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Haemoglobin A2 estimations by starch block electrophoresis

VELLA F

Med J Malaya, 1959 Sep;14:31-5.
PMID: 13855207
Matched MeSH terms: Hemoglobins/chemistry*
Fulltext Polyphenols in Barringtonia racemosa and their protection against oxidation of LDL, serum and haemoglobin

Kong KW, Mat-Junit S, Ismail A, Aminudin N, Abdul-Aziz A

Food Chem, 2014 Mar 1;146:85-93.
PMID: 24176317 DOI: 10.1016/j.foodchem.2013.09.012

The polyphenolic profiles and antioxidant activities of the water extracts of Barringtonia racemosa shoots (leaves and stems) were explored. Two methods, freeze drying and air drying, for preparation of the shoots, were also compared. Freeze drying was better as air drying caused 5-41% reduction of polyphenols. Three phenolic acids and three flavonoids were identified, using UHPLC. The descending order of polyphenols in the leaves and stems was gallic acid>ellagic acid>quercetin>protocatechuic acid>rutin>kaempferol. In vitro antioxidant analyses were performed using biological samples. In the LDL oxidation assay, B. racemosa leaf extract (IC50=73.0μg/ml) was better than stem extract (IC50=226μg/ml) at inhibiting the formation of TBARS and lipid hydroperoxides. Similar trends were observed for serum and haemoglobin oxidation. B. racemosa leaf extract was better than its stem extract in delaying the time required to oxidise haemoglobin to methaemoglobin. The high polyphenolic content of B. racemosa shoots could have contributed towards their antioxidative effects.

Matched MeSH terms: Hemoglobins/chemistry*
Carbonyl Functionalized Single-Walled Carbon Nanotube-Hb Crosslinked Network: A Novel Platform for Studying Bio-Electrochemistry and Electrocatalysis of Hemoglobin

Kafi AKM, Yam CCL, Azmi NS, Yusoff MM

J Nanosci Nanotechnol, 2018 Apr 01;18(4):2422-2428.
PMID: 29442911 DOI: 10.1166/jnn.2018.14327

In this work, the direct electrochemistry of hemoglobin (Hb), which was immobilized on carbonyl functionalized single walled carbon nanotube (SWCNT) and deposited onto a gold (Au) electrode has been described. The synthesis of the network of crosslinked SWCNT/Hb was done with the help of crosslinking agent EDC (1-ethyl-3-(3-dimethylaminopropyl) carbodiimide). The UV-Vis and FTIR spectroscopy of SWCNT/Hb networks showed that Hb maintained its natural structure and kept good stability. In addition with this, scanning electron microscopy (SEM) illustrated that SWCNT/Hb networks had a featured layered structure and Hb being strongly liked with SWCNT surface. Cyclic voltammetry (CV) was used to study and to optimize the performance of the resulting modified electrode. The cyclic voltammetric (CV) responses of SWCNT/Hb networks in pH 7.0 exhibit prominent redox couple for the FeIII/II redox process with a midpoint potential of -0.46 V and -0.34, cathodic and anodic respectively. Furthermore, SWCNT/Hb networks are utilized for the detection of hydrogen peroxide (H2O2). Electrochemical measurements reveal that the resulting SWCNT/Hb electrodes display high electrocatalytic activity to H2O2 with high sensitivity, wide linear range, and low detection limit. Overall, the electrochemical results are due to excellent biocompatibility and excellent electron transport efficiency of CNT as well as high Hb loading and synergistic catalytic effect of the modified electrode toward H2O2.

Matched MeSH terms: Hemoglobins/chemistry*
Estimating the refractive index of oxygenated and deoxygenated hemoglobin using genetic algorithm - support vector regression model

Alade IO, Bagudu A, Oyehan TA, Rahman MAA, Saleh TA, Olatunji SO

Comput Methods Programs Biomed, 2018 Sep;163:135-142.
PMID: 30119848 DOI: 10.1016/j.cmpb.2018.05.029

