Electrophoretic analysis of the major polypeptides of the human erythrocyte membrane

Physiological Significance of Ion Transporters and Channels in the Stomach and Pathophysiological Relevance in Gastric Cancer

Gastric cancer (GC) is a highly invasive and fatal malignant disease that accounts for 5.7% of new global cancer cases and is the third leading cause of cancer-related death. Acid/base homeostasis is critical for organisms because protein and enzyme function, cellular structure, and plasma membrane permeability change with pH. Various ion transporters are expressed in normal gastric mucosal epithelial cells and regulate gastric acid secretion, ion transport, and fluid absorption, thereby stabilizing the differentiation and homeostasis of gastric mucosal epithelial cells. Ion transporter dysfunction results in disordered ion transport, mucosa barrier dysfunction, and acid/base disturbances, causing gastric acid-related diseases such as chronic atrophic gastritis (CAG) and GC. This review summarizes the physiological functions of multiple ion transporters and channels in the stomach, including Cl⁻ channels, Cl⁻/HCO₃⁻ exchangers, sodium/hydrogen exchangers (NHEs), and potassium (K⁺) channels, and their pathophysiological relevance in GC.

Isolation and Characterization of a Novel Sialoglycopeptide Promoting Osteogenesis from Gadus morhua Eggs

Gadus morhua eggs contain several nutrients, including polyunsaturated fatty acids, lecithin and glycoproteins. A novel sialoglycopeptide from the eggs of G. morhua (Gm-SGPP) was extracted with 90% phenol and purified by Q Sepharose Fast Flow (QFF) ion exchange chromatography, followed by S-300 gel filtration chromatography. Gm-SGPP contained 63.7% carbohydrate, 16.2% protein and 18.6% N-acetylneuraminic acid. High-performance size exclusion chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that Gm-SGPP is a 7000-Da pure sialoglycopeptide. β-elimination reaction suggested that Gm-SGPP contained N-glycan units. Amino acid N-terminal sequence analysis indicated the presence of Ala-Ser-Asn-Gly-Thr-Gln-Ala-Pro amino acid sequence. Moreover, N-glycan was connected at the third Asn location of the peptide chain through GlcNAc. Gm-SGPP was composed of D-mannose, D-glucuronic acid and D-galactose. Fourier transform-infrared spectroscopy (FT-IR), ¹H-nuclear magnetic resonance spectroscopy (¹H-NMR) and methylation analysis were performed to reveal the structure profile of Gm-SGPP. In vitro results showed that the proliferation activity of MC3T3-E1 cells was significantly promoted by Gm-SGPP. In vivo data revealed that Gm-SGPP increased the calcium and phosphorus content of tibias and promoted longitudinal bone growth in adolescent rats.

Effects of Polyphenol Compounds and Nitrogen Oxide Donors on Lipid Oxidation, Membrane-Skeletal Proteins, and Erythrocyte Structure under Hypoxia

This study shows that membrane-associated cytoskeletal protein structures and the erythrocyte morphology undergo profound changes during hypoxia. Hypoxia also intensified oxidative processes in the lipid phase of the bilayer of red blood cell membranes. Sodium nitroprusside impaired the morphology of red blood cells and altered quantitative and qualitative composition of membrane-skeletal proteins. The findings suggest that hypoxia causes changes at all levels of red blood cell organization, which can cause the functional disorders of hemoglobin oxygen-transporting properties and, eventually, the complete degradation of red blood cells. The use of flavonoids has a protective effect against hypoxia.

Deciphering molecular heterogeneity of Indian families with hereditary spherocytosis using targeted next-generation sequencing: First South Asian study

Defects in various erythrocyte membrane proteins genes (ankyrin, band-3, β- and α-spectrin and protein 4·2) can cause hereditary spherocytosis (HS). This molecular heterogeneity of HS, together with co-inherited genetic modifiers, results in marked phenotypic variability among patients. We studied the molecular spectrum and genotype-phenotype correlations in 73 families (with 113 patients) with HS. Deleterious variants including nonsense (42%), deletions (18%), splice site (20%), missense (10%) and duplication/insertion (10%) were found in 47 patients. The variants detected included sporadic and dominantly-inherited defects in ANK1 (53·2%), SPTB (36·2%) and SLC4A1 (4·2%). Compound heterozygous variants in SPTA1 (6·4%) showed autosomal recessive inheritance. Alpha-spectrin variants were associated with severe anaemia and splenectomy alleviated symptoms. Co-inherited glucose-6-phosphate dehydrogenase (G6PD) deficiency was found in 15%. G6PD variants (n = 5) led to greater transfusion requirements (1-8 times) in males with HS. Homozygosity (41%) for the promoter variant of UGT1A1 (Gilbert syndrome) led to a significantly higher mean bilirubin level (126·54 µmol/l) with a higher frequency of cholelithiasis (30%) (P < 0·001). This first-ever south Asian study on the molecular spectrum of HS found ANK1 and SPTB genes variants to be the commonest with inheritance being sporadic/dominant. Next-generation sequencing provided a relatively sensitive and rapid tool for molecular diagnosis with a diagnostic yield of 64·4%.

New methods for purification of Paralichthys olivaceus lipovitellin and immunoassay-based detection of vitellogenin

Increasing levels of estrogenic pollution in marine environments has made the development of reliable biological detection techniques urgently needed. In this study, Japanese flounder (Paralichthys olivaceus) lipovitellin (Lv) was purified and used to establish three immunological methods for the detection of vitellogenin (Vtg), a biomarker for environmental estrogens. Firstly, five different methods were employed to purify Lv, among which water-precipitation was the fastest and easiest way to purify Lv. Japanese flounder Lv was characterized as a phospholipoglycoprotein with a molecular weight of ∼369 kDa. Using purified Lv and its specific polyclonal antibody, a sandwich enzyme-linked immunosorbent assay (ELISA) was developed. This assay had a working range from 7.8 to 250 ng/mL and a detection limit of 3.1 ng/mL. Furthermore, we developed an immunohistochemistry (IHC) and an immunofluorescence (IF) assay, both of which allowed visual detection of liver Vtg. Finally, Vtg induction in plasma and liver of juvenile Japanese flounders exposed to 17β-ethinylestradiol (EE₂) was measured using these three methods. Exposure to 10 and 50 ng/L EE₂ significantly increased plasma Vtg levels, and obvious positive fluorescence signals were observed near the liver sinusoidal vessels. These results confirmed that the methods developed effectively detected estrogenic activity of exogenous chemicals. Therefore, this study provides reliable methodologies for biomonitoring of estrogenic pollution in marine environments.

