Comparison of spectroscopy technologies for improved monitoring of cell culture processes in miniature bioreactors

Cell culture process development requires the screening of large numbers of cell lines and process conditions. The development of miniature bioreactor systems has increased the throughput of such studies; however, there are limitations with their use. One important constraint is the limited number of offline samples that can be taken compared to those taken for monitoring cultures in large‐scale bioreactors. The small volume of miniature bioreactor cultures (15 mL) is incompatible with the large sample volume (600 µL) required for bioanalysers routinely used. Spectroscopy technologies may be used to resolve this limitation. The purpose of this study was to compare the use of NIR, Raman, and 2D‐fluorescence to measure multiple analytes simultaneously in volumes suitable for daily monitoring of a miniature bioreactor system. A novel design‐of‐experiment approach is described that utilizes previously analyzed cell culture supernatant to assess metabolite concentrations under various conditions while providing optimal coverage of the desired design space. Multivariate data analysis techniques were used to develop predictive models. Model performance was compared to determine which technology is more suitable for this application. 2D‐fluorescence could more accurately measure ammonium concentration (RMSE_CV 0.031 g L^?1) than Raman and NIR. Raman spectroscopy, however, was more robust at measuring lactate and glucose concentrations (RMSE_CV 1.11 and 0.92 g L^?1, respectively) than the other two techniques. The findings suggest that Raman spectroscopy is more suited for this application than NIR and 2D‐fluorescence. The implementation of Raman spectroscopy increases at‐line measuring capabilities, enabling daily monitoring of key cell culture components within miniature bioreactor cultures. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:337–346, 2017     

Hepatic 31P‐magnetic resonance spectroscopy identified the impact of melatonin‐pretreated mitochondria in acute liver ischaemia‐reperfusion injury

Acute liver ischaemia‐reperfusion injury (IRI), commonly encountered during liver resection and transplantation surgery, is strongly associated with unfavourable clinical outcome. However, a prompt and accurate diagnosis and the treatment of this entity remain formidable challenges. This study tested the hypothesis that ³¹P‐magnetic resonance spectroscopy (³¹P‐MRS) findings could provide reliable living images to accurately identify the degree of acute liver IRI and melatonin‐pretreated mitochondria was an innovative treatment for protecting the liver from IRI in rat. Adult male SD rats were categorized into group 1 (sham‐operated control), group 2 (IRI only) and group 3 (IRI + melatonin [ie mitochondrial donor rat received intraperitoneal administration of melatonin] pretreated mitochondria [10 mg/per rat by portal vein]). By the end of study period at 72 hours, ³¹P‐MRS showed that, as compared with group 1, the hepatic levels of ATP and NADH were significantly lower in group 2 than in groups 1 and 3, and significantly lower in group 3 than in group 1. The liver protein expressions of mitochondrial‐electron‐transport‐chain complexes and mitochondrial integrity exhibited an identical pattern to ³¹P‐MRS finding. The protein expressions of oxidative stress, inflammatory, cellular stress signalling and mitochondrial‐damaged biomarkers displayed an opposite finding of ³¹P‐MRS, whereas the protein expressions of antioxidants were significantly progressively increased from groups 1 to 3. Microscopic findings showed that the fibrotic area/liver injury score and inflammatory and DNA‐damaged biomarkers exhibited an identical pattern of cellular stress signalling. Melatonin‐pretreated mitochondria effectively protected liver against IRI and ³¹P‐MRS was a reliable tool for measuring the mitochondrial/ATP consumption in living animals.     

Refining phenotype characterization in genetic linkage studies of schizophrenia

Abstract

A definitive replicable genetic linkage for a major locus underlying the susceptibility to schizophrenia has not been identified to date. Although there are several possible explanations for the failure to find linkage in schizophrenia, one major problem is that the range of phenotypic expressions of the genes for schizophrenia has not been clarified. A more refined understanding of the various phenotypic expressions of a gene related to schizophrenia would enhance the power of studies designed to detect a genetic linkage with a major chromosomal locus and would benefit other strategies for understanding the etiology of schizophrenia.

