Many toxin-antitoxin (TA) loci are known to strongly repress their own transcription. This auto-inhibition is often called 'conditional cooperativity' as it relies on cooperative binding of TA complexes to operator DNA that occurs only when toxins are in a proper stoichiometric relationship with antitoxins. There has recently been an explosion of interest in TA systems due to their role in bact...

Experiments point to appreciable variations in folding cooperativity among natural proteins with approximately 40 residues, indicating that the behaviors of these proteins are valuable for delineating the contributing factors to cooperative folding. To explore the role of native topology in a protein's propensity to fold cooperatively and how native topology might constrain the degree of cooper...

Equilibrium binding studies show that 6 atoms of calcium are bound by the dimeric molecule of the sarcoplasmic calcium-binding protein (SCP) from crayfish. SCP exhibits positive cooperativity in calcium-binding for four sites, as indicated by increasing intrinsic binding constants (1 to 5 x 10” M-l), and negative cooperativity for the other two sites (decreasing constants from 5 to 0.8 x lo7 M-...

Cat hemoglobin has been found to exist in three forms which differ in the cooperativity of oxygen binding at low and high pH values. Type I cat hemoglobin has a high cooperativity (n = 2.7 to 3.1) at both high (pH = 7.8 to 9.0) and low (pH = 6.5 to 6.9) pH values. Type II hemoglobin exhibits low cooperativity (n = 1.8 to 2.3) in the low pH range but high cooperativity in the high pH range. Type...

Enhanced surfactant association by solutes drives cooperative solubilization according to the universal statistical thermodynamic theory.

We show that the cooperative reinforcement between hydrogen bonds in guanine quartets is not caused by resonance-assisted hydrogen bonding (RAHB). This follows from extensive computational analyses of guanine quartets (G(4)) and xanthine quartets (X(4)) based on dispersion-corrected density functional theory (DFT-D). Our investigations cover the situation of quartets in the gas phase, in aqueou...

We use a tetrahedral model of four interacting protein subunits to represent the K(+) channel or gate in the squid nerve membrane. The kinetic predictions, with varying degrees of cooperativity, are compared with experimental observations, especially those of Hodgkin and Huxley (J. Physiol. 117, 500, 1952) and of Cole and Moore (Biophys. J. 1, 1, 1960). The tentative conclusion reached is that ...

Studying the interplay between multiple coupled mechanical resonators is a promising new direction in field of optomechanics. Understanding dynamics interaction can lead to rich effects, such as enhanced coupling and multi-body physics. In particular, multi-resonator optomechanical systems allow for distinct dynamical effects due optical cavity coherently resonators. Here, we study response two...

Chaperonins mediate protein folding in an ATP-dependent manner. ATP binding and hydrolysis by chaperonins are subject to both homotropic and heterotropic allosteric regulation. In the case of GroEL and CCT, homotropic regulation by ATP is manifested in nested cooperativity, which involves positive intra-ring cooperativity and negative inter-ring cooperativity in ATP binding. Both types of coope...