Monoclonal Antibody AP3 Binds Galactomannan Antigens Displayed by the Pathogens Aspergillus flavus, A. fumigatus, and A. parasiticus

Aspergillus fumigatus and A. flavus are the fungal pathogens responsible for most cases of invasive aspergillosis (IA). Early detection of the circulating antigen galactomannan (GM) in serum allows the prompt application of effective antifungal therapy, thus improving the survival rate of IA patients. However, the use of monoclonal antibodies (mAbs) for the diagnosis of IA is often associated with false positives due to cross-reaction with bacterial polysaccharides. More specific antibodies are therefore needed. Here we describe the characterization of the Aspergillus-specific mAb AP3 (IgG1κ), including the precise identification of its corresponding antigen. The antibody was generated using A. parasiticus cell wall fragments and was shown to bind several Aspergillus species. Immunofluorescence microscopy revealed that AP3 binds a cell wall antigen, but immunoprecipitation and enzyme-linked immunosorbent assays showed that the antigen is also secreted into the culture medium. The inability of AP3 to bind the A. fumigatus galactofuranose (Galf )-deficient mutant ΔglfA confirmed that Galf residues are part of the epitope. Several lines of evidence strongly indicated that AP3 recognizes the Galf residues of O-linked glycans on Aspergillus proteins. Glycoarray analysis revealed that AP3 recognizes oligo-[β-D-Galf-1,5] sequences containing four or more residues with longer chains more efficiently. We also showed that AP3 captures GM in serum, suggesting it may be useful as a diagnostic tool for patients with IA.

Modeling neuronopathic storage diseases with patient-derived culture systems

Lysosomes are organelles involved in the degradation and recycling of macromolecules, and play a critical role in sensing metabolic information in the cell. A class of rare metabolic diseases called lysosomal storage disorders (LSD) are characterized by lysosomal dysfunction and the accumulation of macromolecular substrates. The central nervous system appears to be particularly vulnerable to lysosomal dysfunction, since many LSDs are characterized by severe, widespread neurodegeneration with pediatric onset. Furthermore, variants in lysosomal genes are strongly associated with some common neurodegenerative disorders such as Parkinson's disease (PD). To better understand disease pathology and develop novel treatment strategies, it is critical to study the fundamental molecular disease mechanisms in the affected cell types that harbor endogenously expressed mutations. The discovery of methods for reprogramming of patient-derived somatic cells into induced pluripotent stem cells (iPSCs), and their differentiation into distinct neuronal and glial cell types, have provided novel opportunities to study mechanisms of lysosomal dysfunction within the relevant, vulnerable cell types. These models also expand our ability to develop and test novel therapeutic targets. We discuss recently developed methods for iPSC differentiation into distinct neuronal and glial cell types, while addressing the need for meticulous experimental techniques and parameters that are essential to accurately identify inherent cellular pathologies. iPSC models for neuronopathic LSDs and their relationship to sporadic age-related neurodegeneration are also discussed. These models should facilitate the discovery and development of personalized therapies in the future.

Aberrant splicing contributes to severe α-spectrin-linked congenital hemolytic anemia

The etiology of severe hemolytic anemia in most patients with recessive hereditary spherocytosis (rHS) and the related disorder hereditary pyropoikilocytosis (HPP) is unknown. Whole exome sequencing of DNA from probands of 24 rHS or HPP kindreds identified numerous mutations in erythrocyte membrane α-spectrin (SPTA1). Twenty-eight mutations were novel, with null alleles frequently found in trans to missense mutations. No mutations were identified in a third of SPTA1 alleles (17/48). Whole genome sequencing revealed linkage disequilibrium between the common rHS-linked α-spectrinBug Hill polymorphism and a rare intron 30 variant in all 17 mutation-negative alleles. In vitro minigene studies and in vivo splicing analyses revealed the intron 30 variant changes a weak alternate branch point (BP) to a strong BP. This change leads to increased utilization of an alternate 3' splice acceptor site, perturbing normal α-spectrin mRNA splicing and creating an elongated mRNA transcript. In vivo mRNA stability studies revealed the newly created termination codon in the elongated transcript activates nonsense mediated decay leading to spectrin deficiency. These results demonstrate a unique mechanism of human genetic disease contributes to the etiology of a third of cases of rHS, facilitating diagnosis and treatment of severe anemia, and identifying a new target for therapeutic manipulation.

Identification of Candidate Ergosterol-Responsive Proteins Associated with the Plasma Membrane of Arabidopsis thaliana

The impact of fungal diseases on crop production negatively reflects on sustainable food production and overall economic health. Ergosterol is the major sterol component in fungal membranes and regarded as a general elicitor or microbe-associated molecular pattern (MAMP) molecule. Although plant responses to ergosterol have been reported, the perception mechanism is still unknown. Here, Arabidopsis thaliana protein fractions were used to identify those differentially regulated following ergosterol treatment; additionally, they were subjected to affinity-based chromatography enrichment strategies to capture and categorize ergosterol-interacting candidate proteins using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Mature plants were treated with 250 nM ergosterol over a 24 h period, and plasma membrane-associated fractions were isolated. In addition, ergosterol was immobilized on two different affinity-based systems to capture interacting proteins/complexes. This resulted in the identification of defense-related proteins such as chitin elicitor receptor kinase (CERK), non-race specific disease resistance/harpin-induced (NDR1/HIN1)-like protein, Ras-related proteins, aquaporins, remorin protein, leucine-rich repeat (LRR)- receptor like kinases (RLKs), G-type lectin S-receptor-like serine/threonine-protein kinase (GsSRK), and glycosylphosphatidylinositol (GPI)-anchored protein. Furthermore, the results elucidated unknown signaling responses to this MAMP, including endocytosis, and other similarities to those previously reported for bacterial flagellin, lipopolysaccharides, and fungal chitin.

