while tRNA binding is via major and minor grooves. DOX-DNA intercalation is close to A-7, C-5, *C-19 (H-bonding with DOX NH2 group), G-6, T-8 and T-18 with the free binding energy of -4.99kcal/mol. DOX-tRNA groove bindings are near A-29, A-31, A-38, C-25, C-27, C-28, *G-30 (H-bonding) and U-41 with the free binding energy of -4.44kcal/mol. Drug intercalation induced a partial B to A-DNA transition, while tRNA remained in A-family structure. The structural differences observed between DOX bindings to DNA and tRNA can be the main reasons for drug antitumor activity. The results of in vitro MTT assay on SKC01 colon carcinoma are consistent with the observed DNA structural changes. Future research should be focused on finding suitable nanocarriers for delivery of DOX in vivo in order to exploit the full capacity of this very important anticancer drug.

Structural modeling for DNA binding to antioxidants resveratrol, genistein and curcumin.

Several models are presented here for the bindings of the antioxidant polyphenols resveratrol, genistein and curcumin with DNA in aqueous solution at physiological conditions. Multiple spectroscopic methods and molecular modeling were used to locate the binding sites of these polyphenols with DNA duplex. Structural models showed that intercalation is more stable for resveratrol and genistein than groove bindings, while curcumin interaction is via DNA grooves. Docking showed more stable complexes formed with resveratrol and genistein than curcumin with the free binding energies of -4.62 for resveratrol-DNA (intercalation), -4.28 for resveratrol-DNA (groove binding), -4.54 for genistein-DNA (intercalation), -4.38 for genistein-DNA (groove binding) and -3.84 kcal/mol for curcumin-DNA (groove binding). The free binding energies show polyphenol-DNA complexation is spontaneous at room temperature. At high polyphenol concentration a major DNA aggregation occurred, while biopolymer remained in B-family structure.

Locating the binding sites of antioxidants resveratrol, genistein and curcumin with tRNA.

We located the binding sites of antioxidants resveratrol, genistein and curcumin on tRNA in aqueous solution at physiological conditions using constant tRNA concentration and various polyphenol contents. FTIR, UV-visible, CD spectroscopic methods and molecular modeling were used to determine polyphenol binding sites, the binding constant and the effects of polyphenol complexation on tRNA conformation and particle formation. Structural analysis showed that polyphenols bind tRNA via G-C and A-U base pairs through hydrophilic, hydrophobic and H-bonding contacts with overall binding constants of K(res-tRNA)=8.95(±0.80)×10(3) M(-1), K(gen-tRNA)=3.07(±0.5)×10(3) M(-1) and K(cur-tRNA)=1.55(±0.3)×10(4) M(-1). Molecular modeling showed the participation of several nucleobases in polyphenol-tRNA adduct formation with free binding energy of -4.43 for resveratrol, -4.26 kcal/mol for genistein and -4.84 kcal/mol for curcumin, indicating that the interaction process is spontaneous at room temperature. While tRNA remains in A-family structure, major biopolymer aggregation and particle formation occurred at high polyphenol contents.

Folic acid binds DNA and RNA at different locations.

We located multiple binding sites for folic acid on DNA and tRNA at physiological conditions, using FTIR, CD, fluorescence spectroscopic methods and molecular modeling. Structural analysis revealed that folic acid binds DNA and tRNA at multiple sites via hydrophilic, hydrophobic and H-bonding contacts with overall binding constants of Kfolic acid-DNA=1.1 (±0.3)×10(4) M(-1) and Kfolic acid-tRNA=6.4 (±0.5)×10(3) M(-1). Molecular modeling showed the participation of several nucleobases in folic acid complexes with DNA and tRNA, stabilized by H-bonding network. Two types of complexes were located for folic acid-tRNA adducts, one at the major groove and the other with TΨC loop, while acid binding occurs at major and minor grooves of DNA duplex. Folic acid complexation induced more alterations of DNA structure than tRNA.

