On the chemical basis of the Lowry protein determination

Legler, Günter; Müller‐Platz, C.; Mentges-Hettkamp, Maria; Pflieger, Gabirele; Jülich, Elisabeth

doi:10.1016/0003-2697(85)90511-1

Cited by 79 publications

(36 citation statements)

References 8 publications

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“…This procedure is based on Peterson's modification. 14 An alkaline cupric tartrate reagent complexes with the peptides bonds and forms a purple color, in which absorbance is read at 543 nm. Standard and reactive of Lowry and Folin were from Sigma.…”

Section: Analytic Methodsmentioning

confidence: 99%

Age- and Sodium-Sensitive Hypertension and Sex-Dependent Renal Changes in Rats With a Reduced Nephron Number

et al. 2008

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Abstract-We have demonstrated that the reduction of angiotensin II effects during the nephrogenic period reduces the nephron number and induces the development of hypertension. The hypotheses examined are that this reduction of angiotensin effects leads to the development of an age-dependent sodium sensitive hypertension and that the hypertension is angiotensin II dependent. Newborn rats were treated with an angiotensin II type 1 receptor antagonist during the first 2 weeks of age. At 3 to 4 and 11 to 12 months of age, changes in systolic blood pressure, proteinuria, and renal function in response to a prolonged high sodium intake were examined. The basal blood pressure response to the administration of the angiotensin II receptor antagonist was also evaluated at both ages. Basal blood pressure was similarly elevated (PϽ0.05) in male and female treated rats, and the increment was age dependent. High sodium intake only elicited a blood pressure elevation (136Ϯ1 to 154Ϯ3 mm Hg; PϽ0.05) and a decrease in glomerular filtration rate (28%; PϽ0.05) at 11 to 12 months in treated rats. Blockade of angiotensin II receptors during renal development induced an increase (PϽ0.05) in proteinuria that was age and sex dependent, but high sodium intake only induced an elevation in proteinuria in the younger rats (50%; PϽ0.05). Hypertension was maintained by angiotensin II at both ages because blood pressure decreased to normal levels after treatment with an angiotensin II type 1 receptor antagonist. This study shows that the reduction of angiotensin II effects during the nephrogenic period modifies renal function and induces the development of an angiotensin II-dependent hypertension that becomes sodium sensitive during aging. T he importance of nephron number in the development of hypertension and renal dysfunction is supported by experimental and clinical studies [1][2][3][4][5][6][7][8][9] demonstrating that the alteration of nephrogenesis regulation leads to significant changes in arterial pressure and renal function during the adulthood. These effects of the reduction in nephron number during renal development seem to be more significant than those elicited by a decrease in nephron number later in life. 2 One mechanism that is involved in the regulation of nephrogenesis is the renin-angiotensin system (RAS). The role of RAS has been confirmed in previous studies of our group demonstrating that the blockade of the angiotensin II (Ang II) type 1 (AT 1 ) receptors during the late nephrogenic period reduces nephron number by 37%, induces the development of hypertension, and elicits important renal changes that are greater in male than in female rats. 7,8 An age-and sexdependent increment in proteinuria is observed in rats when the effects of Ang II via the AT 1 receptor are reduced during the nephrogenic period. 7,8 These rats also have a decrease in renal functional reserve, because the response to an increment in plasma amino acid levels is deteriorated, and their renal excretory ability to eliminate an acute sodium load is im...

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Section: Analytic Methodsmentioning

confidence: 99%

Age- and Sodium-Sensitive Hypertension and Sex-Dependent Renal Changes in Rats With a Reduced Nephron Number

et al. 2008

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“…For S. latissima, the protein levels of both the crude biomass and the extracts were higher when recorded using the Lowry method compared to those obtained with the total amino acid analysis method, resulting in more similar protein yield values with both analysis methods. Both the pigment content and the type of amino acids present (Legler et al 1985) could affect the total protein results found using the Lowry method. Selective retention of certain amino acids and pigments in the extracts could affect the measured values recorded.…”

Section: Discussionmentioning

confidence: 99%

Production of protein extracts from Swedish red, green, and brown seaweeds, Porphyra umbilicalis Kützing, Ulva lactuca Linnaeus, and Saccharina latissima (Linnaeus) J. V. Lamouroux using three different methods