Characterization of the 6-O-acetylated lipoglucuronomannogalactan a novel Cryptococcus neoformans cell wall polysaccharide

Glucuronoxylomannogalactans (GXMGals) are characteristic capsular polysaccharides produced by the opportunistic fungus C. neoformans, which are implicated in cryptococcal virulence, via impairment of the host immune response. We determined for the first time the structure of a lipoglucuronomannogalactan (LGMGal), isolated from the surface of a mutant C. neoformans carrying a deletion in the UDP-GlcA decarboxylase gene. Monosaccharide composition and methylation analyses, as well as nuclear magnetic resonance spectroscopy were employed in discerning the structure. Our results show that the polysaccharide structure of the LGMGal differs from GXMGal by the absence of xylose and 2-O-acetylated mannose residues. LGMGal consists of a galactan main chain -[-6-α-Gal-]-, where every second Gal residue is substituted at O-3 with an oligosaccharide α-Man6OAc-3-α-Man-4-(β-GlcA-3)-β-Gal-; components in italic being non-stoichiometric. The substitution rate of β-Galp units by GlcpA is 35%. Additionally, we determined that the glycolipid anchor of the LGMGal is based on an myo-inositol phosphoceramide composed of C₁₈-phytosphingosine and monohydroxylated lignoceric acid (2OHC_24:0 fatty acid).

The intrinsically disordered C-terminal F domain of the ecdysteroid receptor from Aedes aegypti exhibits metal ion-binding ability

The dominant vector of dengue and Zika diseases is a female Aedes aegypti mosquito. Its reproduction is controlled by the formation of an active heterodimer complex of the 20-hydroxyecdysone receptor (EcR) and Ultraspiracle protein (Usp). Although EcR exhibits a structural and functional organization typical of nuclear receptors (NRs), the EcR C-terminus has an additional F domain (AaFEcR) that is rarely present in the NRs superfamily. The presence of F domains is evolutionarily not well conserved in the NRs. The structure-function relationship of EcR F domains in arthropods is unclear and enigmatic. To date, there have been no data concerning the structure and function of AaFEcR. Our results showed that AaFEcR belongs to a family of intrinsically disordered proteins (IDPs) and possesses putative pre-molten globule (PMG) characteristics. Unexpectedly, additional amino acid composition in silico analyses revealed the presence of short unique repeated Pro-His clusters forming an HGPHPHPHG motif, which is similar to those responsible for Zn²⁺ and Cu²⁺ binding in histidine-proline-rich glycoproteins (HPRGs). Using SEC, SV-AUC and ESI-TOF MS, we showed that the intrinsically disordered AaFEcR is able to bind metal ions and form complexes with these ions. Our studies provide new insight into the structural organization and activities of the F domains of NRs. This unique for the F domains of NRs ion-binding propensity demonstrated by the AaFEcR domain may be a part of the ecdysteroid receptor's mechanism for regulating the expression of genes encoding oxidative stress-protecting proteins.

CRISPR/Cas9-mediated knockout of six glycosyltransferase genes in Nicotiana benthamiana for the production of recombinant proteins lacking β-1,2-xylose and core α-1,3-fucose

Plants offer fast, flexible and easily scalable alternative platforms for the production of pharmaceutical proteins, but differences between plant and mammalian N-linked glycans, including the presence of β-1,2-xylose and core α-1,3-fucose residues in plants, can affect the activity, potency and immunogenicity of plant-derived proteins. Nicotiana benthamiana is widely used for the transient expression of recombinant proteins so it is desirable to modify the endogenous N-glycosylation machinery to allow the synthesis of complex N-glycans lacking β-1,2-xylose and core α-1,3-fucose. Here, we used multiplex CRISPR/Cas9 genome editing to generate N. benthamiana production lines deficient in plant-specific α-1,3-fucosyltransferase and β-1,2-xylosyltransferase activity, reflecting the mutation of six different genes. We confirmed the functional gene knockouts by Sanger sequencing and mass spectrometry-based N-glycan analysis of endogenous proteins and the recombinant monoclonal antibody 2G12. Furthermore, we compared the CD64-binding affinity of 2G12 glycovariants produced in wild-type N. benthamiana, the newly generated FX-KO line, and Chinese hamster ovary (CHO) cells, confirming that the glyco-engineered antibody performed as well as its CHO-produced counterpart.

Two Heat Resistant Endopeptidases from Pseudomonas Species with Destabilizing Potential during Milk Storage

In the current study, the extracellular endopeptidases from Pseudomonas lundensis and Pseudomonas proteolytica were investigated. The amino acid sequence identity between both endopeptidases is 68%. Both endopeptidases were purified to homogeneity and partially characterized. They were classified as metallopeptidases with a maximum activity at pH 10.0 ( P. lundensis) or 8.5 ( P. proteolytica) at 35 °C. Both remained active in skim milk with 39.7 ± 2.4% and 24.5 ± 3.3%, respectively, of the initial enzyme activity after UHT processing (138 °C for 20 s), indicating the relevance for milk destabilization. The transition points in buffer were determined at 50 °C ( P. lundensis) and 43 °C ( P. proteolytica) using circular dichroism spectroscopy. The loss of the secondary structure at different temperatures was correlated with residual peptidase activities after heat treatment. The ability to destabilize UHT milk was proven by supplementation of skim milk with endopeptidase and storage for 4 weeks.

Regulation of erythrocyte Na+/K+/2Cl- cotransport by an oxygen-switched kinase cascade

Many erythrocyte processes and pathways, including glycolysis, the pentose phosphate pathway (PPP), KCl cotransport, ATP release, Na⁺/K⁺-ATPase activity, ankyrin-band 3 interactions, and nitric oxide (NO) release, are regulated by changes in O₂ pressure that occur as a red blood cell (RBC) transits between the lungs and tissues. The O₂ dependence of glycolysis, PPP, and ankyrin-band 3 interactions (affecting RBC rheology) are controlled by O₂-dependent competition between deoxyhemoglobin (deoxyHb), but not oxyhemoglobin (oxyHb), and other proteins for band 3. We undertook the present study to determine whether the O₂ dependence of Na⁺/K⁺/2Cl^- cotransport (catalyzed by Na⁺/K⁺/2Cl^- cotransporter 1 [NKCC1]) might similarly originate from competition between deoxyHb and a protein involved in NKCC1 regulation for a common binding site on band 3. Using three transgenic mouse strains having mutated deoxyhemoglobin-binding sites on band 3, we found that docking of deoxyhemoglobin at the N terminus of band 3 displaces the protein with no lysine kinase 1 (WNK1) from its overlapping binding site on band 3. This displacement enabled WNK1 to phosphorylate oxidative stress-responsive kinase 1 (OSR1), which, in turn, phosphorylated and activated NKCC1. Under normal solution conditions, the NKCC1 activation increased RBC volume and thereby induced changes in RBC rheology. Because the deoxyhemoglobin-mediated WNK1 displacement from band 3 in this O₂ regulation pathway may also occur in the regulation of other O₂-regulated ion transporters, we hypothesize that the NKCC1-mediated regulatory mechanism may represent a general pattern of O₂ modulation of ion transporters in erythrocytes.