Breast anticancer drug tamoxifen and its metabolites bind tRNA at multiple sites.

The binding sites of breast anticancer drug tamoxifen and its metabolites with tRNA were located by FTIR, CD, UV-visible, and fluorescence spectroscopic methods and molecular modeling. Structural analysis showed that tamoxifen and its metabolites bind tRNA at several binding sites with overall binding constants of K(tam-tRNA) = 5.2 (± 0.6) × 10(4) M(-1), K(4-hydroxytam-tRNA) = 6.5 ( ± 0.5) × 10(4) M(-1) and K(endox-tRNA) = 1.3 (± 0.2) × 10(4) M(-1). The number of binding sites occupied by drug molecules on tRNA were 1 (tamoxifen), 0.8 (4-hydroxitamoxifen) and 1.2 (endoxifen). Docking showed the participation of several nucleobases in drug-tRNA complexes with the free binding energy of -4.31 (tamoxifen), -4.45 (4-hydroxtamoxifen) and -4.38 kcal/mol (endoxifen). The order of binding is 4-hydroxy-tamoxifen > tamoxifen > endoxifen. Drug binding did not alter tRNA conformation from A-family structure, while biopolymer aggregation occurred at high drug concentration.

Modelling of vitamin A binding to tRNA.

The binding sites of retinol and retinoic acid with tRNA are located in aqueous solution at physiological conditions using constant tRNA concentration and various retinoid contents. FTIR, CD, fluorescence spectroscopic methods and molecular modelling were used to determine retinoid binding sites, the binding constant and the effects of retinol and retinoic acid complexation on tRNA conformation and aggregation. Structural analysis showed that retinol and retinoic acid bind tRNA via G-C and A-U base pairs with overall binding constants of Kret-tRNA=2.0 (±0.40)×10(4)M(-1) and Kretac-tRNA=6.0 (±1)×10(4)M(-1). The number of binding sites occupied by retinoids on tRNA were 1.4 for retinol-tRNA and 1.7 for retinoic acid-tRNA complexes. Hydrophobic interactions were also observed at high retinol and retinoic acid contents. Molecular modelling showed the participation of several nucleobases in retinoid-tRNA complexation with free binding energy of -4.36 for retinol-tRNA and -4.53kcal/mol for retinoic acid-tRNA adducts.

Association of lipids with milk α- and ß-caseins.

UNLABELLED: We report the molecular interaction and the binding sites of cholesterol (CHOL), 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), dioctadecyldimethyl-ammoniumbromide (DDAB), and dioleoylphosphatidylethanolamine (DOPE) with milk α- and ß-caseins in aquous solution at physiological conditions. Fourier transform infrared (FTIR), fluorescence spectroscopic methods and molecular modeling were used to determine the binding sites of lipid-protein complexes and the effect of lipid interaction on the stability and conformation of α- and ß-caseins. Structural analysis showed that lipids bind casein via mainly hydrophobic contact with association constants of KCHOL-α-casein=1.0 (±0.1)×10(4) M(-1), KDOPE-α-casein=5.0 (±0.07)×10(3) M(-1), KDDAB-α-casein=2.0 (±0.06)×10(4) M(-1), KDOTAP-α-casein=1.5 (±0.6)×10(4) M(-1), KCHOL-ß-casein=1.0 (±0.3)×10(4) M(-1), KDOPE-ß-casein=1.5 (±0.06)×10(3) M(-1), KDDAB-ß-casein=1.7 (±0.3)×10(4) M(-1) and KDOTAP-ß-casein=2.1 (±0.5)×10(4) M(-1). The average number of binding sites occupied by lipid molecules on protein (n) were from 0.7 to 1.1. Docking showed different binding sites for α- and ß-caseins toward lipid complexation with the free binding energies from -10 to -13 kcal/mol. Casein conformation was altered by lipid interaction with a reduction of α-helix and ß-sheet and an increase of random coil and turn structure suggesting a partial protein unfolding. ABBREVIATIONS: Cascasein; CHOLcholesterol; DOTAP1,2-dioleoyl-3-trimethylammonium-propane; DDABdioctadecyldimethylammonium bromide; DOPEdioleoylphosphatidylethanolamine; FTIRFourier transform infrared spectroscopy; CDcircular dichroism.