The genes for schizophrenia may be frequently expressed in relatives of schizophrenic patients, although with less severe symptoms than those of chronic schizophrenia. Two series of findings support this notion. Nonschizophrenic relatives of schizophrenic patients demonstrate an increased incidence of nonpsychotic schizophrenia‐like symptoms and traits, and they manifest deficit performances on several different laboratory tests of neurocognitive functioning. A more refined phenotypic expression of a schizophrenia‐related gene may thus be indicated by personality traits and subclinical neurocognitive deficits.

These personality traits and neurocognitive deficits are considered here as possible aids in the identification of affected cases in genetic linkage studies of schizophrenia. Terminology for different indicators of neurocognitive deficits is introduced, and the relative utility of personality traits and indicators of neurocognitive deficit for genetic linkage studies is discussed. As specific examples, schizophrenia‐related personality traits that are unrelated to affective symptoms and performance deficits on tasks of eye tracking and continuous attention are considered for strategies for broadening phenotype characterization without reducing the specificity of affected case identification.     

Study on the interaction between ginsenoside Rh2 and calf thymus DNA by spectroscopic techniques

The interaction between ginsenoside Rh2 (G‐Rh2) and calf thymus DNA (ctDNA) was investigated by spectroscopic methods including UV–vis absorption, fluorescence and circular dichroism (CD) spectroscopy, coupled with DNA melting techniques and viscosity measurements. Stern–Volmer plots at different temperatures proved that the quenching mechanism was a static quenching procedure. The thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS) were calculated to be –22.83 KJ · mol^–1and 15.11 J · mol^–1 · K^–1by van ’t Hoff equation, suggesting that hydrophobic force might play a major role in the binding of G‐Rh2 to ctDNA. Moreover, the fluorescence quenching study with potassium iodide as quencher indicated that the K_SV (Stern–Volmer quenching constant) value for the bound G‐Rh2 with ctDNA was lower than the free G‐Rh2. The relative viscosity of ctDNA increased with the addition of G‐Rh2 and also the ctDNA melting temperature increased in the presence of G‐Rh2. Denatured DNA studies showed that quenching by single‐stranded DNA was less than that by double‐stranded DNA. The observed changes in CD spectra also demonstrated that the intensities of the positive and negative bands decreased with the addition of G‐Rh2. The experimental results suggest that G‐Rh2 molecules bind to ctDNA via an intercalative binding mode. Copyright © 2015 John Wiley & Sons, Ltd.     

β‐amyloid model core peptides: Effects of hydrophobes and disulfides

The mechanism by which a disordered peptide nucleates and forms amyloid is incompletely understood. A central domain of β‐amyloid (Aβ21–30) has been proposed to have intrinsic structural propensities that guide the limited formation of structure in the process of fibrillization. In order to test this hypothesis, we examine several internal fragments of Aβ, and variants of these either cyclized or with an N‐terminal Cys. While Aβ21–30 and variants were always monomeric and unstructured (circular dichroism (CD) and nuclear magnetic resonance spectroscopy (NMRS)), we found that the addition of flanking hydrophobic residues in Aβ16–34 led to formation of typical amyloid fibrils. NMR showed no long‐range nuclear overhauser effect (nOes) in Aβ21–30, Aβ16–34, or their variants, however. Serial ¹H‐¹⁵N‐heteronuclear single quantum coherence spectroscopy, ¹H‐¹H nuclear overhauser effect spectroscopy, and ¹H‐¹H total correlational spectroscopy spectra were used to follow aggregation of Aβ16–34 and Cys‐Aβ16–34 at a site‐specific level. The addition of an N‐terminal Cys residue (in Cys‐Aβ16–34) increased the rate of fibrillization which was attributable to disulfide bond formation. We propose a scheme comparing the aggregation pathways for Aβ16–34 and Cys‐Aβ16–34, according to which Cys‐Aβ16–34 dimerizes, which accelerates fibril formation. In this context, cysteine residues form a focal point that guides fibrillization, a role which, in native peptides, can be assumed by heterogeneous nucleators of aggregation.     