et al. 2018

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The demand for vegetable proteins increases globally and seaweeds are considered novel and promising protein sources. However, the tough polysaccharide-rich cell walls and the abundance of polyphenols reduce the extractability and digestibility of seaweed proteins. Therefore, food grade, scalable, and environmentally friendly protein extraction techniques are required. To date, little work has been carried out on developing such methods taking into consideration the structural differences between seaweed species. In this work, three different protein extraction methods were applied to three Swedish seaweeds (Porphyra umbilicalis, Ulva lactuca, and Saccharina latissima). These methods included (I) a traditional method using sonication in water and subsequent ammonium sulfate-induced protein precipitation, (II) the pH-shift protein extraction method using alkaline protein solubilization followed by isoelectric precipitation, and (III) the accelerated solvent extraction (ASE®) method where proteins are extracted after pre-removal of lipids and phlorotannins. The highest protein yields were achieved using the pH-shift method applied to P. umbilicalis (22.6 ± 7.3%) and S. latissima (25.1 ± 0.9%). The traditional method resulted in the greatest protein yield when applied to U. lactuca (19.6 ± 0.8%). However, the protein concentration in the produced extracts was highest for all three species using the pH-shift method (71.0 ± 3.7%, 51.2 ± 2.1%, and 40.7 ± 0.5% for P. umbilicalis, U. lactuca, and S. latissima, respectively). In addition, the pH-shift method was found to concentrate the fatty acids in U. lactuca and S. latissima by 2.2 and 1.6 times, respectively. The pH-shift method can therefore be considered a promising strategy for producing seaweed protein ingredients for use in food and feed.

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“…19,20 Total organic carbon (TOC) was determined using a Shimadzu 5000A TOC analyzer. Hydrodynamic diameter of EPS was determined using the Zetasizer.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Influence of Extracellular Polymeric Substances on the Long-Term Fate, Dissolution, and Speciation of Copper-Based Nanoparticles

Adeleye

Conway

Pérez

et al. 2014

Environ. Sci. Technol.

216

217

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ABSTRACT:The influence of phytoplankton-derived soluble extracellular polymeric substances (EPS), pH, and ionic strength (IS) on the dissolution, speciation, and stability of nano-CuO, nano-Cu, and Kocide (a micron sized Cu(OH) 2 -based fungicide) was investigated over 90 days. EPS improved the stability of commercial copper-based nanoparticles (CBNPs) in most conditions, in addition to influencing their dissolution. The dissolution rate was pH 4 ≫ pH 7 > pH 11. The presence of EPS correlated with higher dissolved Cu at pH 7 and 11, and lower dissolved Cu at pH 4. More dissolution was observed at higher IS (NaCl) due to complexation with Cl − . Dissolution of nano-CuO at pH 7 increased from 0.93% after 90 days (without EPS) to 2.01% (with 5 mg-C EPS/L) at 10 mM IS. Nano-CuO dissolved even more (2.42%) when IS was increased to 100 mM NaCl (with EPS). The ratio of freeCu 2+ /total dissolved Cu decreased in the presence of EPS, or as pH and/or IS increased. On a Cu mass basis, Kocide had the highest dissolved and suspended Cu at pH 7. However, dissolution of nano-Cu resulted in a higher fraction of free Cu 2+ , which may make nano-Cu more toxic to pelagic organisms. ■ INTRODUCTIONGlobal production of copper-based nanoparticles (CBNPs) was estimated at ∼200 t/yr in 2010, and is increasing. 1 CBNPs have found use in cosmetics, pigments, paints and coatings, electronics, and pesticides. 2−4 These applications may lead to direct exposure of CBNPs to the environment due to normal use, product wear-and-tear, and/or end-of-life disposal. 1 Toxicity of CBNPs and composites to organisms has been demonstrated. 2,5−8 It is therefore important to understand the long-term fate and transformations of these materials in aquatic systems in order to predict exposure to at-risk organisms.Stability and dissolution of engineered nanoparticles (ENPs) depend on ionic strength (IS), pH, and natural organic material (NOM). 9−12 Rapid aggregation of nano-Cu was reported in freshwater by Griffitt et al. 5 The authors also found that less than 0.1% of the nano-Cu dissolved in 48 h in the freshwater media used (pH 8.2). 98% dissolution of nano-Cu was however reported at pH 6 in "uterine-fluid" after a week, 13 demonstrating the importance of pH and media composition on CBNPs' dissolution. Mudunkotuwa and co-workers 14 reported increased dissolution of aged and new CBNPs in the presence of organic acids. Similarly, Worthington et al. 15 showed that the chitosan improved stability and dissolution of nano-Cu. To our knowledge, no studies have previously investigated the effects of naturally occurring NOM such as extracellular polymeric substances (EPS) on the stability and dissolution of CBNPs. EPS are synthesized by microorganisms, which are abundant in natural aquatic systems. EPS are mainly composed of polysaccharides, proteins, nucleic acids, and other polymers; and their composition may vary spatially and temporally even within the same species. 16 EPS may interact with ENPs, thus affecting their fate and transformation. 17 Additional...

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On the chemical basis of the Lowry protein determination

Cited by 79 publications

References 8 publications

Age- and Sodium-Sensitive Hypertension and Sex-Dependent Renal Changes in Rats With a Reduced Nephron Number

Age- and Sodium-Sensitive Hypertension and Sex-Dependent Renal Changes in Rats With a Reduced Nephron Number

Production of protein extracts from Swedish red, green, and brown seaweeds, Porphyra umbilicalis Kützing, Ulva lactuca Linnaeus, and Saccharina latissima (Linnaeus) J. V. Lamouroux using three different methods

Influence of Extracellular Polymeric Substances on the Long-Term Fate, Dissolution, and Speciation of Copper-Based Nanoparticles

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