Purification and characterization of alkaline protease with novel properties from Bacillus cereus strain S8

Proteases are the hydrolytic enzymes which hydrolyzes peptide bond between proteins with paramount applications in pharmaceutical and industrial sector. Therefore production of proteases with efficient characteristics of biotechnological interest from novel strain is significant. Hence, in this study, an alkaline serine protease produced by Bacillus cereus strain S8 (MTCC NO 11901) was purified and characterized. The alkaline protease was purified by ammonium sulfate precipitation (50%), ion exchange (DEAE-Cellulose) and gel filtration (Sephadex G-100) chromatographic techniques. As a result of this purification, a protein with specific activity of 300U/mg protein was obtained with purification fold 17.04 and recovery percentage of 34.6%. The molecular weight of the purified protease was determined using SDS-PAGE under non-reducing (71 kDa) and reducing conditions (35 kDa and 22 kDa). Zymogram analysis revealed that proteolytic activity was only associated with 22 kDa. These results indicate that existence of the enzyme as dimer in its native state. The molecular weight of the protease (22 kDa) was also determined by gel filtration (Sephadex G-200) chromatography and it was calculated as 21.8 kDa. The optimum activity of the protease was observed at pH 10.0 and temperature 70 °C with great stability towards pH and temperature with casein as a specific substrate. The enzyme was completely inhibited by PMSF and TLCK indicating that it is a serine protease of trypsin type. The enzyme exhibits a great stability towards organic solvents, oxidizing and bleaching agents and it is negatively influenced by Li2+ and Co2+ metal ions. The purified protein was further characterized by Matrix Assisted Laser Desorption Ionization/Mass Spectroscopy (MALDI/MS) analysis which reveals that total number of amino acids is 208 with isoelectric point 9.52.

Cloning, large-scale production and characterization of fusion protein (P-TUFT-ALT-2) of Brugian abundant larval transcript-2 with tuftsin in Pichia pastoris

Lymphatic filariasis is a "disease of poor people" due to a large section of affected people with economic backwardness. Therefore, successful elimination of this disease requires a cost-effective prophylactic agent such as vaccine along with conventional drugs. The Abundant Larval Transcript-2 (BmALT-2) protein of Brugia malayi has been recognized as the most potential vaccine candidate. Tuftsin, a tetra-peptide immunopotentiator has already shown the enhanced immunogenicity of various vaccine antigens in earlier studies. This study deals with the development of tuft-alt-2 fusion construct and a suitable culture condition for its large-scale production in Pichia pastoris. The recombinant P. pastoris/tuft-alt-2 with 9-11 copies of the gene construct exhibited the highest expression level. The molecular weight of P-TUFT-ALT-2 was determined as 28 kDa in SDS-PAGE including 3 kDa due to glycosylation. The dry cell biomass was 57.4 gL^-1 in the bioreactor. The P-TUFT-ALT-2 expression was measured as about 35 mg L^-1, which was 102% higher than flask culture. The P-TUFT-ALT-2 produced the highest 65,000 IgG peak titer in Balb/c mice. Moreover, P-TUFT-ALT-2 exhibited about 9.46% higher splenocyte proliferation than E. coli expressed E-ALT-2 alone. The enhanced secreted production of P-TUFT-ALT-2 in bioreactor would step up its commercialization as an inexpensive commercial vaccine for human lymphatic filariasis.

A practical toxicity bioassay for vicine and convicine levels in faba bean (Vicia faba)

BACKGROUND

Faba bean (Vicia faba) vicine and convicine (V-C) aglycones (divicine and isouramil respectively) provoke an acute hemolytic anemia called favism in individuals with a glucose-6-phosphate dehydrogenase (G6PD) enzyme defect in their red blood cells. Geneticists/plant breeders are working with faba bean to decrease V-C levels to improve public acceptance of this high-protein pulse crop. Here, we present a fast and simple ex vivo in vitro bioassay for V-C toxicity testing of faba bean or faba bean food products.

RESULTS

We have shown that 1,3-bis (2-chloroethyl)-1-nitrosourea (BCNU)-treated (i.e., sensitized) normal red blood cells, like G6PD-defective blood, displayed (i) continuous glutathione (GSH) depletion with no regeneration as incubation time and the dose of aglycones increased, (ii) progressive accumulation of denatured hemoglobin products into high molecular weight (HMW) proteins with increased aglycone dose, (iii) both band 3 membrane proteins and hemichromes, in HMW protein aggregates. We have also demonstrated that sensitized red blood cells can effectively differentiate various levels of toxicity among faba bean varieties through the two hemolysis biomarkers: GSH depletion and HMW clumping.

CONCLUSION

BCNU-sensitized red blood cells provide an ideal model for favism blood, to assess and compare the toxicity of faba bean varieties and their food products. © 2018 Society of Chemical Industry.

Intrinsically disordered N-terminal domain of the Helicoverpa armigera Ultraspiracle stabilizes the dimeric form via a scorpion-like structure

Nuclear receptors (NRs) are a family of ligand-dependent transcription factors activated by lipophilic compounds. NRs share a common structure comprising three domains: a variable N-terminal domain (NTD), a highly conserved globular DNA-binding domain and a ligand-binding domain. There are numerous papers describing the molecular details of the latter two globular domains. However, very little is known about the structure-function relationship of the NTD, especially as an intrinsically disordered fragment of NRs that may influence the molecular properties and, in turn, the function of globular domains. Here, we investigated whether and how an intrinsically disordered NTD consisting of 58 amino acid residues affects the functions of the globular domains of the Ultraspiracle protein from Helicoverpa armigera (HaUsp). The role of the NTD was examined for two well-known and easily testable NR functions, i.e., interactions with specific DNA sequences and dimerization. Electrophoretic mobility shift assays showed that the intrinsically disordered NTD influences the interaction of HaUsp with specific DNA sequences, apparently by destabilization of HaUsp-DNA complexes. On the other hand, multi-angle light scattering and sedimentation velocity analytical ultracentrifugation revealed that the NTD acts as a structural element that stabilizes HaUsp homodimers. Molecular models based on small-angle X-ray scattering indicate that the intrinsically disordered NTD may exert its effects on the tested HaUsp functions by forming an unexpected scorpion-like structure, in which the NTD bends towards the ligand-binding domain in each subunit of the HaUsp homodimer. This structure may be crucial for specific NTD-dependent regulation of the functions of globular domains in NRs.

