scholarly journals Chemical properties of the N-termini of human haemoglobin

1982 ◽  
Vol 203 (2) ◽  
pp. 435-443 ◽  
Author(s):  
H Kaplan ◽  
P A Hamel ◽  
A M L Chan ◽  
G Oda
Keyword(s):  
Acetic Anhydride ◽  
Conformational Change ◽  
Chemical Properties ◽  
High Reactivity ◽  
Alkaline Ph ◽  
Amino Groups ◽  
Human Haemoglobin ◽  
Ph Values ◽  
Ph Dependent ◽  
Alkaline Bohr Effect

The chemical properties, namely pK and reactivity, of the N-termini of oxyhaemoglobin and deoxyhaemoglobin toward acetic anhydride and 1-fluoro-2,4-dinitrobenzene (Dnp-F) were determined by the competitive-labelling approach [Kaplan, Stevenson & Hartley, (1971) Biochem. J. 124, 289-229; Duggleby & Kaplan (1975) Biochemistry 14, 5168-5175]. At physiological pH and temperature, the valine-1 alpha and valine-1-beta amino groups had unusually low pK values, but showed only minimal changes in their pK values on deoxygenation. Between pH 7.5 and pH 8.0 a deviation was observed in the pH-reactivity profiles and the apparent pK values became markedly pH-dependent. It was found that Dnp-F, but not acetic anhydride, had an abnormally high reactivity toward the N-termini. It is concluded that the valine-1 alpha and valine-1 beta N-termini make little or no contribution to the alkaline Bohr effect at physiological pH values. The high reactivity toward Dnp-F is attributed to an interaction or binding near the N-terminal region, and the discontinuity in the pH-reactivity profile at moderate alkaline pH values to a conformational change which alters the environment of these groups.

scholarly journals Identification of histidine-122α in human haemoglobin as one of the unknown alkaline Bohr groups by hydrogen-tritium exchange

1978 ◽  
Vol 173 (2) ◽  
pp. 651-657 ◽  
Author(s):  
K Nishikura
Keyword(s):  
Rate Constants ◽  
Imidazole Ring ◽  
Bohr Effect ◽  
Human Haemoglobin ◽  
First Order ◽  
Ph Values ◽  
Pseudo First Order ◽  
Ph Dependent ◽  
Alkaline Bohr Effect ◽  
Total Alkaline

Human carbonmonoxy- and deoxy-haemoglobins were incubated at 37 degrees C in 3H2O at various pH values to measure the pH-dependent hydrogen–tritium exchange at the C-2 position of the imidazole ring of histidine-122alpha. To obtain the pseudo-first-order rate constants for the exchange, k, the two peptides containing histidine-122alpha were isolated and the amounts of tritium incorporated were determined. The rate constants gave pK values for the histidine of 6.1 in carbonmonoxyhaemoglobin and 6.6 in deoxyhaemoglobin, showing that it contributes about 20% to the total alkaline Bohr effect and about 10% at pH7.4.

Unusual chemical properties of the amino groups of insulin: implications for structure–function relationship

1979 ◽  
Vol 57 (6) ◽  
pp. 489-496 ◽  
Author(s):  
Marla G. Sheffer ◽  
Harvey Kaplan
Keyword(s):  
Carbon Dioxide ◽  
Acetic Anhydride ◽  
Chemical Properties ◽  
Amino Terminus ◽  
Amino Group ◽  
Amino Groups ◽  
Ph Values ◽  
Function Relationship ◽  
Ph Range ◽  
Association State

The chemical properties of the three amino groups of insulin were obtained at 10 and 37 °C using the competitive labelling technique with acetic anhydride as the labelling reagent. At 10 °C, pK values of 7.9, 7.2, and 7.8 were found for the glycyl A1, phenylalanyl B1, and lysyl B29 amino groups. When compared with standard amino compounds by means of a Brønsted plot, the two amino-termini were found to be 'super-reactive' and the lysyl ε-amino group buried. In the presence of carbon dioxide at physiological pH values, all three amino groups became much less reactive indicating that they had reacted to form carbamino derivatives. Above pH 8 the reactivities of the glycyl amino terminus and ε-amino group increase sharply indicating that insulin is undergoing a conformational change which is most likely a change in its association state. At 37 °C the amino groups do not titrate normally but exhibit sharp increases in reactivity over the physiological pH range with the midpoints in the pH reactivity profiles between pH values of 7.0 and 7.3. This behaviour is interpreted as a rapid disaggregation of insulin to form monomers as a result of the ionization of the amino groups. It is concluded that at physiological pH and temperature all three amino groups are deprotonated.

