Interference of Good's buffers and other biological buffers with protein determination

doi:10.1016/0003-2697(91)90210-K

Analytical Biochemistry

Volume 192, Issue 1, January 1991, Pages 215-218

https://doi.org/10.1016/0003-2697(91)90210-K Get rights and content

Abstract

Interference of low concentrations of Hepes and other buffers commonly used in protein determination was studied. The data show that some of these buffers interfere to differing degrees with protein determination according to the Lowry method. A study of the structure-interference relationship suggests that the group ethanolamine is involved in this interference. No interference was observed when protein was measured using bicinchonic acid at the same concentration as the Lowry reagent.

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Cited by (23)

Nickel exchange between aqueous Ni(II) and deep-sea ferromanganese nodules and crusts
2019, Chemical Geology
Citation Excerpt :
Structural modification and partial reduction of Mn oxide substrates has been observed following hydration with HEPES during atom exchange experiments between vernadite and Mn(II)aq, which has been attributed to piperazine moieties on the HEPES buffer molecules (Elzinga and Kustka, 2015). In contrast, MOPS and MES buffers used in this study have long been considered either non-complexing tertiary amine buffer compounds (Kandegedara and Rorabacher, 1999; Kaushal and Barnes, 1986; Lleu and Rebel, 1991; Yu et al., 1997) or weaker reductants than HEPES due to the presence of a morpholine rather than a piperazine ring (Lleu and Rebel, 1991; Wang and Sayre, 1989). MES, however, has been found to induce partial reduction of synthetic Mn(IV) oxides (Hinkle et al., 2016).
Deep-sea ferromanganese (Fe-Mn) nodules and crusts are rich in traditional and non-traditional metals with both current and emerging economic value. Mn(III,IV) oxides (e.g., phyllomanganates) are important host phases for these metals (e.g., Ni), which are structurally incorporated during nodule and Fe-Mn crust formation. Recrystallization of phyllomanganates can be catalyzed by aqueous Mn(II) (Mn(II)_aq) during (bio)geochemical Mn redox cycling. The fate of structurally incorporated metals during such recrystallization of Mn(III,IV) oxides remains, however, poorly constrained. Here, we use a ⁶²Ni isotope tracer to determine the exchangeability of dissolved Ni with structurally incorporated Ni in two deep-sea Fe-Mn nodules and one Fe-Mn crust. Ni exchange between solid and solution was investigated during reactions in 1 mM Mn(II)_aq and in Mn(II)-free solutions under variable pH conditions (pH 5.5 and 7.5) over time. Sample characterization shows that all samples are of hydrogenetic or mixed hydrogenetic-diagenetic origin and Ni is preferentially associated with the phyllomanganates. Our Ni exchange experiments reveal that in some samples up to 25% of incorporated Ni is exchangeable with the fluid after 14 days. The prevalent reaction pathways exhibit pH-dependent behavior during phyllomanganate recrystallization and differ between sample types, with Mn(II)_aq enhancing Ni exchange in the Fe-Mn crust-fluid system and Ni exchange being independent of Mn(II)_aq concentrations in the Fe-Mn nodule-fluid systems. The exchangeability of structurally-incorporated Ni in Fe-Mn nodules and crusts indicates a labile behavior that potentially makes it available for biogeochemical processes in the marine environment.
Volumetric properties of MES, MOPS, MOPSO, and MOBS in water and in aqueous electrolyte solutions
2010, Thermochimica Acta
4-Morpholineethanesulfonic acid (MES), 4-morpholinepropanesulfonic acid (MOPS), 3-morpholino-2-hydroxypropanesulfonic acid (MOPSO), and 4-(N-morpholino)butanesulfonic acid (MOBS), are useful for pH control as standard buffers in the physiological region of 5.5–6.7 for MES, 6.5–7.9 for MOPS, 6.2–7.6 for MOPSO, and 6.9–8.3 for MOBS, respectively. On the basis of density measurements at 298.15 K, the apparent molar volumes, V_ϕ, of the above-mentioned buffers in water and in (0.05, 0.16, and 0.25) mol kg⁻¹ aqueous solutions of NaCl, KCl, KBr, and CH₃COOK have been calculated. The partial molar volumes at infinite dilution, $V_{ϕ}^{o}$ , obtained from V_ϕ, have been used to calculate the volume of transfer, $Δ_{t r} V_{ϕ}^{o}$ , from water to aqueous electrolyte solutions. It was found that both $V_{ϕ}^{o}$ and $Δ_{t r} V_{ϕ}^{o}$ vary linearly with increasing the number of carbon atoms in the alkyl group side chain of the zwitterionic buffers. These linear correlations have been utilized to estimate the contributions of the zwitterionic end group (morpholinium ion, –SO₃⁻) and –CH₂– group to $V_{ϕ}^{o}$ and $Δ_{t r} V_{ϕ}^{o}$ . The values of $V_{ϕ}^{o}$ and $Δ_{t r} V_{ϕ}^{o}$ for some functional group contributions of the zwittierionic buffers with salts have also been reported.
Cadmium transport by the gut and Malpighian tubules of Chironomus riparius
2009, Aquatic Toxicology