Axonal sodium channel NaV1.2 drives granule cell dendritic GABA release and rapid odor discrimination

Dendrodendritic synaptic interactions between olfactory bulb mitral and granule cells represent a key neuronal mechanism of odor discrimination. Dendritic release of gamma-aminobutyric acid (GABA) from granule cells contributes to stimulus-dependent, rapid, and accurate odor discrimination, yet the physiological mechanisms governing this release and its behavioral relevance are unknown. Here, we show that granule cells express the voltage-gated sodium channel α-subunit Na_V1.2 in clusters distributed throughout the cell surface including dendritic spines. Deletion of Na_V1.2 in granule cells abolished spiking and GABA release as well as inhibition of synaptically connected mitral cells (MCs). As a consequence, mice required more time to discriminate highly similar odorant mixtures, while odor discrimination learning remained unaffected. In conclusion, we show that expression of Na_V1.2 in granule cells is crucial for physiological dendritic GABA release and rapid discrimination of similar odorants with high accuracy. Hence, our data indicate that neurotransmitter-releasing dendritic spines function just like axon terminals.

In axonal nerve terminals, neurotransmitter release is triggered by a localized Ca²⁺ nanodomain generated by voltage-gated calcium channels in response to an action potential, which in turn is mediated by voltage-gated sodium channels. Dendritic neurotransmitter release has been thought to work differently, mainly depending on Ca²⁺ entering directly through N-methyl-D-aspartate (NMDA) receptors, a subtype of ligand-gated ion channel. To further investigate how dendritic neurotransmitter is released, we studied granule cells in the olfactory bulb of mice, which establish inhibitory dendrodendritic synapses with mitral cells. We show that granule cells express voltage-gated sodium channels predominantly localized in dendrites and spines. Down-regulation of these channels precludes action potential firing in granule cells and strongly reduces mitral cell inhibition. Behaviorally, these mice require more time to discriminate highly similar odorants at maximal accuracy. Therefore, the inhibition of mitral cells relies on neurotransmitter released from the dendrites of granule cells by a mechanism that resembles axonal neurotransmitter release much more than previously thought.

Paper Adsorbents Remove Coomassie Blue from Gel Destain and Used Gel Stain in an Environment-Friendly Manner

Coomassie Brilliant Blue (CBB), used to stain protein gels, is known to be toxic. Therefore, laboratories do not discard used CBB into the sink owing to the possibility of it contaminating drinking water supplies. We tested the ability of various paper adsorbents to adsorb CBB released from gels during destaining. The efficiency was as follows-Kimwipes > Teri towels > multifold towels > Whatman numbers 1 and 3 filter papers. Addition of three Kimwipes during destaining helped adsorb the dye released from a CBB-stained mini-gel. Stain removal with Kimwipes helps reduce destain use, organic waste accumulation, enable recycling of nonradioactive destaining solution and is 7.5-fold cheaper than an available method for CBB disposal. Next, we used Kimwipes to deplete the dye from a used CBB staining solution awaiting proper disposal by our Institutional Safety Office. Seventy five Kimwipes successfully helped remove the dye from a 0.05% CBB staining solution in 5-10 min. The blue Kimwipes did not release the CBB stain even when squeezed dry after incubation in various salts, water, or acid solutions for 5 weeks. The CBB removed thus can be simply disposed of as solid waste and will not leach out from solid landfills. Kimwipes, thus, enables CBB disposal in an environmentally friendly manner and allows for recycling of destaining solution.

Carriers, exchangers, and cotransporters in the first 100 years of the Journal of General Physiology

Jennings reviews the many contributions of JGP articles to our current understanding of solute transporter mechanisms.

Transporters, pumps, and channels are proteins that catalyze the movement of solutes across membranes. The single-solute carriers, coupled exchangers, and coupled cotransporters that are collectively known as transporters are distinct from conductive ion channels, water channels, and ATP-hydrolyzing pumps. The main conceptual framework for studying transporter mechanisms is the alternating access model, which comprises substrate binding and release events on each side of the permeability barrier and translocation events involving conformational changes between inward-facing and outward-facing conformational states. In 1948, the Journal of General Physiology began to publish work that focused on the erythrocyte glucose transporter—the first transporter to be characterized kinetically—followed by articles on the rates, stoichiometries, asymmetries, voltage dependences, and regulation of coupled exchangers and cotransporters beginning in the 1960s. After the dawn of cDNA cloning and sequencing in the 1980s, heterologous expression systems and site-directed mutagenesis allowed identification of the functional roles of specific amino acid residues. In the past two decades, structures of transport proteins have made it possible to propose specific models for transporter function at the molecular level. Here, we review the contribution of JGP articles to our current understanding of solute transporter mechanisms. Whether the topic has been kinetics, energetics, regulation, mutagenesis, or structure-based modeling, a common feature of these articles has been a quantitative, mechanistic approach, leading to lasting insights into the functions of transporters.

Use of Laser Assisted Optical Rotational Cell Analyzer (LoRRca MaxSis) in the Diagnosis of RBC Membrane Disorders, Enzyme Defects, and Congenital Dyserythropoietic Anemias: A Monocentric Study on 202 Patients

