Sucralose Destabilization of Protein Structure

Abstract

Sucralose is a commonly employed artificial sweetener that behaves very differently than its natural disaccharide counterpart, sucrose, in terms of its interaction with biomolecules. The presence of sucralose in solution is found to destabilize the native structure of two model protein systems: the globular protein bovine serum albumin and an enzyme staphylococcal nuclease. The melting temperature of these proteins decreases as a linear function of sucralose concentration. We correlate this destabilization to the increased polarity of the molecule. The strongly polar nature is manifested as a large dielectric friction exerted on the excited-state rotational diffusion of tryptophan using time-resolved fluorescence anisotropy. Tryptophan exhibits rotational diffusion proportional to the measured bulk viscosity for sucrose solutions over a wide range of concentrations, consistent with a Stokes–Einstein model. For sucralose solutions, however, the diffusion is dependent on the concentration, strongly diverging from the viscosity predictions, and results in heterogeneous rotational diffusion.

Retardation of Bulk Water Dynamics by Disaccharide Osmolytes

“…The dependence of the melting temperature as a function of disaccharide concentration has been previously reported for multiple protein models. [6][7][8][9][10]33,37 We verified this trend for both sucrose and trehalose using circular dichroism spectroscopy on a model protein system Staph Nuclease (SN). While both trehalose and sucrose stabilize the native structure of protein against thermal stress, trehalose appears to have a slightly larger slope as a function of increasing concentration; see Figure 1.…”

“…Lifetime measurements were done on a time correlated single photon counting apparatus described in detail elsewhere . In brief, a frequency doubled or tripled output of a high energy oscillator (Coherent Chameleon Ultra II) in conjunction with a pulse selector (Conoptics) was used to provide 425 or 295 nm pulses at 10.6 MHz repetition rate.…”

“…Lifetime measurements were done on a time correlated single photon counting apparatus described in detail elsewhere. 33 In brief, a frequency doubled or tripled output of a high energy oscillator (Coherent Chameleon Ultra II) in conjunction with a pulse selector (Conoptics) was used to provide 425 or 295 nm pulses at 10.6 MHz repetition rate. The light was attenuated (to ∼1.5 mw) and vertically polarized by passing it through a half wave plate and polarizer before exciting the sample in a quartz cuvette of 1 cm path length.…”

Conformational Consequences for Compatible Osmolytes on Thermal Denaturation

“…Lifetime measurements conducted on a time-correlated single photon-counting apparatus described in detail elsewhere [38]. The lifetime of LYen in pure water was measured as 5.9 ± 0.1 ns.…”

“…The measurement of hydration dynamics for LYen is described in detail in Shukla et al [38]. Briefly, a high-energy oscillator (Coherent Chameleon Ultra II, Coherent Inc., Santa Clara, CA, USA) was used as the source of the fundamental beam.…”