Locating the binding sites of antitumor drug tamoxifen and its metabolites with DNA.

We located the binding sites of antitumor drugs tamoxifen, 4-hydroxytamoxifen and endoxifen with calf-thymus DNA. FTIR, CD, UV-vis and fluorescence spectroscopic methods as well as molecular modeling were used to characterize the drug binding sites, binding constant and the effect of drug binding on DNA stability and conformation. Structural analysis showed that tamoxifen and its metabolites bind DNA via hydrophobic and hydrophilic interactions with overall binding constants of K(tam-DNA)=3.5 (±0.2)×104 M⁻¹, K(4-hydroxytam-DNA)=3.3 (±0.4) × 104 M⁻¹ and K(endox)-DNA=2.8 (±0.8)×104 M⁻¹. The number of binding sites occupied by drug is 1 (tamoxifen), 0.8 (4-hydroxitamoxifen) and 1.2 (endoxifen). Docking showed the participation of several nucleobases in drug-DNA complexes with the free binding energy of -3.85 (tamoxifen), -4.18 (4-hydroxtamoxifen) and -3.74 kcal/mol (endoxifen). The order of binding is 4-hydroxy-tamoxen>tamoxifen>endoxifen. Drug binding did not alter DNA conformation from B-family structure, while major biopolymer aggregation occurred at high drug concentrations. The drug binding mode is correlated with the mechanism of action of antitumor activity of tamoxifen and its metabolites.

Binding sites of resveratrol, genistein, and curcumin with milk α- and ß-caseins.

The binding sites of antioxidant polyphenols resveratrol, genistein, and curcumin are located with milk α- and ß-caseins in aqueous solution. FTIR, CD, and fluorescence spectroscopic methods and molecular modeling were used to analyze polyphenol binding sites, the binding constant, and the effects of complexation on casein stability and conformation. Structural analysis showed that polyphenols bind casein via hydrophilic and hydrophobic interactions with the number of bound polyphenol molecules (n) 1.20 for resveratrol, 1.42 for genistein, and 1.43 for curcumin with α-casein and 1.14 for resveratrol, 1.27 for genistein, and 1.27 for curcumin with ß-casein. The overall binding constants of the complexes formed are K(res-α-casein) = 1.9 (±0.6) × 10(4) M(-1), K(gen-α-casein) = 1.8 (±0.4) × 10(4) M(-1), and K(cur-α-casein) = 2.8 (±0.8) × 10(4) M(-1) with α-casein and K(res-ß-casein) = 2.3 (±0.3) × 10(4) M(-1), K(gen-ß-casein) = 3.0 (±0.5) × 10(4) M(-1), and K(cur-ß-casein) = 3.1 (±0.5) × 10(4) M(-1) for ß-casein. Molecular modeling showed the participation of several amino acids in polyphenol-protein complexes, which were stabilized by the hydrogen bonding network with the free binding energy of -11.56 (resveratrol-α-casein), -12.35 (resveratrol-ß-casein), -9.68 (genistein-α-casein), -9.97 (genistein-ß-casein), -8.89 (curcumin-α-casein), and -10.70 kcal/mol (curcumin-ß-casein). The binding sites of polyphenols are different with α- and ß-caseins. Polyphenol binding altered casein conformation with reduction of α-helix, indicating a partial protein destabilization. Caseins might act as carriers to transport polyphenol in vitro.

Binding of vitamin A with milk α- and ß-caseins.