BACKGROUND AND OBJECTIVES: The refractive index of hemoglobin plays important role in hematology due to its strong correlation with the pathophysiology of different diseases. Measurement of the real part of the refractive index remains a challenge due to strong absorption of the hemoglobin especially at relevant high physiological concentrations. So far, only a few studies on direct measurement of refractive index have been reported and there are no firm agreements on the reported values of refractive index of hemoglobin due to measurement artifacts. In addition, it is time consuming, laborious and expensive to perform several experiments to obtain the refractive index of hemoglobin. In this work, we proposed a very rapid and accurate computational intelligent approach using Genetic Algorithm/Support Vector Regression models to estimate the real part of the refractive index for oxygenated and deoxygenated hemoglobin samples.
METHODS: These models utilized experimental data of wavelengths and hemoglobin concentrations in building highly accurate Genetic Algorithm/Support Vector Regression model (GA-SVR).
RESULTS: The developed methodology showed high accuracy as indicated by the low root mean square error values of 4.65 × 10-4 and 4.62 × 10-4 for oxygenated and deoxygenated hemoglobin, respectively. In addition, the models exhibited 99.85 and 99.84% correlation coefficients (r) for the oxygenated and deoxygenated hemoglobin, thus, validating the strong agreement between the predicted and the experimental results CONCLUSIONS: Due to the accuracy and relative simplicity of the proposed models, we envisage that these models would serve as important references for future studies on optical properties of blood.

Matched MeSH terms: Hemoglobins/chemistry*
Fulltext Hell's Gate globin I: an acid and thermostable bacterial hemoglobin resembling mammalian neuroglobin

Teh AH, Saito JA, Baharuddin A, Tuckerman JR, Newhouse JS, Kanbe M, et al.

FEBS Lett., 2011 Oct 20;585(20):3250-8.
PMID: 21925500 DOI: 10.1016/j.febslet.2011.09.002

Hell's Gate globin I (HGbI), a heme-containing protein structurally homologous to mammalian neuroglobins, has been identified from an acidophilic and thermophilic obligate methanotroph, Methylacidiphilum infernorum. HGbI has very high affinity for O(2) and shows barely detectable autoxidation in the pH range of 5.2-8.6 and temperature range of 25-50°C. Examination of the heme pocket by X-ray crystallography and molecular dynamics showed that conformational movements of Tyr29(B10) and Gln50(E7), as well as structural flexibility of the GH loop and H-helix, may play a role in modulating its ligand binding behavior. Bacterial HGbI's unique resistance to the sort of extreme acidity that would extract heme from any other hemoglobin makes it an ideal candidate for comparative structure-function studies of the expanding globin superfamily.

Matched MeSH terms: Hemoglobins/chemistry*
Enhanced direct electron transfer of redox protein based on multiporous SnO2 nanofiber-carbon nanotube nanocomposite and its application in biosensing

Alim S, Kafi AKM, Jose R, Yusoff MM, Vejayan J

Int J Biol Macromol, 2018 Jul 15;114:1071-1076.
PMID: 29625222 DOI: 10.1016/j.ijbiomac.2018.03.184

A novel third generation H2O2 biosensor is fabricated using multiporous SnO2 nanofiber/carbon nanotubes (CNTs) composite as a matrix for the immobilization of redox protein onto glassy carbon electrode. The multiporous nanofiber (MPNFs) of SnO2 is synthesized by electrospinning technique from the tin precursor. This nanofiber shows high surface area and good electrical conductivity. The SnO2 nanofiber/CNT composite increases the efficiency of biomolecule loading due to its high surface area. The morphology of the nanofiber has been evaluated by scanning electron microscopy (SEM). Cyclic Voltammetry and amperometry technique are employed to study and optimize the performance of the fabricated electrode. A direct electron transfer between the protein's redox centre and the glassy carbon electrode is established after fabrication of the electrode. The fabricated electrode shows excellent electrocatalytic reduction to H2O2. The catalysis currents increases linearly to the H2O2 concentration in a wide range of 1.0 10-6-1.4×10-4M and the lowest detection limit was 30nM (S/N=3). Moreover, the biosensor showed a rapid response to H2O2, a good stability and reproducibility.

