First hyperpolarizability of collagen using the point dipole approximation

• The application of localized hyperpolarizabilities to predict a total protein hyperpolariz-ability is presented for the first time, using rat-tail collagen as a demonstration example. Weemploy a model comprising the quadratic Applequist point-dipole approach, the so-calledLoProp transformation and a procedure with molecular fractionation using conjugate capsin order to determine the atomic and bond contributions to the net β tensor of the collagen[(PPG)3 ]10 triple-helix. By using Tholes exponential damping modification to the dyadic ten-sor in the Applequist equations, a correct qualitative agreement with experiment is found. Theintensity of the βHRS signal and the depolarization ratios are best reproduced by decomposingthe LoProp properties into the atomic positions, and using Tholes exponential damping withthe original damping parameter. Some ramifications of the model for general protein propertyoptimization are briefly discussed.

Ämnesord

NATURVETENSKAP  -- Kemi -- Teoretisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Theoretical Chemistry (hsv//eng)

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