The binding sites of retinol and retinoic acid with milk α- and ß-caseins were determined, using constant protein concentration and various retinoid contents. FTIR, UV-visible and fluorescence spectroscopic methods as well as molecular modelling were used to analyse retinol and retinoic acid binding sites, the binding constant and the effect of retinoid complexation on the stability and conformation of caseins. Structural analysis showed that retinoids bind caseins via both hydrophilic and hydrophobic contacts with overall binding constants of K(retinol-)(α)(-caseins)=1.21 (±0.4)×10(5) M(-1) and K(retinol-)(ß)(-caseins)=1.11 (±0.5)×10(5) M(-1) and K(retinoic acid-)(α)(-caseins)=6.2 (±0.6)×10(4) M(-1) and K(retinoic acid-)(ß)(-caseins)=6.3 (±0.6)×10(4) M(-1). The number of bound retinol molecules per protein (n) was 1.5 (±0.1) for α-casein and 1.0 (±0.1) for ß-casein, while 1 molecule of retinoic acid was bound in the α- and ß-casein complexes. Molecular modelling showed different binding sites for retinol and retinoic acid on α- and ß-caseins with more stable complexes formed with α-casein. Retinoid-casein complexation induced minor alterations of protein conformation. Caseins might act as carriers for transportation of retinoids to target molecules.

Probing the binding of cationic lipids with dendrimers.

Polycationic polymers are used extensively in biology to disrupt cell membranes and thus enhance the transport of materials into the cell. We report the bindings of several lipids cholesterol (Chol), 1,2-dioleoyl-3-trimethylammonium-propane(DOTAP), dioctadecyldimethylammoniumbromide (DDAB), and dioleoylphosphatidylethanolamine (DOPE) to dendrimers of different compositions such as mPEG-PAMAM (G3), mPEG-PAMAM (G4), and PAMAM (G4) under physiological conditions. FTIR, UV-visible spectroscopic, methods and molecular modeling were used to analyze the lipid binding mode, the binding constant, and the effects of lipid complexation on the dendrimer structure. The structural analysis showed that lipids bind dendrimers through both hydrophilic and hydrophobic contacts with overall binding constants of K(chol-mPEG-G3) = 1.7 × 10(3) M(-1), K(chol-mPEG-PAMAM-G4) = 2.7 × 10(3) M(-1), K(chol-PAMAM-G4) = 1.0 × 10(3) M(-1), K(DOPE-mPEG-G3) = 1.5 × 10(3) M(-1), K(DOPE-mPEG-PAMAM-G4) = 1.6 × 10(3) M(-1), K(DOPE-PAMAM-G4) = 5.3 × 10(2) M(-1), K(DDAB-mPEG-G3) = 1.5 × 10(3) M(-1), K(DDAB-mPEG-PAMAM-G4) = 1.9 × 10(2) M(-1), K(DDAB-PAMAM-G4) = 7.0 × 10(2) M(-1), K(DOTAP-mPEG-G3) = 1.9 × 10(3) M(-1), K(DOTAP-mPEG-PAMAM-G4) = 1.5 × 10(3) M(-1), and K(DOTAP-PAMAM-G4) = 5.7 × 10(2) M(-1). Weaker interaction was observed as dendrimer cationic charges increased. The free binding energies from docking were -5.15 (cholesterol), -5.79 (DDAB), and -5.36 kcal/mol (DOTAP) with the order of stability DDAB-PAMAM-G-4 > DOTAP-PAMAM-G4 > cholesterol-PAMAM-G4, consistent with the spectroscopic results. Dendrimers might act as carriers to transport lipids in vitro.

Locating the binding sites of folic acid with milk α- and ß-caseins.