Matched MeSH terms: Hemoglobins/chemistry*
Crystal structure of truncated haemoglobin from an extremely thermophilic and acidophilic bacterium

Jamil F, Teh AH, Schadich E, Saito JA, Najimudin N, Alam M

J. Biochem., 2014 Aug;156(2):97-106.
PMID: 24733432 DOI: 10.1093/jb/mvu023

A truncated haemoglobin (tHb) has been identified in an acidophilic and thermophilic methanotroph Methylacidiphilium infernorum. Hell's Gate Globin IV (HGbIV) and its related tHbs differ from all other bacterial tHbs due to their distinctively large sequence and polar distal haem pocket residues. Here we report the crystal structure of HGbIV determined at 1.96 Å resolution. The HGbIV structure has the distinctive 2/2 α-helical structure with extensions at both termini. It has a large distal site cavity in the haem pocket surrounded by four polar residues: His70(B9), His71(B10), Ser97(E11) and Trp137(G8). This cavity can bind bulky ligands such as a phosphate ion. Conformational shifts of His71(B10), Leu90(E4) and Leu93(E7) can also provide more space to accommodate larger ligands than the phosphate ion. The entrance/exit of such bulky ligands might be facilitated by positional flexibility in the CD1 loop, E helix and haem-propionate A. Therefore, the large cavity in HGbIV with polar His70(B9) and His71(B10), in contrast to the distal sites of other bacterial tHbs surrounded by non-polar residues, suggests its distinct physiological functions.

Matched MeSH terms: Hemoglobins/chemistry*
Fulltext Antioxidant capacities of peel, pulp, and seed fractions of Canarium odontophyllum Miq. fruit

Prasad KN, Chew LY, Khoo HE, Kong KW, Azlan A, Ismail A

J Biomed Biotechnol, 2010;2010.
PMID: 20936182 DOI: 10.1155/2010/871379

Antioxidant capacities of ethylacetate, butanol, and water fractions of peel, pulp, and seeds of Canarium odontophyllum Miq. (CO) were determined using various in vitro antioxidant models. Ethylacetate fraction of peel (EAFPE) exhibited the highest total phenolic (TPC), total flavonoid content (TFC), and antioxidant activities compared to pulp, seeds, and other solvent fractions. Antioxidant capacities were assayed by total antioxidant capability, 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical activity, ferric reducing antioxidant power (FRAP), and hemoglobin oxidation assay. Total phenolic content of ethylacetate fractions was positively correlated with the antioxidant activity. This is the first report on the antioxidant activities from CO fruit fractions. Thus, EAFPE can be used potentially as a readily accessible source of natural antioxidants and as a possible pharmaceutical supplement.

Matched MeSH terms: Hemoglobins/chemistry
Fulltext Acrylamide and Glycidamide Hemoglobin Adducts and Epithelial Ovarian Cancer: A Nested Case-Control Study in Nonsmoking Postmenopausal Women from the EPIC Cohort

Obón-Santacana M, Lujan-Barroso L, Travis RC, Freisling H, Ferrari P, Severi G, et al.

Cancer Epidemiol Biomarkers Prev, 2016 Jan;25(1):127-34.
PMID: 26598536 DOI: 10.1158/1055-9965.EPI-15-0822

BACKGROUND: Acrylamide was classified as "probably carcinogenic to humans (group 2A)" by the International Agency for Research on Cancer. Epithelial ovarian cancer (EOC) is the fourth cause of cancer mortality in women. Five epidemiological studies have evaluated the association between EOC risk and dietary acrylamide intake assessed using food frequency questionnaires, and one nested case-control study evaluated hemoglobin adducts of acrylamide (HbAA) and its metabolite glycidamide (HbGA) and EOC risk; the results of these studies were inconsistent.
METHODS: A nested case-control study in nonsmoking postmenopausal women (334 cases, 417 controls) was conducted within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Unconditional logistic regression models were used to estimate ORs and 95% confidence intervals (CI) for the association between HbAA, HbGA, HbAA+HbGA, and HbGA/HbAA and EOC and invasive serous EOC risk.
RESULTS: No overall associations were observed between biomarkers of acrylamide exposure analyzed in quintiles and EOC risk; however, positive associations were observed between some middle quintiles of HbGA and HbAA+HbGA. Elevated but nonstatistically significant ORs for serous EOC were observed for HbGA and HbAA+HbGA (ORQ5vsQ1, 1.91; 95% CI, 0.96-3.81 and ORQ5vsQ1, 1.90; 95% CI, 0.94-3.83, respectively); however, no linear dose-response trends were observed.
CONCLUSION: This EPIC nested case-control study failed to observe a clear association between biomarkers of acrylamide exposure and the risk of EOC or invasive serous EOC.
IMPACT: It is unlikely that dietary acrylamide exposure increases ovarian cancer risk; however, additional studies with larger sample size should be performed to exclude any possible association with EOC risk.

Matched MeSH terms: Hemoglobins/chemistry