Characterisation of DNA methylation status using spectroscopy (mid‐IR versus Raman) with multivariate analysis

Methylation status plays important roles in the regulation of gene expression and significantly influences the dynamics, bending and flexibility of DNA. The aim of this study was to determine whether attenuated total reflection Fourier‐transform infrared (ATR‐FTIR) or Raman spectroscopy with subsequent multivariate analysis could determine methylation patterning in oligonucleotides variously containing 5‐methylcytosine, cytosine and guanine bases. Applied to Low‐E reflective glass slides, 10 independent spectral acquisitions were acquired per oligonucleotide sample. Resultant spectra were baseline‐corrected and vector normalised over the 1750 cm^–1–760 cm^–1 (for ATR‐FTIR spectroscopy) or the 1750 cm^–1–600 cm^–1 (for Raman spectroscopy) regions. Data were then analysed using principal component analysis (PCA) coupled with linear discriminant analysis (LDA). Exploiting this approach, biomolecular signatures enabling sensitive and specific discrimination of methylation patterning were derived. For DNA sequence and methylation analysis, this approach has the potential to be an important tool, especially when material is scarce. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Energy and greenhouse gas balance of bioenergy production from poplar and willow: a review

Short‐rotation woody crops (SRWC) such as poplar and willow are an important source of renewable energy. They can be converted into electricity and/or heat using conventional or modern biomass technologies. In recent years many studies have examined the energy and greenhouse gas (GHG) balance of bioenergy production from poplar and willow using various approaches. The outcomes of these studies have, however, generated controversy among scientists, policy makers, and the society. This paper reviews 26 studies on energy and GHG balance of bioenergy production from poplar and willow published between 1990 and 2009. The data published in the reviewed literature gave energy ratios (ER) between 13 and 79 for the cradle‐to‐farm gate and between 3 and 16 for cradle‐to‐plant assessments, whereas the intensity of GHG emissions ranged from 0.6 to 10.6 g CO₂ Eq MJ_biomass^?1 and 39 to 132 g CO₂ Eq kWh^?1. These values vary substantially among the reviewed studies depending on the system boundaries and methodological assumptions. The lack of transparency hampers meaningful comparisons among studies. Although specific numerical results differ, our review revealed a general consensus on two points: SRWC yielded 14.1–85.9 times more energy than coal (ER_coal～0.9) per unit of fossil energy input, and GHG emissions were 9–161 times lower than those of coal (GHG_coal～96.8). To help to reduce the substantial variability in results, this review suggests a standardization of the assumptions about methodological issues. Likewise, the development of a widely accepted framework toward a reliable analysis of energy in bioenergy production systems is most needed.     

Resonance energy transfer,pH‐induced folded states and the molecular interaction of human serum albumin and icariin

Icariin is a flavonol glycoside with a wide range of pharmacological and biological activities. The pharmacological and biological functions of flavonoid compounds mainly originate from their binding to proteins. The mode of interaction of icariin with human serum albumin (HSA) has been characterized by fluorescence spectroscopy and far‐ and near‐UV circular dichroism (CD) spectroscopy under different pH conditions. Fluorescence quenching studies showed that the binding affinity of icariin with HSA in the buffer solution at different pH values is: K_a (pH 4.5) > K_a (pH 3.5) > K_a (pH 9.0) > K_a (pH 7.0). Red‐edge excitation shift (REES) studies revealed that pH had an obvious effect on the mobility of the tryptophan microenvironment and the addition of icariin made the REES effect more distinct. The static quenching mechanism and number of binding sites (n ≈ 1) were obtained from fluorescence data at three temperatures (298, 304 and 310 K). Both ?H⁰ < 0 and ??⁰ < 0 suggested that hydrogen bonding and van der Waal's interaction were major driving forces in the binding mechanism, and this was also confirmed by the molecular simulation results. The distance r between the donor (HSA) and the acceptor (icariin) was calculated based on Förster non‐radiation energy transfer theory. We found that pH had little impact on the energy transfer between HSA and icariin. Far‐ and near‐UV CD spectroscopy studies further indicated the influence of pH on the complexation process and the alteration in the protein conformation upon binding. Copyright © 2015 John Wiley & Sons, Ltd.     