Chronic hemolytic anemias are a group of heterogeneous diseases mainly due to abnormalities of red cell (RBC) membrane and metabolism. The more common RBC membrane disorders, classified on the basis of blood smear morphology, are hereditary spherocytosis (HS), elliptocytosis, and hereditary stomatocytoses (HSt). Among RBC enzymopathies, the most frequent is pyruvate kinase (PK) deficiency, followed by glucose-6-phosphate isomerase, pyrimidine 5′ nucleotidase P5′N, and other rare enzymes defects. Because of the rarity and heterogeneity of these diseases, diagnosis may be often challenging despite the availability of a variety of laboratory tests. The ektacytometer laser-assisted optical rotational cell analyser (LoRRca MaxSis), able to assess the RBC deformability in osmotic gradient conditions (Osmoscan analysis), is a useful diagnostic tool for RBC membrane disorders and in particular for the identification of hereditary stomatocytosis. Few data are so far available in other hemolytic anemias. We evaluated the diagnostic power of LoRRca MaxSis in a large series of 140 patients affected by RBC membrane disorders, 37 by enzymopathies, and 16 by congenital diserythropoietic anemia type II. Moreover, nine patients with paroxysmal nocturnal hemoglobinuria (PNH) were also investigated. All the hereditary spherocytoses, regardless the biochemical defect, showed altered Osmoscan curves, with a decreased Elongation Index (EI) max and right shifted Omin; hereditary elliptocytosis (HE) displayed a trapezoidal curve and decreased EImax. Dehydrated hereditary stomatocytosis (DHSt) caused by PIEZO1 mutations was characterized by left-shifted curve, whereas KCNN4 mutations were associated with a normal curve. Congenital diserythropoietic anemia type II and RBC enzymopathies had Osmoscan curve within the normal range except for glucosephosphate isomerase (GPI) deficient cases who displayed an enlarged curve associated with significantly increased Ohyper, offering a new diagnostic tool for this rare enzyme defect. The Osmoscan analysis performed by LoRRca MaxSis represents a useful and feasible first step screening test for specialized centers involved in the diagnosis of hemolytic anemias. However, the results should be interpreted by caution because different factors (i.e., splenectomy or coexistent diseases) may interfere with the analysis; additional tests or molecular investigations are therefore needed to confirm the diagnosis.

Detection of the 170 kDa P-Glycoprotein in Neoplastic and Normal Tissues

A membrane purification procedure and an immunoblotting assay have been designed to allow screening of human solid tumors for overexpression of the GP170 glycoprotein without employing a disaggregation method to obtain cell suspensions. The electrophoresed membrane proteins were probed, after Western Blotting, with the C219 monoclonal antibody and iodinated Protein A. The labeling intensity of the bands on the autoradioimmunoblots were quantified by densitometry. To test for the presence of GP170, we used membranes from the UV 2237 fibrosarcoma line and its adriamycin-resistant variant ADMR, grown in vitro or as solid tumor in mice. Membranes of human normal and tumor tissues obtained from previously untreated patients were also tested. An immunoreaction was observed in the adriamycin-resistant UV 2237 lines grown in vitro or in vivo. Quantitatively, the binding of the resistant cell line grown in vitro was higher than that observed in cells grown in mice. Bands in the GP 170 region were observed in 4/7 normal and in 7/7 tumor colon tissues and in the normal medulla from 2 patients with cancer of the renal cortex. No reaction could be found in samples from normal tissue, primary tumor or nodal metastasis from 7 patients with breast cancer.

Molecular Characterization of Cellular Proteins from Colorectal Tumors

Aims and background

Recent evidence has suggested that progressive stages of colorectal tumorigenesis can be defined by a sequence of genetic events characterized by altered expression of certain genes and the appearance of cancer-specific proteins. Although the significance of these events is still not clear, expression of cancer-specific protein components may be directly involved in the neoplastic transformation. The purpose of the present study was to compare molecular characteristics of cellular proteins from human colorectal tumors and normal colonic mucosa.

Methods

Normal mucosa and colorectal tumors from 18 patients were fractionated by a differential centrifugation scheme into four cellular fractions, i.e., nuclear, mitochondrial (10P), microsomal (100P) and cytosolic (100S). The proteins of these fractions from normal and tumorigenic mucosa were analyzed by one-dimensional polyacrylamide gel electrophoresis followed by Coomassie brilliant blue R-250 and silver nitrate staining. Nuclear proteins from normal and neoplastic tissues which had revealed the most significant diversities were further characterized by two-dimensional gel electrophoresis. Electrophoretically cancer-specific nuclear proteins in the molecular mass zone 35-40 kDa were used as immunogen to produce rabbit polyclonal antibodies.

Results

Electrophoretic analysis by one-dimensional gel electrophoresis showed clear differences in molecular characteristics of cellular proteins between normal and tumorigenic mucosa, especially among nuclear fractions. The latter were also confirmed by their two-dimensional electrophoresis results. Rabbit antibodies raised against electrophoretically specific nuclear proteins characterized by molecular mass of 35-40 kDa cross-reacted with 36 kDa polypeptide in 15 of 18 (83.3%) studied nuclear fractions of colorectal tumors but not with any normal mucosa. In some cases, nuclear cancer-associated components of 38 and 40 kDa were also recognized by these antibodies.

Conclusions

During colorectal carcinogenesis, specific expression of several nuclear proteins takes place. One of them, the polypeptide of 36 kDa not found in normal colonic epithelium, was shared by over 83% of the studied carcinomas despite variations in detailed cancer properties. This particular nuclear protein may be considered as a potential marker for the colon malignancy.

Rapid Electrophoretic Staining and Destaining of Polyacrylamide Gels

Coomassie brilliant blue (CBB) dyes have been commonly used for the staining of protein bands in polyacrylamide gel electrophoresis (PAGE) gels. However, the staining and destaining of CBB dyes are time-consuming, and the use of methanol is hazardous to one's health. I introduce a rapid electrophoretic destaining method using a semi-dry transfer unit and a high current power supply. In this method, ethanol was used instead of the hazardous methanol. Most of the protein bands became visible in 30 min. After a secondary destaining step, residual CBB was completely destained. The detection limit for a tested protein (5 ng) was higher than that of the conventional method. Therefore, this method is superior in its speed, safety, low cost, and sensitivity.

Novel compound heterozygous SPTA1 mutations in a patient with hereditary elliptocytosis

Hereditaryelliptocytosis (HE) is a hereditary hemolytic disease, characterized by the presence of many elliptical erythrocytes in the peripheral blood that is caused by abnormal cytoskeletal proteins in the erythrocyte membrane. In the present study, a novel, causal HE mutation was reported. Routine blood examinations were performed on the proband and their family, and the fluorescence intensity of eosin‑5‑maleimide (EMA)‑labeled erythrocytes was determined via flow cytometry. Subsequently, DNA was extracted from the peripheral blood of the proband and their family members, and amplified by quantitative polymerase chain reaction. The Sanger sequencing approach was used to determine and identify gene mutations, which were verified by matrix‑assisted laser desorption‑ionization time of flight (MALDI‑TOF) mass spectrometry. To exclude genetic polymorphisms, newly identified mutations were subjected to large‑scale gene screening using high‑resolution melt analysis. Protein expression levels in the erythrocyte membrane of the proband were determined via SDS‑PAGE, which demonstrated that, compared with healthy controls, the proband exhibited a reduction in EMA‑labeled erythrocytes. In addition, DNA analysis demonstrated that the proband carried three mutations in the spectrin α chain erythrocytic 1 (SPTA1) gene: c.161A>C, c.5572C>G and 6531‑12C>T. The corresponding mutant polypeptides were also analyzed by MALDI‑TOF mass spectroscopy. SDS‑PAGE analysis indicated that the proband exhibited normal levels of erythrocyte membrane proteins. In the present study, a novel HE case with a His54Pro mutation in the SPTA1 gene was reported. The results suggested that the His54Pro mutation influenced the role of erythrocyte membrane proteins without reducing its level of expression.