scholarly journals The binding of carbon dioxide by horse haemoglobin

1971 ◽  
Vol 124 (1) ◽  
pp. 31-45 ◽  
Author(s):  
J. V. Kilmartin ◽  
L. Rossi-Bernardi
Keyword(s):  
Carbon Dioxide ◽  
Bohr Effect ◽  
Alkaline Ph ◽  
Amino Groups ◽  
Expected Number ◽  
Physiological Conditions ◽  
Alkaline Bohr Effect ◽  
Ph Range ◽  
The Hill ◽  
Β Chain

1. Three modified horse haemoglobins have been prepared: (i) αc2βc2, in which both the α-amino groups of the α- and β-chains have reacted with cyanate, (ii) αc2β2, in which the α-amino groups of the α-chains have reacted with cyanate, and (iii) α2βc2, in which the two α-amino groups of the β-chain have reacted with cyanate. 2. The values of n (the Hill constant) for αc2βc2, α2βc2 and αc2β2 were (respectively) 2.5, 2.0 and 2.6, indicating the presence of co-operative interactions between the haem groups for all derivatives. 3. In the alkaline pH range (about pH8.0) all the derivatives show the same charge as normal haemoglobin whereas in the acid pH range (about pH6.0) αc2βc2 differs by four protonic charges and αc2β2, α2βc2 by two protonic charges from normal haemoglobin, indicating that the expected number of ionizing groups have been removed. 4. αc2β2 and αc2βc2 show a 25% decrease in the alkaline Bohr effect, in contrast with α2βc2, which has the same Bohr effect as normal haemoglobin. 5. The deoxy form of αc2βc2 does not bind more CO2 than the oxy form of αc2βc2, whereas αc2β2 and α2βc2 show intermediate binding. 6. The results reported confirm the hypothesis that, under physiological conditions, haemoglobin binds CO2 through the four terminal α-amino groups and that the two terminal α-amino groups of α-chains are involved in the Bohr effect.

scholarly journals Reactivity and Ionization Constants of the Lysine Residues in Apovitellenin I of Emu Egg Yolk Low-density Lipoprotein by Competitive Labelling

1975 ◽  
Vol 28 (6) ◽  
pp. 433
Author(s):  
Theo AA Dopheide
Keyword(s):  
Acetic Anhydride ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Egg Yolk ◽  
Ionization Constants ◽  
Low Density ◽  
Amino Groups ◽  
Ph Values ◽  
Titration Curves ◽  
Lysine Residues

Competitive labelling with [14C]acetic anhydride over a range of pH values has been used to explore the surface topography of the apovitellenin I moiety in emu egg yolk low-density lipoprotein. The reaction of the lysine e-amino groups with acetic anhydride has been related to pH in a set of titration curves; from these, the reactivities relative to alanine and the ionization constants of all but the amino terminallysines have been determined.

scholarly journals An Investigation on the Turbidity Removal from Natural Stone Processing Plant Wastewater by Flocculation

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Savas OZUN ◽  
Dilan AGIRTMIS ULUS
Keyword(s):  
Molecular Weight ◽  
Fine Particles ◽  
Natural Stone ◽  
Processing Plant ◽  
Test Results ◽  
Alkaline Ph ◽  
Turbidity Removal ◽  
Ph Values ◽  
Ph Dependent ◽  
Removal Efficiencies

This study aimed to determine the effects of three different high molecular weight (HMW) flocculants (anionic, cationic and non-ionicflocculants) on the fine particles removal from natural stone (foid-bearing rock) processing plant wastewater at alkaline pH conditions.The test results were investigated in terms of turbidity values depending on pH of the medium, flocculant concentration and time (0–60min). According to the results obtained, the turbidity values of the wastewater in the absence of the flocculants were pH dependent anddecreased as the pH increased, resulted in the minimum turbidity values at pH 12. In the presence of the flocculants, the pH dependedturbidity removal efficiencies varied with flocculant type, flocculant concentration and time. The best results were obtained at highlyalkaline pH values (pH 12) with the turbidity removal efficiency of ≤99% in the presence of non-ionic flocculant. In the case of anionicand cationic flocculants, the minimum turbidity values were also obtained at pH 12 with turbidity removal efficiencies over 90%.

scholarly journals Таблеткові суміші, що містять іммобілізований лізоцим і кверцетин: отримання, властивості

2017 ◽  
Author(s):  
I. I. Romanovska ◽  
S. S. Dekina ◽  
O. V. Sevastyanov ◽  
Ye. A. Rogozha
Keyword(s):  
Enzyme Activity ◽  
Chemical Properties ◽  
Lysozyme Activity ◽  
Biologically Active ◽  
Alkaline Ph ◽  
Acidic Media ◽  
Ph Profile ◽  
Ph Values ◽  
Physico Chemical ◽  
Different Origin