The interaction of ammonia and xenon with the imidazole glycerol phosphate synthase from Thermotoga maritima as detected by NMR spectroscopy

The imidazole glycerol phosphate (ImGP) synthase from the hyperthermophilic bacterium Thermotoga maritima is a 1:1 complex of the glutaminase subunit HisH and the cyclase subunit HisF. It has been proposed that ammonia generated by HisH is transported through a channel to the active site of HisF, which generates intermediates of histidine (ImGP) and de novo biosynthesis of 5‐aminoimidazole‐4‐carboxamideribotide. Solution NMR spectroscopy of ammonium chloride‐titrated samples was used to study the interaction of NH₃ with amino acids inside this channel. Although numerous residues showed ¹⁵N chemical shift changes, most of these changes were caused by nonspecific ionic strength effects. However, several interactions appeared to be specific. Remarkably, the amino acid residue Thr 78—which is located in the central channel—shows a large chemical shift change upon titration with ammonium chloride. This result and the reduced catalytic activity of the Thr78Met mutant indicate a special role of this residue in ammonia channeling. To detect and further characterize internal cavities in HisF, which might for example contribute to ammonia channeling, the interaction of HisF with the noble gas xenon was analyzed by solution NMR spectroscopy using ¹H‐¹⁵N HSQC experiments. The results indicate that HisF contains three distinct internal cavities, which could be identified by xenon‐induced chemical shift changes of the neighboring amino acid residues. Two of these cavities are located at the active site at opposite ends of the substrate N′‐[(5′‐phosphoribulosyl)formimino]‐5‐aminoimidazole‐4‐carboxamide‐ribonucleotide (PRFAR) binding groove. The third cavity is located in the interior of the central β‐barrel of HisF and overlaps with the putative ammonia transport channel.     

Comparison of interactions between human serum albumin and silver nanoparticles of different sizes using spectroscopic methods

Three different sizes (15.9 ± 2.1 nm, 26.4 ± 3.2 nm and 39.8 ± 4.0 nm, respectively) of citrate‐coated silver nanoparticles (SNPs) have been synthesized and characterized. The interactions of the synthesized SNPs with human serum albumin (HSA) at physiological pH have been systematically studied by UV‐vis absorption spectroscopy, fluorescence spectroscopy, synchronous fluorescence spectroscopy, three‐dimensional fluorescence spectroscopy and circular dichroism (CD) spectroscopy. The results indicate that the SNPs can bind to HSA with high affinity and quench the intrinsic fluorescence of HSA. The binding constants and quenching rate constants were calculated. The apparent association constants (K_app) values are 2.14 × 10⁴ M^–1 for 15.9 nm SNP, 1.65 × 10⁴ M^–1 for 26.4 nm SNP and 1.37 × 10⁴ M^–1 for 39.8 nm SNP, respectively. The values of binding constant obtained from the fluorescence quenching data match well with that determined from the absorption spectral changes. These results suggest that the smaller SNPs have stronger interactions to HSA than the larger ones at the same concentrations. Synchronous fluorescence, three‐dimensional fluorescence and CD spectroscopy studies show that the synthesized SNPs can induce slight conformational changes in HSA. Copyright © 2014 John Wiley & Sons, Ltd.     

Interaction of cyproheptadine hydrochloride with human serum albumin using spectroscopy and molecular modeling methods

The interaction between cyproheptadine hydrochloride (CYP) and human serum albumin (HSA) was investigated by fluorescence spectroscopy, UV–vis absorption spectroscopy, Fourier transform infrared spectroscopy (FT‐IR) and molecular modeling at a physiological pH (7.40). Fluorescence of HSA was quenched remarkably by CYP and the quenching mechanism was considered as static quenching since it formed a complex. The association constants K_a and number of binding sites n were calculated at different temperatures. According to Förster's theory of non‐radiation energy transfer, the distance r between donor (human serum albumin) and acceptor (cyproheptadine hydrochloride) was obtained. The effect of common ions on the binding constant was also investigated. The effect of CYP on the conformation of HSA was analyzed using FT‐IR, synchronous fluorescence spectroscopy and 3D fluorescence spectra. The thermodynamic parameters ΔH and ΔS were calculated to be ?14.37 kJ mol^?1 and 38.03 J mol^?1 K^?1, respectively, which suggested that hydrophobic forces played a major role in stabilizing the HSA‐CYP complex. In addition, examination of molecular modeling indicated that CYP could bind to site I of HSA and that hydrophobic interaction was the major acting force, which was in agreement with binding mode studies. Copyright © 2012 John Wiley & Sons, Ltd.     