A natural variant of arylsulfatase from Kluyveromyces lactis shows no formylglycine modification and has no enzyme activity

Kluyveromyces lactis is a common fungal microorganism used for the production of enzyme preparations such as β-galactosidases (native) or chymosin (recombinant). It is generally important that enzyme preparations have no unwanted side activities. In the case of β-galactosidase preparations produced from K. lactis, an unwanted side activity could be the presence of arylsulfatase (EC 3.1.6.1). Due to the action of arylsulfatase, an unpleasant "cowshed-like" off-flavor would occur in the final product. The best choice to avoid this is to use a yeast strain without this activity. Interestingly, we found that certain natural K. lactis strains express arylsulfatases, which only differ in one amino acid at position 139. The result of this difference is that K. lactis DSM 70799 (expressing R139 variant) shows no arylsulfatase activity, unlike K. lactis GG799 (expressing S139 variant). After recombinant production of both variants in Escherichia coli, the R139 variant remains inactive, whereas the S139 variant showed full activity. Mass spectrometric analyses showed that the important posttranslational modification of C56 to formylglycine was not found in the R139 variant. By contrast, the C56 residue of the S139 variant was modified. We further investigated the packing and secondary structure of the arylsulfatase variants using optical spectroscopy, including fluorescence and circular dichroism. We found out that the inactive R139 variant exhibits a different structure regarding folding and packing compared to the active S139 variant. The importance of the amino acid residue 139 was documented further by the construction of 18 more variants, whereof only ten showed activity but always reduced compared to the native S139 variant.

Flow rate dependent continuous hydrolysis of protein isolates

Food protein hydrolysates are often produced in unspecific industrial batch processes. The hydrolysates composition underlies process-related fluctuations and therefore the obtained peptide fingerprint and bioactive properties may vary. To overcome this obstacle and enable the production of specific hydrolysates with selected peptides, a ceramic capillary system was developed and characterized for the continuous production of a consistent peptide composition. Therefore, the protease Alcalase was immobilized on the surface of aminosilane modified yttria stabilized zirconia capillaries with a pore size of 1.5 µm. The loading capacity was 0.3 µg enzyme per mg of capillary with a residual enzyme activity of 43%. The enzyme specific peptide fingerprint produced with this proteolytic capillary reactor system correlated with the degree of hydrolysis, which can be controlled over the residence time by adjusting the flow rate. Common food proteins like casein, sunflower and lupin protein isolates were tested for continuous hydrolysis in the developed reactor system. The peptide formation was investigated by high-performance liquid chromatography. Various trends were found for the occurrence of specific peptides. Some are just intermediately occurring, while others cumulate by time. Thus, the developed continuous reactor system enables the production of specific peptides with desired bioactive properties.

Molecular mechanism for the red blood cell senescence clock

Lacking protein synthesis machinery and organelles necessary for autophagy or apoptosis, aged red blood cells (RBCs) are marked by circulating auto-antibodies for macrophage-mediated clearance. The antigen recognized by these auto-antibodies is the major protein of the RBC membrane, Band 3. To ensure regulation and specificity in clearance, the molecular "clock" must mark senescent cells in a way that differentiates them from younger cells, to prevent premature clearance. Predominant models of Band 3 senescence signaling are reviewed, and merits are discussed in light of the recently published crystal structure of the Band 3 membrane domain. © 2017 IUBMB Life, 70(1):32-40, 2018.

A Comprehensive Review of Our Current Understanding of Red Blood Cell (RBC) Glycoproteins

Human red blood cells (RBC), which are the cells most commonly used in the study of biological membranes, have some glycoproteins in their cell membrane. These membrane proteins are band 3 and glycophorins A-D, and some substoichiometric glycoproteins (e.g., CD44, CD47, Lu, Kell, Duffy). The oligosaccharide that band 3 contains has one N-linked oligosaccharide, and glycophorins possess mostly O-linked oligosaccharides. The end of the O-linked oligosaccharide is linked to sialic acid. In humans, this sialic acid is N-acetylneuraminic acid (NeuAc). Another sialic acid, N-glycolylneuraminic acid (NeuGc) is present in red blood cells of non-human origin. While the biological function of band 3 is well known as an anion exchanger, it has been suggested that the oligosaccharide of band 3 does not affect the anion transport function. Although band 3 has been studied in detail, the physiological functions of glycophorins remain unclear. This review mainly describes the sialo-oligosaccharide structures of band 3 and glycophorins, followed by a discussion of the physiological functions that have been reported in the literature to date. Moreover, other glycoproteins in red blood cell membranes of non-human origin are described, and the physiological function of glycophorin in carp red blood cell membranes is discussed with respect to its bacteriostatic activity.

A simple, time-saving, microwave-assisted periodic acid-Schiff´s staining of glycoproteins on 1D electrophoretic gels

We introduce an optimized periodic acid-Schiff´s staining of glycoproteins on 1D electrophoretic gels. Thanks to heating in a household microwave oven the protocol of standard periodic acid-Schiff´s staining has been accelerated from 6 h to below 10 min employing standard chemistry. At the same time, we show that the microwave-assisted glycoprotein staining is at least as sensitive as the conventional approach. All glycoproteins stained by the microwave-accelerated procedure were successfully identified using MALDI TOF/TOF mass spectrometry. The ensuing reduction in gel staining time and simplification of the staining protocol should significantly increase laboratory throughput when glycoprotein detection on electrophoretic gels is required in large numbers.

