322 / Biochemistry electrostatic charges

Lee K, Fitch CA, Lecomte JT, Garcfa-Moreno EB (2002) Electrostatic effects in highly charged proteins Salt sensitivity of pKa values of histidines in staphylococcal nuclease. Biochemistry 41 5656-5667. 

Stauffer, D.A., and Karlin, A. (1994) Electrostatic potential of the acetylcholine binding sites in the nicotinic receptor probed by reaction of binding-site cysteines with charged methanethiosulfonates. Biochemistry 33, 6840-6849. 

Fig. Z14. The activation of chymotrypsin via proteolytic cleavage, a) Chymotrypsinogen is transformed into the active forms of chymotrypsin n and a by trypsin and autoproteolysis, b) The N-terminal isoleucine residue Ile6 is particularly important for the activity of chymotrypsin. The positively charge NH2 group of llel6 interacts electrostatically with Aspl94 and stabilizes an active conformation of the catalytic center. After Stryer Biochemistry , with permission.

Callender, Biochemistry 13, 4243 (1974). Each pigment has unique physiochemical properties. The most significant is the absorption spectrum which is regulated by electrostatic interactions between the chromophore and the charged or dipolar groups on the opsin R. Hubbard, L. Sparling, Exp. Eye Res. 17, 581 (1973) B. Honig et al, J. Am, Chem. Soc. 101, 7084 (1979). 

Schwehm, J.M., Fitch, C.A., Dang, B.N., Garcia-Moreno, E.B., Stites, WE. Ghanges in stability upon charge reversal and neutralization substitution in staphylococcal nuclease are dominated by favorable electrostatic effects. Biochemistry 2003, 42,1118-28. 

All science is based on a number of axioms (postulates). Quantum mechanics is based on a system of axioms that have been formulated to be as simple as possible and yet reproduce experimental results. Axioms are not supposed to be proved, their justification is efficiency. Quantum mechanics, the foundations of which date from 1925-26, still represents the basic theory of phenomena within atoms and molecules. This is the domain of chemistry, biochemistry, and atomic and nuclear physics. Further progress (quantum electrodynamics, quantum field theory, elementary particle theory) permitted deeper insights into the structure of the atomic nucleus, but did not produce any fundamental revision of our understanding of atoms and molecules. Matter as described at a non-relativistic quantum mechanics represents a system of electrons and nuclei, treated as point-like particles with a definite mass and electric charge, moving in three-dimensional space and interacting by electrostatic forces. This model of matter is at the core of quantum chemistry. Fig. 1.2. 

J. J. Sines, S. A. Allison, and J. A. McCammon, Biochemistry, 29,9403 (1990). Point Charge Distributions and Electrostatic Steering in Enzyme/Substrate Encounter Brownian Dynamics of Modified Copper/Zinc Superoxide Dismutase. 

With the anionic genetic materials, these vectors form polyelectrolyte complexes, sometimes endowed with modest positive charge, that greatly reduce the enzymatic degradation of the genetic materials and are often readily taken up by cells. The biochemistry of the cellular uptake of such complexes is probably mediated by the electrostatic interaction of the nanocomplex with the anionic cellular membrane (Mounkes et al., 1998). Once inside the cell the complex unwinds, setting the genetic material free to execute its function. 

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