The clinical significance of duration of untreated psychosis: an umbrella review and random‐effects meta‐analysis

The idea that a longer duration of untreated psychosis (DUP) leads to poorer outcomes has contributed to extensive changes in mental health ser­vices worldwide and has attracted considerable research interest over the past 30 years. However, the strength of the evidence underlying this notion is unclear. To address this issue, we conducted an umbrella review of available meta‐analyses and performed a random‐effects meta‐analysis of primary studies. MEDLINE, Web of Science, PsycINFO and EMBASE were searched from inception to September 3, 2020 to identify relevant meta‐analyses of studies including patients with schizophrenia spectrum disorders, first‐episode psychosis, or affective and non‐affective psychosis. Thirteen meta‐analyses were included, corresponding to 129 individual studies with a total sample size of 25,657 patients. We detected potential violations of statistical assumptions in some of these meta‐analyses. We therefore conducted a new random‐effects meta‐analysis of primary studies. The association between DUP and each outcome was graded according to a standardized classification into convincing, highly suggestive, suggestive, weak, or non‐significant. At first presentation, there was suggestive evidence for a relationship between longer DUP and more severe negative symptoms (beta=–0.07, p=3.6×10^–5) and higher chance of previous self‐harm (odds ratio, OR=1.89, p=1.1×10^–5). At follow‐up, there was highly suggestive evidence for a relationship between longer DUP and more severe positive symptoms (beta=–0.16, p=4.5×10^–8), more severe negative symptoms (beta=–0.11, p=3.5×10^–10) and lower chance of remission (OR=2.16, p=3.0×10^–10), and suggestive evidence for a relationship between longer DUP and poorer overall functioning (beta=–0.11, p=2.2×10^–6) and more severe global psychopathology (beta=–0.16, p=4.7×10^–6). Results were unchanged when analysis was restricted to prospective studies. These effect sizes are clinically meaningful, with a DUP of four weeks predicting >20% more severe symptoms at follow‐up relative to a DUP of one week. We conclude that DUP is an important prognostic factor at first presentation and predicts clinically relevant outcomes over the course of illness. We discuss conceptual issues in DUP research and methodological limitations of current evidence, and provide recommendations for future research.     

How do glial-neuronal interactions fit into current neurotransmitter hypotheses of schizophrenia?

Evidence is accumulating that the exclusive dopamine hypothesis of schizophrenia has to be abandoned. Instead, a more integrative approach combines different neurotransmitter systems, in which glutamatergic, GABAergic and dopaminergic pathways interact. This paradigm shift coincides with the recognition that, while typical and modern atypical antipsychotic drugs have efficiently controlled the dramatic psychotic symptoms of schizophrenia, their impact on negative and cognitive symptoms is negligible. Indeed, cognitive decline is now believed to represent the core of schizophrenic morbidity and in this context, impairment of glutamate and more specifically NMDA function is of major importance. Given that astrocytes are important in controlling glutamate homeostasis, it is necessary to assign a significant role to glial-neuronal interactions in the pathophysiology of schizophrenia. Indeed, recent data from several animal and human studies corroborate this notion. This review outlines current neurotransmitter hypotheses and evidence for glial impairment in schizophrenia. Furthermore, findings from recent studies of (13)C nuclear magnetic resonance spectroscopy in experimental models of schizophrenia and NMDA hypofunction are presented and their implications for future research on glial-neuronal interactions discussed.     

Hen egg white lysozyme fibrillation: a deep‐UV resonance Raman spectroscopic study

Amyloid fibrils are associated with numerous degenerative diseases. The molecular mechanism of the structural transformation of native protein to the highly ordered cross‐β structure, the key feature of amyloid fibrils, is under active investigation. Conventional biophysical methods have limited application in addressing the problem because of the heterogeneous nature of the system. In this study, we demonstrated that deep‐UV resonance Raman (DUVRR) spectroscopy in combination with circular dichroism (CD) and intrinsic tryptophan fluorescence allowed for quantitative characterization of protein structural evolution at all stages of hen egg white lysozyme fibrillation in vitro. DUVRR spectroscopy was found to be complimentary to the far‐UV CD because it is (i) more sensitive to β ‐sheet than to α ‐helix, and (ii) capable of characterizing quantitatively inhomogeneous and highly light‐scattering samples. In addition, phenylalanine, a natural DUVRR spectroscopic biomarker of protein structural rearrangements, exhibited substantial changes in the Raman cross section of the 1000‐cm^–1 band at various stages of fibrillation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

