The ELLIPS suite of macromolecular conformation algorithms

Area of Science:

• Biophysics
• Physical Chemistry
• Computational Biology

Background:

• Accurate determination of macromolecular shape in solution is crucial for understanding biological function.
• Existing methods often rely on simplified models or require assumptions about hydration.
• Hydrodynamic measurements provide valuable data for inferring molecular dimensions and shape.

Purpose of the Study:

• To present a suite of four PC-based programs (ELLIPS1-4) for analyzing macromolecular shape.
• To utilize ellipsoidal representations and Universal shape functions for shape determination.
• To enable calculation of axial ratios and molecular dimensions from diverse hydrodynamic data.

Main Methods:

• ELLIPS1: Models macromolecules as ellipsoids of revolution, calculating axial ratios from hydrodynamic shape functions.
• ELLIPS2: Utilizes triaxial ellipsoids, calculating all hydrodynamic shape functions from user-inputted dimensions or axial ratios.
• ELLIPS3 & ELLIPS4: Reverse ELLIPS2, uniquely determining triaxial dimensions or axial ratios from multiple hydrodynamic measurements (e.g., intrinsic viscosity, radius of gyration, sedimentation coefficients, rotational relaxation times, electro-optic decay).

Main Results:

• The ELLIPS programs provide versatile tools for macromolecular shape analysis.
• ELLIPS1 and ELLIPS2 allow forward calculation of shape parameters based on ellipsoidal models.
• ELLIPS3 and ELLIPS4 enable inverse calculation of molecular dimensions from experimental hydrodynamic data without prior hydration assumptions.

Conclusions:

• This software suite offers a comprehensive approach to characterizing macromolecular shape in solution.
• The programs facilitate the interpretation of various hydrodynamic measurements for structural elucidation.
• These computational tools enhance the ability to determine detailed molecular geometries from experimental data.