We located the binding sites of folic acid with milk α- and ß-caseins at physiological conditions, using constant protein concentration and various folic acid contents. FTIR, UV-visible, and fluorescence spectroscopic methods as well as molecular modeling were used to analyze folic acid binding sites, the binding constant, and the effect of folic acid interaction on the stability and conformation of caseins. Structural analysis showed that folic acid binds caseins via both hydrophilic and hydrophobic contacts with overall binding constants of K(folic acid-α-caseins) = 4.8 (±0.6) × 10(4) M(-1) and K(folic acid-ß-caseins) = 7.0 (±0.9) × 10(4) M(-1). The number of bound acid molecules per protein was 1.5 (±0.4) for α-casein and 1.4 (±0.3) for ß-casein complexes. Molecular modeling showed different binding sites for folic acid on α- and ß-caseins. The participation of several amino acids in folic acid-protein complexes was observed, which was stabilized by hydrogen bonding network and the free binding energy of -7.7 kcal/mol (acid-α-casein) and -8.1 kcal/mol (acid-ß-casein). Folic acid complexation altered protein secondary structure by the reduction of α-helix from 35% (free α-casein) to 33% (acid-complex) and 32% (free ß-casein) to 26% (acid-complex) indicating a partial protein destabilization. Caseins might act as carriers for transportation of folic acid to target molecules.

Locating the binding sites of anticancer tamoxifen and its metabolites 4-hydroxytamoxifen and endoxifen on bovine serum albumin.

The breast anticancer drug tamoxifen and its metabolites bind serum albumins. We located the binding sites of tamoxifen, 4-hydroxytamoxifen and endoxifen on bovine serum albumin (BSA). FTIR, CD and fluorescence spectroscopic methods as well as molecular modeling were used to characterize the drug binding mode, binding constant and the effect of drug binding on BSA stability and conformation. Structural analysis showed that tamoxifen and its metabolites bind BSA via hydrophobic and hydrophilic interactions with overall binding constants of K(tam-BSA) = 1.96 (± 0.2)× 10(4)M(-1), K(4-hydroxytam-BSA) = 1.80 (± 0.4)× 10(4)M(-1) and K(endox-BSA) = 8.01 (± 0.8)× 10(3)M(-1). The number of bound drug molecules per protein is 1.7 (tamoxifen), 1.4 (4-hydroxitamoxifen) and 1.13 (endoxifen). The participation of several amino acid residues in drug-protein complexes is stabilized by extended hydrogen bonding network with the free binding energy of -13.47 (tamoxifen), -13.79 (4-hydroxtamoxifen) and -12.72 kcal/mol (endoxifen). The order of binding is 4-hydroxy-tamoxen>tamoxifen>endoxifen. BSA conformation was altered by a major reduction of α-helix from 63% (free BSA) to 41% with tamoxifen, to 39% with 4-hydroxytamoxifen, and to 47% with endoxifen. In addition, an increase in turn and random coil structures was found, suggesting partial protein unfolding. These results suggest that serum albumins might act as carrier proteins for tamoxifen and its metabolites in delivering them to target tissues.

Binding of antitumor tamoxifen and its metabolites 4-hydroxytamoxifen and endoxifen to human serum albumin.

Tamoxifen is extensively metabolized, and several metabolites have been detected in human serum. The aim of this study was to examine the interaction of human serum albumin (HSA) with tamoxifen and its metabolites 4-hydroxytamoxifen and endoxifen at physiological conditions, using constant protein concentration and various drug contents. FTIR, UV-Visible, CD and fluorescence spectroscopic methods as well as molecular modeling were used to analyse drug binding mode, the binding constant and the effects of drug complexation on HSA stability and conformation. Structural analysis showed that tamoxifen and its metabolites bound HSA via both hydrophobic and hydrophilic interactions with overall binding constants of K(tam) = 1.8 (±0.2) × 10(4) M(-1), K(4-hydroxytam) = 1.8 (±0.4) × 10(4) M(-1) and K(endox) = 2.0 (±0.5) × 10(4) M(-1). The number of bound drugs per protein is 1.2 (tamoxifen), 1.7 (4-hydroxitamoxifen) and 1.0 (endoxifen). Structural modeling showed the participation of several amino acid residues in drug-HSA complexation, with extended H-bonding network. HSA conformation was altered by tamoxifen and its metabolites with a major reduction of α-helix and an increase in ß-sheet, random coil and turn structures, indicating a partial protein unfolding. Our results suggest that serum albumins can act as carrier proteins for tamoxifen and its metabolites in delivering them to target tissues.

