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Biomedical subjects

André Krammer

Publications and source records attributed to André Krammer.

2 recordsLinked to original sources

LigScore: a novel scoring function for predicting binding affinities.

We present two new empirical scoring functions, LigScore1 and LigScore2, that attempt to accurately predict the binding affinity between ligand molecules and their protein receptors. The LigScore functions consist of three distinct terms that describe the van der Waals interaction, the polar attraction between the ligand and protein, and the desolvation penalty attributed to the binding of the polar ligand atoms to the protein and vice versa. Utilizing a regression approach on a data set of 118 protein-ligand complexes we have obtained a linear equation, LigScore2, using these three descriptors. LigScore2 has good predictability with regard to experimental pKi values yielding a correlation coefficient, r2), of 0.75 and a standard deviation of 1.04 over the training data set, which consists of a diverse set of proteins that span more than seven protein families.

Algorithms↗

A structural model for force regulated integrin binding to fibronectin's RGD-synergy site.

The synergy site on fibronectin's FN-III(9) module, located approximately 32 A away from the RGD-loop on FN-III(10), greatly enhances integrin alpha(5)beta(1) mediated cell binding. Since fibronectin is exposed to mechanical forces acting on the extracellular matrix in vivo, we used steered molecular dynamics to study how mechanical stretching of FN-III(9-10) affects the relative distance between these two synergistic sites. Our simulations predict the existence of an intermediate state prior to unfolding. In this state, the synergy-RGD distance is increased from 32 A to approximately 55 A, while the conformations of both sites remain unperturbed. This distance is too large for both sites to co-bind the same receptor, as indicated by experiments that confirm that increasing the length of the linker chain between FN-III(9) and FN-III(10) reduces alpha(5)beta(1) binding. Our simulations thus suggest that increased alpha(5)beta(1)-binding attributed to the synergy site, along with the associated downstream cell-signaling events, can be turned off mechanically by stretching FN-III(9-10) into this intermediate state. The potential physiological implications are discussed.

Computer Simulation↗