Thermal denaturation of plastocyanin: The effect of oxidation state, reductants, and anaerobicity

Gross, Elizabeth; Draheim, James E.; Curtiss, April; Crombie, B.; Scheffer, Ashley; Pan, Baocheng; Chiang, Chia-Chien; Lopez, Arbil

doi:10.1016/0003-9861(92)90429-z

Cited by 23 publications

(22 citation statements)

References 24 publications

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“…Although these minima are somewhat red-shifted with respect to that seen in the "canonical" β-sheet form of poly-L-lysine 66,67 (218 nm), they are consistent with minima observed in β-sheet-rich proteins such as concanavalin A (223 nm) 68 or plastocyanin (224 nm). 69 Additionally, we found no trend of chromic shift in the minima of the poly(Q) films with increasing glutamine number. Since film CD spectra cannot be corrected for concentration in the way that solution CD spectra can, we compared the film data by normalizing the CD signal to the absorbance at 215 nm (obtained from dynode voltage) to correct approximately for the amount of peptide deposited on the plate.…”

Section: Resultsmentioning

confidence: 61%

Flanking Polyproline Sequences Inhibit β-Sheet Structure in Polyglutamine Segments by Inducing PPII-like Helix Structure

Darnell

Orgel

Pahl

et al. 2007

Journal of Molecular Biology

150

200

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Section: Resultsmentioning

confidence: 61%

Flanking Polyproline Sequences Inhibit β-Sheet Structure in Polyglutamine Segments by Inducing PPII-like Helix Structure

Darnell

Orgel

Pahl

et al. 2007

Journal of Molecular Biology

150

200

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“…The formation of two denatured species during the unfolding of plastocyanin has previously been reported for spinach Pc following thermal unfolding by circular dichroism (16), but no EPR data are available. It was not possible to confidently assign any of these species to either square planar copper bound to the protein or free copper released into the solution, contrary to what has been published in the literature as a clean outcome of similar studies (17).…”

Section: Resultsmentioning

confidence: 98%

“…Earlier thermal stability studies on Pc have focused on the protein isolated from spinach (16)(17)(18). Initial results showed that, under aerobic conditions, the reduced protein was more thermostable (T M ) 71°C) than the oxidized one (T M ) 61°C) (16).…”

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confidence: 99%

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A Thermal Unfolding Study of Plastocyanin from the Thermophilic CyanobacteriumPhormidium laminosum

et al. 2004

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The thermal unfolding of the plastocyanin from Phormidium laminosum, a thermophilic cyanobacterium, is herein described. The main objective of this work is to identify structural factors responsible for the higher stability observed in proteins from thermophilic organisms. With the aid of fluorescence spectroscopy, EPR, and NMR, the factors influencing the unfolding process of the protein were investigated, and procedures for its study have been standardized. The different spectroscopic techniques used provided consistent results showing that the thermal unfolding of plastocyanin is irreversible under all the conditions investigated and that this irreversibility does not appear to be related to the presence of oxygen. The oxidized plastocyanin species has proven to be more stable than the reduced one, with respect to both the required temperature for protein unfolding (up to a 9 degrees C difference between the two forms) and the kinetics of the process. The behavior of this plastocyanin contrasts with that of other cupredoxins whose unfolding had previously been studied. The unfolding pH dependence and kinetic studies indicate a process with a tight control around the physiological pH in which plastocyanin plays its redox role and the protein's isoelectric point (5.2), suggesting a close compromise between function and stability.

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“…19,20 However, other reports have suggested that Fe͑CN͒ 6 3−/4− interactions with proteins are either more complex 21 or in some cases benign. 22 Fe͑CN͒ 6 3−/4− has also been reported to disrupt the formation of Authiol self-assembled monolayers ͑SAM͒ through mild etching of Au. 23 Although the Fe͑CN͒ 6 3− complex is quite stable, a small concentration of free CN − will always be present.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Impedance Biosensor for Glucose Detection Utilizing a Periplasmic E. coli Receptor Protein

Wang¹,

Carmon

Luck

et al. 2005

Electrochem. Solid-State Lett.

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We report the development of a reagentless electrochemical impedance biosensor for glucose that employs the D-glucose/galactose receptor from E. coli for direct glucose detection. The biological platform for this sensor is an Au surface to which the protein is immobilized through formation of an Au-S bond to a genetically engineered cysteine residue at the N-terminus. The impedance signal detects the extensive ligand-induced domain motion within the protein upon glucose binding. We show the applicability of impedance spectroscopy in conjunction with periplasmic binding proteins as a general method for detecting small molecules.For control of diabetes mellitus, maintenance of blood glucose concentrations within the normal physiological range is critical to minimizing diabetic complications. As a result, accurate in vivo and in vitro measurement of glucose concentration in physiological fluids has long been a central goal of biosensor research. Traditionally, glucose biosensors employ indirect detection of the products of the glucose oxidase or glucose dehydrogenase reactions, although direct detection has also been reported. In general, glucose oxidase has been the favored biological recognition element due to the high binding specificity, high turnover rate, and high stability of this enzyme. However, indirect detection of hydrogen peroxide, or other products, often suffers from low selectivity arising from chemical interference by other easily reducible substances, such as ascorbate and urate. Direct detection suffers from two general drawbacks that limit the efficiency with which electrons can be collected: proteins are usually electrically insulating, and the reaction site may be located far from the collection electrode. 1 In addition, electron transfer proteins are also required. To circumvent these problems, the current report focuses on direct glucose detection by electrochemical impedance using the D-glucose/galactose receptor ͑GGR͒ from E. coli.The potential use of the bacterial periplasmic binding protein superfamily ͑bPBP͒ in biosensors has arisen due to their solubility, stability and ability to reversibly bind a large variety of small ligands including sugars, amino acids, and inorganic ions. 2 These proteins comprise a large family of functionally similar receptors with a two-domain structure that exhibit a large hinge-twist conformational change upon ligand binding. Whereas the proteins are open and flexible when the ligand is absent, they are more structurally compact and closed when the ligand is bound. This large amplitude motion can be exploited for biosensor development of small molecules. [3][4][5][6] The GGR protein is specific for glucose or galactose and binds these ligands in the micromolar range, which is more sensitive than that needed for blood glucose. A number of groups have detected sugars by labeling this protein with fluorescent tags in sites where the chemical environment is altered during ligand binding. 7-10 Two recent studies have used surface plasmon resonance ͑SPR͒ methods w...

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Thermal denaturation of plastocyanin: The effect of oxidation state, reductants, and anaerobicity

Cited by 23 publications

References 24 publications

Flanking Polyproline Sequences Inhibit β-Sheet Structure in Polyglutamine Segments by Inducing PPII-like Helix Structure

Flanking Polyproline Sequences Inhibit β-Sheet Structure in Polyglutamine Segments by Inducing PPII-like Helix Structure

A Thermal Unfolding Study of Plastocyanin from the Thermophilic CyanobacteriumPhormidium laminosum

Electrochemical Impedance Biosensor for Glucose Detection Utilizing a Periplasmic E. coli Receptor Protein

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