精神分裂症易感基因的研究进展

精神分裂症迄今病因未明,家系研究、双生子与寄养子的研究显示了精神分裂症的遗传倾向,各国学者开展了许多寻找其致病基因的研究工作。已经有大量关于精神分裂症易感基因的报道,有些结果也在后续试验中取得了较好的重复性。本文主要就精神分裂症易感基因的研究近况做一综述。     

Association of AKT1 gene variants and protein expression in both schizophrenia and bipolar disorder

The AKT1 gene has been associated with the genetic aetiology of schizophrenia. Following the overlap model of bipolar disorder and schizophrenia, we aimed to investigate AKT1 genetic variants and protein expression in both diseases. A total of 679 subjects with European ancestry were included: 384 with schizophrenia, 130 with bipolar disorder and 165 controls. Six single nucleotide polymorphisms (SNPs) were investigated for association with the diseases using single‐ and multi‐locus analyses. AKT1 and AKT2 protein levels were measured in post‐mortem brain tissues from ante‐mortem diagnosed schizophrenia (n = 30) and bipolar disorder subjects (n = 12) and matched controls. The analysis identified a significant global distortion in schizophrenia (P = 0.0026) and a weak association in bipolar disorder (P = 0.046). A sliding window procedure showed a five‐SNP haplotype (TCGAG) to be associated with schizophrenia (P = 1.22 × 10^?4) and bipolar disorder (P = 0.0041) and a four‐SNP haplotype (TCGA) with the combined sample (1.73 × 10^?5). On the basis of selected genotypes, a significant difference in protein expression emerged between subjects (P < 0.02). In conclusion, our findings, by showing the involvement of the AKT1 gene in both schizophrenia and bipolar disorder, support the role of AKT1 in the genetics of both disorders and add support to the view that there is some genetic overlap between them.     

NMR structural analysis of Sleeping Beauty transposase binding to DNA

The Sleeping Beauty (SB) transposon is the most widely used DNA transposon in genetic applications and is the only DNA transposon thus far in clinical trials for human gene therapy. In the absence of atomic level structural information, the development of SB transposon relied primarily on the biochemical and genetic homology data. While these studies were successful and have yielded hyperactive transposases, structural information is needed to gain a mechanistic understanding of transposase activity and guides to further improvement. We have initiated a structural study of SB transposase using Nuclear Magnetic Resonance (NMR) and Circular Dichroism (CD) spectroscopy to investigate the properties of the DNA‐binding domain of SB transposase in solution. We show that at physiologic salt concentrations, the SB DNA‐binding domain remains mostly unstructured but its N‐terminal PAI subdomain forms a compact, three‐helical structure with a helix‐turn‐helix motif at higher concentrations of NaCl. Furthermore, we show that the full‐length SB DNA‐binding domain associates differently with inner and outer binding sites of the transposon DNA. We also show that the PAI subdomain of SB DNA‐binding domain has a dominant role in transposase's attachment to the inverted terminal repeats of the transposon DNA. Overall, our data validate several earlier predictions and provide new insights on how SB transposase recognizes transposon DNA.     

Biomolecular interaction study of hydralazine with bovine serum albumin and effect of β‐cyclodextrin on binding by fluorescence, 3D,synchronous, CD,and Raman spectroscopic methods

Spectrofluoremetric technique was employed to study the binding behavior of hydralazine with bovine serum albumin (BSA) at different temperatures. Binding study of bovine serum albumin with hydralazine has been studied by ultraviolet–visible spectroscopy, fluorescence spectroscopy and confirmed by three‐dimensional, synchronous, circular dichroism, and Raman spectroscopic methods. Effect of β‐cyclodextrin on binding was studied. The experimental results showed a static quenching mechanism in the interaction of hydralazine with bovine serum albumin. The binding constant and the number of binding sites are calculated according to Stern–Volmer equation. The thermodynamic parameters ?H^o, ?G^o, ?S^o at different temperatures were calculated. These indicated that the hydrogen bonding and weak van der Waals forces played an important role in the interaction. Based on the Förster's theory of non‐radiation energy transfer, the binding average distance, r, between the donor (BSA) and acceptor (hydralazine) was evaluated and found to be 3.95 nm. Spectral results showed that the binding of hydralazine to BSA induced conformational changes in BSA. The effect of common ions on the binding of hydralazine to BSA was also examined. Copyright © 2016 John Wiley & Sons, Ltd.