Aqueous Liquid-Liquid Phase Separation of Natural and Synthetic Polyguanidiniums.

ABSTRACT: Protamines are natural polyguanidiniums, arginine(R)-rich proteins involved in the compaction of chromatin during vertebrate spermatogenesis. Salmine, a protamine isolated from salmon sperm, contains 65 mol% R residues, with positively charged guanidino (Gdm⁺) sidechains, and no other amino acids with ionizable or aromatic sidechains. Salmine sulfate solutions undergo liquid-liquid phase separation (LLPS) with a concentration-dependent upper critical solution temperature (UCST). The condensed liquid phase comprises 50 wt % water and >600 mg·ml^-¹ salmine with a constant 1:2 ratio of sulfate (SO₄²^-) to Gdm⁺. Isothermal titration calorimetry, titrating Na₂SO₄ into salmine chloride above and below the UCST, allowed isolation of exothermic sulfate binding to salmine chlori

SUBMITTER: Prather LJ 

PROVIDER: S-EPMC6523547 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature