Limits...
Rosin Surfactant QRMAE Can Be Utilized as an Amorphous Aggregate Inducer: A Case Study of Mammalian Serum Albumin.

Ishtikhar M, Chandel TI, Ahmad A, Ali MS, Al-Lohadan HA, Atta AM, Khan RH - PLoS ONE (2015)

Bottom Line: It was observed that a suitable molar ratio of protein to QRMAE surfactant enthusiastically induces amorphous aggregate formation at a pH above two units of pI.Rosin surfactant QRMAE-albumins interactions revealed a unique interplay between the initial electrostatic and the subsequent hydrophobic interactions that play an important role towards the formation of hydrophobic interactions-driven amorphous aggregate.Amorphous aggregation of proteins is associated with varying diseases, from the formation of protein wine haze to the expansion of the eye lenses in cataract, during the expression and purification of recombinant proteins.

View Article: PubMed Central - PubMed

Affiliation: Protein Biophysics Laboratory, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh - 202002, India.

ABSTRACT
Quaternary amine of diethylaminoethyl rosin ester (QRMAE), chemically synthesized biocompatible rosin based cationic surfactant, has various biological applications including its use as a food product additive. In this study, we examined the amorphous aggregation behavior of mammalian serum albumins at pH 7.5, i.e., two units above their isoelectric points (pI ~5.5), and the roles played by positive charge and hydrophobicity of exogenously added rosin surfactant QRMAE. The study was carried out on five mammalian serum albumins, using various spectroscopic methods, dye binding assay, circular dichroism and electron microscopy. The thermodynamics of the binding of mammalian serum albumins to cationic rosin modified surfactant were established using isothermal titration calorimetry (ITC). It was observed that a suitable molar ratio of protein to QRMAE surfactant enthusiastically induces amorphous aggregate formation at a pH above two units of pI. Rosin surfactant QRMAE-albumins interactions revealed a unique interplay between the initial electrostatic and the subsequent hydrophobic interactions that play an important role towards the formation of hydrophobic interactions-driven amorphous aggregate. Amorphous aggregation of proteins is associated with varying diseases, from the formation of protein wine haze to the expansion of the eye lenses in cataract, during the expression and purification of recombinant proteins. This study can be used for the design of novel biomolecules or drugs with the ability to neutralize factor(s) responsible for the aggregate formation, in addition to various other industrial applications.

No MeSH data available.


Related in: MedlinePlus

(A) Far-UV CD spectra of mammalian serum albumins at pH below two unit of proteins pI and (B) at pH above two unit of proteins pI in the absence and presence of rosin surfactant QRMAE. The experiment was performed after 60 min incubation at 65°C. [The presence of secondary structure, contents for α-class of protein was calculated by Chen et al. method that was further supported by K2D software analysis].
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4587963&req=5

pone.0139027.g005: (A) Far-UV CD spectra of mammalian serum albumins at pH below two unit of proteins pI and (B) at pH above two unit of proteins pI in the absence and presence of rosin surfactant QRMAE. The experiment was performed after 60 min incubation at 65°C. [The presence of secondary structure, contents for α-class of protein was calculated by Chen et al. method that was further supported by K2D software analysis].

Mentions: Far-UV CD measurements were used to determine the secondary structure change in the protein. The secondary structure consists of α-helix, β-sheet and random coil structure [29]. Two negative peaks of α-helix lies at 208 nm and 222 nm, one negative peak of β-sheet and one negative peak of random coil lies at 217 nm 197 nm, respectively [41]. Far and near-UV CD studies were used to determine the effect of QRMAE on the secondary and tertiary structure of proteins (albumins) at pH below and above two units of its pI. Proteins were incubated at 65°C for 1 h. It has been shown in Fig 5A that CD spectra of controls and QRMAE induced mammalian serum albumins at pH 3.5 (below two units of pI) exhibited two minima at 208 nm and 222 nm which indicated the formation of α-helical structures [42, 43]. On the other hand, at pH 7.5 (above two units of pI), a noticeable difference in the CD spectra of the albumins (Fig 5B) in the presence of rosin surfactant QRMAE was observed and the data obtained after % α-helisity calculation is listed in Table 1. A remarkable decrease in negative ellipticity of the QRMAE incubated proteins was observed, which indicated that the transformation of α-helical structure to β-sheet or random coil structure occurred due to aggregate formation. This confirmed that the cause of aggregation of albumins was QRMAE at pH two units above its pI and the protein structures still retained their α-helical and radom coil nature.