Introduction. Lysozyme (EC 3.2.1.17), which has antibacterial, anti-inflammatory, immunomodulatory actions is increasingly used in medicine in a different dosage forms: tablets, wound coatings, capsules, gels, etc. Tablet is a convenient dosage form for usage of lysozyme in combination with other biologically active substances. The targeted stabilization of enzyme by immobilization into polymeric matrices determines the relevance of tablet form development of complex compositions of lysozyme and quercetin.The aim of the study – development of tablet blends of complex preparation of immobilized lysozyme and quercetin, their quantitative determination and the study of the properties of active substances.Methods of the research. Lysozyme activity was determined by bacteriolytic method. The protein content was controlled according to Lowry-Hartree, quercetin – using zirconium chloride.Results and Discussion. Using the earlier obtained data about the interaction of lysozyme with polymeric supports of different origin and structure, for the development of tableting mixtures with lysozyme and quercetin, as polymeric binders the poly-N-vinylpyrrolidone, sodium salt of carboxymethyl cellulose and gelatin were chosen. The comparative analysis of physico-chemical properties of immobilized in polymers lysozyme had shown prospects of gelatin usage as a matrice, which promotes widening of pH-profile of enzyme activity both in areas of acidic and alkaline pH values, stability in acidic media. For making the lysozyme and quercetin – containing tableting mixtures, the fillers, disintegrants, flavours and wet granulation method were chosen. The total preservation of lysozyme activity and quercetin content in obtained granules was shown.conclusions. Tablet mixtures with lysozyme and quercetin with usage of polymeric carriers of different origin and structure were developed. The analysis of biochemical and physico-chemical properties of immobilized lysozyme had shown prospects of gelatin usage as a matrice. Immobilization promotes widening of pH-profile of enzyme activity both in areas of acidic and alkaline pH values, stability in acidic media. 

scholarly journals Unmasking of histone amino groups in chromatin at high pH

1976 ◽  
Vol 159 (1) ◽  
pp. 173-175 ◽  
Author(s):  
B L Malchy ◽  
H Kaplan
Keyword(s):  
Acetic Anhydride ◽  
Amino Groups ◽  
High Ph ◽  
Ph Values ◽  
Ph Range

The reactivity of the amino groups of histones in chromatin towards acetic anhydride was determined as a function of pH. In the pH range 7-10 the vast majority of amino groups in all five histones are buried. However, at higher pH values some of the histone amino groups become exposed, and the higher the lysine:arginine ratio for the histone the greater was the degree of unmasking observed. At pH 11.8 histone I appears to be completely dissociated, histones IIB1 and IIb2 have approx. 55% of the amino groups unmasked, and histones III and IV have approx. 25% of the amino groups unmasked.

Investigation of Some Water Quality Parameters of Pond Water under Mymensingh Municipality

2015 ◽  
Vol 8 (1) ◽  
pp. 85-89
Author(s):  
F Zannat ◽  
MA Ali ◽  
MA Sattar
Keyword(s):  
Water Quality ◽  
Water Samples ◽  
Chemical Properties ◽  
Pond Water ◽  
Quality Parameters ◽  
Water Quality Parameters ◽  
Urban Region ◽  
Mn Toxicity ◽  
Ph Values ◽  
Drinking Water Standard

A study was conducted to evaluate the water quality parameters of pond water at Mymensingh Urban region. The water samples were collected from 30 ponds located at Mymensingh Urban Region during August to October 2010. The chemical analyses of water samples included pH, EC, Na, K, Ca, S, Mn and As were done by standard methods. The chemical properties in pond water were found pH 6.68 to 7.14, EC 227 to 700 ?Scm-1, Na 15.57 to 36.00 ppm, K 3.83 to 16.16 ppm, Ca 2.01 to 7.29 ppm, S 1.61 to 4.67 ppm, Mn 0.33 to 0.684 ppm and As 0.0011 to 0.0059 ppm. The pH values of water samples revealed that water samples were acidic to slightly alkaline in nature. The EC value revealed that water samples were medium salinity except one sample and also good for irrigation. According to drinking water standard Mn toxicity was detected in pond water. Considering Na, Ca and S ions pond water was safe for irrigation and aquaculture. In case of K ion, all the samples were suitable for irrigation but unsuitable for aquaculture.J. Environ. Sci. & Natural Resources, 8(1): 85-89 2015

scholarly journals 3P037 pH-dependent conformational change of equine beta-lactoglobulin

2004 ◽  
Vol 44 (supplement) ◽  
pp. S199
Author(s):  
M. Ohkouchi ◽  
K. Nagashima ◽  
Y. Yamada ◽  
M. Ikeguchi
Keyword(s):  
Conformational Change ◽  
Ph Dependent ◽  
Beta Lactoglobulin
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