Folic acid complexes with human and bovine serum albumins.

The interaction of folic acid with human serum (HSA) and bovine serum albumins (BSA) at physiological conditions, using constant protein concentration and various folic acid contents was investigated. FTIR, UV-visible and fluorescence spectroscopic methods as well as molecular modelling were used to analyse folic acid binding sites, the binding constant and the effect on HSA and BSA stability and conformations. Structural analysis showed that folic acid binds HSA and BSA via both hydrophilic and hydrophobic contacts with overall binding constants of Kfolic acid-HSA=8.1 (±0.5)×10(4)M(-1) and Kfolic acid-BSA=1.0 (±0.3)×10(5)M(-1). The number of bound acid molecules per protein was 1.7 (±0.4) for HSA and 1.5 (±0.3) for BSA complexes. Molecular modelling showed participation of several amino acids in folic acid-protein complexes stabilised by hydrogen bonding network. Folic acid complexation altered protein secondary structure by major reduction of α-helix from 59% (free HSA) to 35% (acid-complex) and 62% (free BSA) to 25% (acid-complex) with an increase in random coil, turn and ß-sheet structures indicating protein unfolding. The results suggest that serum albumins might act as carrier proteins for folic acid in delivering it to target molecules.

Biogenic and synthetic polyamines bind bovine serum albumin.

Biogenic polyamines are found to modulate protein synthesis at different levels, while polyamine analogues have shown major antitumor activity in multiple experimental models, including breast cancer. The aim of this study was to examine the interaction of bovine serum albumin (BSA) with biogenic polyamines, spermine and spermidine, and polyamine analogues 3,7,11,15-tetrazaheptadecane x 4 HCl (BE-333) and 3,7,11,15,19-pentazahenicosane x 5 HCl (BE-3333) in aqueous solution at physiological conditions. FTIR, UV-visible, CD, and fluorescence spectroscopic methods were used to determine the polyamine binding mode and the effects of polyamine complexation on protein stability and secondary structure. Structural analysis showed that polyamines bind BSA via both hydrophilic and hydrophobic interactions. Stronger polyamine-protein complexes formed with biogenic than synthetic polyamines with overall binding constants of K(spm) = 3.56 (+/-0.5) x 10(5) M(-1), K(spmd) = 1.77 (+/-0.4) x 10(5) M(-1), K(BE-333) = 1.11 (+/-0.3) x 10(4) M(-1) and K(BE-3333) = 3.90 (+/-0.7) x 10(4) M(-1) that correlate with their positively charged amino group contents. Major alterations of protein conformation were observed with reduction of alpha-helix from 63% (free protein) to 55-33% and increase of turn 12% (free protein) to 28-16% and random coil from 6% (free protein) to 24-17% in the polyamine-BSA complexes, indicating a partial protein unfolding. These data suggest that serum albumins might act as polyamine carrier proteins in delivering polyamine analogues to target tissues.

Resveratrol, genistein, and curcumin bind bovine serum albumin.

We report the complexation of bovine serum albumin (BSA) with resveratrol, genistein, and curcumin, at physiological conditions, using constant protein concentration and various polyphenol contents. FTIR, CD, and fluorescence spectroscopic methods were used to analyze the ligand binding mode, the binding constant, and the effects of complexation on BSA stability and conformation. Structural analysis showed that polyphenols bind BSA via hydrophilic and hydrophobic interactions with the number of bound polyphenol (n) being 1.30 for resveratrol-BSA, 1.30 for genistein-BSA, and 1.0 for curcumin-BSA. The polyphenol-BSA binding constants were K(Res-BSA) = 2.52(+/-0.5) x 10(4) M(-1), K(Gen-BSA) = 1.26(+/-0.3) x 10(4) M(-1), and K(Cur-BSA) = 3.33(+/-0.8) x 10(4) M(-1). Polyphenol binding altered BSA conformation with a major reduction of alpha-helix and an increase in beta-sheet and turn structures, indicating a partial protein unfolding.