Rosin Surfactant QRMAE Can Be Utilized as an Amorphous Aggregate Inducer: A Case Study of Mammalian Serum Albumin.

Ishtikhar M, Chandel TI, Ahmad A, Ali MS, Al-Lohadan HA, Atta AM, Khan RH - PLoS ONE (2015)

(A) Far-UV CD spectra of mammalian serum albumins at pH below two unit of proteins pI and (B) at pH above two unit of proteins pI in the absence and presence of rosin surfactant QRMAE. The experiment was performed after 60 min incubation at 65°C. [The presence of secondary structure, contents for α-class of protein was calculated by Chen et al. method that was further supported by K2D software analysis].
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4587963&req=5

pone.0139027.g005: (A) Far-UV CD spectra of mammalian serum albumins at pH below two unit of proteins pI and (B) at pH above two unit of proteins pI in the absence and presence of rosin surfactant QRMAE. The experiment was performed after 60 min incubation at 65°C. [The presence of secondary structure, contents for α-class of protein was calculated by Chen et al. method that was further supported by K2D software analysis].
Mentions: Far-UV CD measurements were used to determine the secondary structure change in the protein. The secondary structure consists of α-helix, β-sheet and random coil structure [29]. Two negative peaks of α-helix lies at 208 nm and 222 nm, one negative peak of β-sheet and one negative peak of random coil lies at 217 nm 197 nm, respectively [41]. Far and near-UV CD studies were used to determine the effect of QRMAE on the secondary and tertiary structure of proteins (albumins) at pH below and above two units of its pI. Proteins were incubated at 65°C for 1 h. It has been shown in Fig 5A that CD spectra of controls and QRMAE induced mammalian serum albumins at pH 3.5 (below two units of pI) exhibited two minima at 208 nm and 222 nm which indicated the formation of α-helical structures [42, 43]. On the other hand, at pH 7.5 (above two units of pI), a noticeable difference in the CD spectra of the albumins (Fig 5B) in the presence of rosin surfactant QRMAE was observed and the data obtained after % α-helisity calculation is listed in Table 1. A remarkable decrease in negative ellipticity of the QRMAE incubated proteins was observed, which indicated that the transformation of α-helical structure to β-sheet or random coil structure occurred due to aggregate formation. This confirmed that the cause of aggregation of albumins was QRMAE at pH two units above its pI and the protein structures still retained their α-helical and radom coil nature.

Bottom Line: It was observed that a suitable molar ratio of protein to QRMAE surfactant enthusiastically induces amorphous aggregate formation at a pH above two units of pI.Rosin surfactant QRMAE-albumins interactions revealed a unique interplay between the initial electrostatic and the subsequent hydrophobic interactions that play an important role towards the formation of hydrophobic interactions-driven amorphous aggregate.Amorphous aggregation of proteins is associated with varying diseases, from the formation of protein wine haze to the expansion of the eye lenses in cataract, during the expression and purification of recombinant proteins.

View Article: PubMed Central - PubMed

Affiliation: Protein Biophysics Laboratory, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh - 202002, India.

ABSTRACT
Quaternary amine of diethylaminoethyl rosin ester (QRMAE), chemically synthesized biocompatible rosin based cationic surfactant, has various biological applications including its use as a food product additive. In this study, we examined the amorphous aggregation behavior of mammalian serum albumins at pH 7.5, i.e., two units above their isoelectric points (pI ~5.5), and the roles played by positive charge and hydrophobicity of exogenously added rosin surfactant QRMAE. The study was carried out on five mammalian serum albumins, using various spectroscopic methods, dye binding assay, circular dichroism and electron microscopy. The thermodynamics of the binding of mammalian serum albumins to cationic rosin modified surfactant were established using isothermal titration calorimetry (ITC). It was observed that a suitable molar ratio of protein to QRMAE surfactant enthusiastically induces amorphous aggregate formation at a pH above two units of pI. Rosin surfactant QRMAE-albumins interactions revealed a unique interplay between the initial electrostatic and the subsequent hydrophobic interactions that play an important role towards the formation of hydrophobic interactions-driven amorphous aggregate. Amorphous aggregation of proteins is associated with varying diseases, from the formation of protein wine haze to the expansion of the eye lenses in cataract, during the expression and purification of recombinant proteins. This study can be used for the design of novel biomolecules or drugs with the ability to neutralize factor(s) responsible for the aggregate formation, in addition to various other industrial applications.

No MeSH data available.


Related in: MedlinePlus