Aging Does Not Affect Axon Initial Segment Structure and Somatic Localization of Tau Protein in Hippocampal Neurons of Fischer 344 Rats

Little is known about the specific contributions of aging to the neuron dysfunction and death in Alzheimer’s disease (AD). AD is characterized by the pathological accumulation of abnormal tau (a microtubule-associated protein), and the mislocalization of tau from the axon to the somatodendritic compartment is thought to play an important role in disease pathogenesis. The axon initial segment (AIS) is thought to play a role in the selective localization of tau in the axonal compartment. Thus, disruption in the AIS barrier may allow tau to diffuse freely back into the somatodendritic compartment and potentially lead to neurotoxicity. Here, we analyzed AISs using stereological methods and protein immunoblotting, and the localization of tau was assessed with immunofluorescence optical density measurements and protein immunoblotting. None of the outcome measurements assessed, including AIS structure, AIS protein levels, the distribution of tau in neurons of the hippocampus (HP), and total tau or phospho-tau protein levels were different in young, middle-, and old-age Fischer 344 rats. The outcome measurements assessed, including AIS structure, AIS protein levels, the distribution of tau in neurons of the HP, and total tau or phospho-tau protein levels were not different in young, middle-, and old-age Fischer 344 rats, with the exception of a small reduction in AIS volume and diameter in the CA2 region of aged animals. These data suggest that aging largely has no effect on these properties of the AIS or tau distribution, and thus, may not contribute directly to tau mislocalization.

Circulating primitive erythroblasts establish a functional, protein 4.1R-dependent cytoskeletal network prior to enucleating

Hematopoietic ontogeny is characterized by distinct primitive and definitive erythroid lineages. Definitive erythroblasts mature and enucleate extravascularly and form a unique membrane skeleton, composed of spectrin, 4.1R-complex, and ankyrinR-complex components, to survive the vicissitudes of the adult circulation. However, little is known about the formation and composition of the membrane skeleton in primitive erythroblasts, which progressively mature while circulating in the embryonic bloodstream. We found that primary primitive erythroblasts express the major membrane skeleton genes present in similarly staged definitive erythroblasts, suggesting that the composition and formation of this membrane network is conserved in maturing primitive and definitive erythroblasts despite their respective intravascular and extravascular locations. Membrane deformability and stability of primitive erythroblasts, assayed by microfluidic studies and fluorescence imaged microdeformation, respectively, significantly increase prior to enucleation. These functional changes coincide with protein 4.1 R isoform switching and protein 4.1R-null primitive erythroblasts fail to establish normal membrane stability and deformability. We conclude that maturing primitive erythroblasts initially navigate the embryonic vasculature prior to establishing a deformable cytoskeleton, which is ultimately formed prior to enucleation. Formation of an erythroid-specific, protein 4.1R-dependent membrane skeleton is an important feature not only of definitive, but also of primitive, erythropoiesis in mammals.

Nuances of electrophoresis study of titin/connectin

Almost 40 years has passed since the discovery of giant elastic protein titin (also known as connectin) of striated and smooth muscles using gel electrophoresis. Sodium dodecyl sulfate polyacrylamide gel electrophoresis is a major technique for studying the isoform composition and content of titin. This review provides historical insights into the technical aspects of the electrophoresis methods used to identify titin and its isoforms. We particularly focus on the nuances of the technique that improve the preservation of its primary structure so that its high molecular weight isoforms can be visualized.

'Gardos Channelopathy': a variant of hereditary Stomatocytosis with complex molecular regulation

The Gardos channel is a Ca²⁺ sensitive, K⁺ selective channel present in several tissues including RBCs, where it is involved in cell volume regulation. Recently, mutations at two different aminoacid residues in KCNN4 have been reported in patients with hereditary xerocytosis. We identified by whole exome sequencing a new family with two members affected by chronic hemolytic anemia carrying mutation R352H in the KCNN4 gene. No additional mutations in genes encoding for RBCs cytoskeletal, membrane or channel proteins were detected. We performed functional studies on patients’ RBCs to evaluate the effects of R352H mutation on the cellular properties and eventually on the clinical phenotype. Gardos channel hyperactivation was demonstrated in circulating erythrocytes and erythroblasts differentiated ex-vivo from peripheral CD34+ cells. Pathological alterations in the function of multiple ion transport systems were observed, suggesting the presence of compensatory effects ultimately preventing cellular dehydration in patient’s RBCs; moreover, flow cytometry and confocal fluorescence live-cell imaging showed Ca²⁺ overload in the RBCs of both patients and hypersensitivity of Ca²⁺ uptake by RBCs to swelling. Altogether these findings suggest that the ‘Gardos channelopathy’ is a complex pathology, to some extent different from the common hereditary xerocytosis.

Protective effect of Scutellaria species on AAPH-induced oxidative damage in human erythrocyte

BACKGROUND

Scutellaria baicalensis is a well-known plant in traditional Chinese medicine. Recently, several Scutellaria species with therapeutic potential have been recognized worldwide. Scutellaria colebrookiana and Scutellaria violacea, native to the Western Ghats of India, are reported to possess free radical scavenging efficacy. At present, the protective effect of these Scutellaria spp. against 2,2' azobis (2-amidinopropane) hydrochloride (AAPH)-induced oxidative damage in human erythrocytes has been analyzed.

METHODS

Oxidative stress in erythrocyte was induced by AAPH. The inhibition of hemolysis, membrane lipid peroxidation, and protein damage by chloroform extracts of Scutellaria spp. was assessed biochemically. Phytochemicals of the extracts were analyzed by Fourier transform infrared spectrophotometer (FTIR).

RESULTS

Approximately 95% of erythrocytes were lysed by AAPH over 3 h of incubation. Significant reduction in hemolysis was observed by the extracts, and the IC50 values were 18.3 and 23.5 μg/mL for S. colebrookiana and S. violacea, respectively. Both the extracts were found to inhibit AAPH-induced lipid peroxidation in ghost membrane with IC50 92±2.8 and 70±5.6 μg/mL. In the analysis of the membrane proteins using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), the AAPH-induced degradation of actin was found reduced by both the extracts. The FTIR spectrum revealed the presence of polyphenols, carboxylic acids, alkanes, and aromatic compounds in extracts. In quantitative analysis, the total polyphenolic content estimated was 380±0.23 and 203.7±1.4 mg of gallic acid equivalent per gram extract of S. colebrookiana and S. violacea.

CONCLUSIONS

Results indicate that S. colebrookiana and S. violacea are capable of protecting erythrocytes from oxidative damage. This cytoprotective effect of the extract is possibly by its antioxidant property.