Temperature‐Induced Unfolding of Ribonuclease A Embedded in Spherical Polyelectrolyte Brushes

Wittemann, Alexander; Ballauff, Matthias

doi:10.1002/mabi.200400133

Cited by 37 publications

(39 citation statements)

References 42 publications

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“…[55] (2) Previous studies by FT-IR have shown that the secondary structure of the adsorbed BSA, b-lactoglobulin and of ribonuclease A is nearly undisturbed. [58,62] Moreover, the activity of adsorbed enzymes as glucoamylase is largely preserved. [33] The same conclusion was drawn from a study of the fluorescence activity of the fluorescent protein mEosFP.…”

Section: Immobilization Of Proteins and Enzymes On Spherical Polyelecmentioning

confidence: 99%

Supramolecular Structures Generated by Spherical Polyelectrolyte Brushes and their Application in Catalysis

Lü

Wittemann

Ballauff

2009

Macromol. Rapid Commun.

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We survey recent studies on composite particles made from spherical polyelectrolyte brushes (SPB) and catalytically active nanoparticles or enzymes. SPB consist of a solid core (diameter: ca. 100 nm) onto which long chains of anionic or cationic polyelectrolyte (PE) are densely grafted ("PE brush"). Immersed in water the PE layer affixed to the colloidal core will swell due to the enormous osmotic pressure of the confined counterions ("osmotic brush"). This confinement of the counterions can be used to generate metal nanoparticles on the surface of the SPB. Moreover, enzymes can be immobilized within the PE layer. In both cases, the resulting composite particles are stable against coagulation and can be easily handled and filtered off. The catalytic activity of both systems is largely preserved in case of the enzymes, in case of the metal nanoparticles it is even enhanced. Thus, the SPB present an excellent carrier system for applications in catalysis.

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Section: Immobilization Of Proteins and Enzymes On Spherical Polyelecmentioning

confidence: 99%

Supramolecular Structures Generated by Spherical Polyelectrolyte Brushes and their Application in Catalysis

Lü

Wittemann

Ballauff

2009

Macromol. Rapid Commun.

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“…Recently, we found that BSA as well as other proteins strongly adsorb onto the SPB in aqueous solution if the ionic strength is low whereas no adsorption takes place at high concentrations of added salt [9,[17][18][19][20]. Hence, the adsorption of proteins takes place on the "wrong side" of the isoelectric point pI, that is, for a pH > pI so that the proteins are carrying more negative than positive charges.…”

Section: Introductionmentioning

confidence: 96%

“…Previous studies have shown that i) the secondary structure of the adsorbed BSA, β-lactoglobulin and of ribonuclease A is nearly fully preserved [17,19], ii) the proteins are evenly distributed within the brush layer [21,22], and iii) that the enzyme activity of adsorbed enzymes as e.g. glucoamylase is largely preserved [18,20].…”

Section: Introductionmentioning

confidence: 98%

Controlled Release of Proteins Bound to Spherical Polyelectrolyte Brushes

Wittemann¹,

Haupt²,

Ballauff³

2007

Zeitschrift Für Physikalische Chemie

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Polyelectrolyte Brushes / Protein / Adsorption / Albumin / CounterionsWe discuss the interaction of proteins dissolved in aqueous solution with spherical polyelectrolyte brushes (SPB). The SPB consist of a solid core particle of colloidal dimensions (ca. 100 nm in diameter) onto which long polyelectrolyte chains have been grafted. Immersed in aqueous solution of proteins these SPB will take up high amounts of protein if the ionic strength is low. At high ionic strength, however, virtually no protein will enter into the brush layer attached to the surface of the core particles. We show that bovine serum albumin (BSA) bound at low ionic strength will gradually be released upon raising the salt concentration in the solution in a well-controlled manner: For each raise of the ionic strength in solution there is a well-defined amount of protein that is released. We show that BSA adsorbed to a conventional carboxylated latex will not be released if treated in the same manner. All findings, namely the uptake of protein as well as the controlled release can be explained by the "counterion release force": Patches of positive charge on the surface of the proteins which are immersed in the brush layer become multivalent counterions of the polyelectrolyte chains thus releasing a concomitant number of counter-and coions. Release of counterions as induced by the adsorption of proteins is hence the main driving force for the polyelectrolyte-mediated protein adsorption (PMPA).

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“…It has recently been demonstrated that the unfolding of small globular proteins occurs via a twostate process, while the unfolding of larger proteins (>100 amino acids) becomes more complicated and often involves the formation of intermediate(s). [8][9][10] Protein unfolding can be affected by some factors such as pressure, 11 temperature, 12 pH, 13 and disulfide bond.…”

Section: Introductionmentioning

confidence: 99%

Effects of rare earth ions on the conformational stability of anticoagulation factor II from Agkistrodon acutus venom probed by fluorescent spectroscopy

Xu¹,

Chen²,

Zhang³

et al. 2006

Biopolymers

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Anticoagulation factor II (ACF II) isolated from the venom of Agkistrodon acutus is an activated coagulation factor X-binding protein in a Ca(2+)-dependent fashion with marked anticoagulant activity. The equilibrium unfolding of rare earth ions (RE(3+))-reconstituted ACF II in guanidine hydrochloride (GdnHCl) solution was studied by fluorescence. The GdnHCl-induced unfolding of RE(3+) (Nd(3+), Sm(3+), Eu(3+), Gd(3+))-reconstituted ACF II follows a three-state transition with a stable intermediate state. Substitutions of the RE(3+) ions for Ca(2+) in ACF II decrease the conformational stability of its native state but markedly increase the conformational stability of its intermediate state. The free energy change of RE(3+)-ACF II from the intermediate state to denatured state linearly increases with the increase of ionic potentials of bound metal ions (Ca(2+), Nd(3+), Sm(3+), Eu(3+), and Gd(3+)). The refolding of ACF II from the unfolded state to the intermediate state can be induced merely by adding 10 microM RE(3+) ions without changing the concentration of the denaturant. The kinetic results of the RE(3+)-induced refolding provide evidence indicating that the intermediate state of RE(3+)-ACF II consists of at least two refolding phases and that the refolding rate constant values of the faster phase decrease with the increase of the difference between the radii of Ca(2+) and RE(3+), but the refolding rate constant values of the slower phase are similar to each other. The results of this study indicate that the size of metal ion is the major factor responsible for the metal ion-induced conformational stabilization of the native ACF II, while the metal ionic potential plays a predominant role in stabilizing the conformation for the intermediate state.

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Temperature‐Induced Unfolding of Ribonuclease A Embedded in Spherical Polyelectrolyte Brushes

Cited by 37 publications

References 42 publications

Supramolecular Structures Generated by Spherical Polyelectrolyte Brushes and their Application in Catalysis

Supramolecular Structures Generated by Spherical Polyelectrolyte Brushes and their Application in Catalysis

Controlled Release of Proteins Bound to Spherical Polyelectrolyte Brushes

Effects of rare earth ions on the conformational stability of anticoagulation factor II from Agkistrodon acutus venom probed by fluorescent spectroscopy

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