Many aquatic insects are very insensitive to cadmium in short-term laboratory studies. LC50 values for larvae of the midge Chironomus riparius are over 25,000 times the Criterion Maximum Concentration in the United States Environmental Protection Agency (U.S. EPA (2000)) species sensitivity distribution (SSD). Excretion or sequestration of cadmium may contribute to insensitivity and we have therefore examined cadmium transport by isolated guts and renal tissues of C. riparius larvae. Regional differences of Cd transport along the gut were identified using a Cd²⁺-selective microelectrode in conjunction with the Scanning Ion-Selective Electrode Technique (SIET). Cd is transported into the anterior midgut (AMG) cells from the lumen and out of the cells into the hemolymph. The transport of Cd from the gut lumen to the hemolymph exposes other tissues such as the nervous system and muscles to Cd. The gut segments which remove Cd from the hemolymph at the highest rate are the posterior midgut (PMG) and the ileum. In addition, assays using an isolated Malpighian (renal) tubule preparation have shown that the Malpighian tubules (MT) both sequester and secrete Cd. For larvae bathed in 10 μmol l⁻¹ Cd, the tubules can secrete the entire hemolymph burden of Cd in ∼15 h.
Interference by Mes [2-(4-morpholino)ethanesulfonic acid] and related buffers with phenolic oxidation by peroxidase
2007, Free Radical Biology and Medicine
While characterizing the kinetic parameters of apoplastic phenolic oxidation by peroxidase, we found anomalies caused by the Mes [2-(4-morpholino)ethanesulfonic acid] buffer being used. In the presence of Mes, certain phenolics appeared not to be oxidized by peroxidase, yet the oxidant, H₂O₂, was utilized. This anomaly seems to be due to the recycling of the phenolic substrate. The reaction is relatively inefficient, but at buffer concentrations of 10 mM or greater the recycling effect is nearly 100% with substrate concentrations less than 100 μM. The recycling effect is dependent on substrate structure, occurring with 4′-hydroxyacetophenone but not with 3′,5′-dimethoxy-4′-hydroxyacetophenone (acetosyringone). Characterization of the reaction parameters suggests that the phenoxyl radical from the peroxidase reaction interacts with Mes, causing the reduction and regeneration of the phenol. Similar responses occurred with related buffers such as Hepes [4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid] and Pipes [piperazine-1,4-bis(2-ethanesulfonic acid)]. Results from this work and other reports in the literature indicate that great care is required in interpreting any results involving these buffers under oxidizing conditions.
Oxidation of Good's buffers by hydrogen peroxide
2006, Analytical Biochemistry
Good’s zwitterionic buffers are widely used in biological and biochemical research in which hydrogen peroxide is a solution component. This study was undertaken to determine whether Good’s buffers exhibit reactivity toward H₂O₂. It is found that H₂O₂ oxidizes both morpholine ring-containing buffers (e.g., Mops, Mes) and piperazine ring-containing zwitterionic buffers (e.g., Pipes, Hepes, and Epps) to produce their corresponding N-oxide forms. The percentage of oxidized buffer increases as the concentration of H₂O₂ increases. However, the rate of oxidation is relatively slow. For example, no oxidized Mops was detected 2 h after adding 0.1 M H₂O₂ to 0.1 M Mops (pH 7.0), and only 5.7% was oxidized after 24 h exposure to H₂O₂. Thus, although all of these buffers can be oxidized by H₂O₂, their slow reaction does not significantly perturb levels of H₂O₂ in the time frame and at the concentrations of most biochemical studies. Therefore, the previously reported rapid loss of H₂O₂ produced from the ferroxidase reaction of ferritin is unlikely due to reaction of H₂O₂ with buffer, a conclusion supported by the fact that H₂O₂ is also lost rapidly when the solution pH of the ferroxidase reaction is controlled by a pH stat apparatus in the absence of buffer.
Cu(II) complexation by "non-coordinating" N-2- hydroxyethylpiperazine-N′-2-ethanesulfonic acid (HEPES buffer)
2005, Journal of Inorganic Biochemistry
The combined potentiometric and spectroscopic studies of interactions of N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid (HEPES) with Cu(II) demonstrated that this popular buffer, commonly labelled as “non-coordinating” forms a CuL⁺ complex, with the log β_CuL value of 3.22. This complex undergoes alkaline hydrolysis above pH 6, resulting in Cu(OH)₂ precipitation. However, the presence of HEPES at a typical concentration of 100 mM at pH 7.4 elevates the apparent binding constant, being determined for a complex of another ligand, by a factor of 80. HEPES does not form ternary complexes with aminoacids Ala, Trp, and His, but may do so with other bioligands, such as nucleotides. Therefore, HEPES can still be recommended for Cu(II) studies in place of other common buffers, such as Tris and phosphate, but appropriate corrections and precautions should be applied in quantitative experiments.

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Interference of Good's buffers and other biological buffers with protein determination

Abstract

Anal. Biochem

Anal. Biochem

Anal. Biochem

Anal. Biochem

Anal. Biochem