Unraveling Polymorphism and Twisting in Near-Perfect Protein Crystals

Area of Science:

• Crystallography
• Materials Science
• Biophysics

Background:

• Crystals typically exhibit well-defined shapes and periodic atomic/molecular arrangements.
• Crystal twisting is an unusual morphology, creating a paradox with crystalline order.
• The causes of spontaneous twisting in crystals lacking long-range order are not fully understood.

Purpose of the Study:

• To demonstrate control over crystal twisting and perfection using macromolecular crystal polymorphs.
• To elucidate the mechanisms underlying spontaneous crystal twisting.
• To investigate the relationship between crystal morphology and molecular interactions.

Main Methods:

• Utilized macromolecular crystal polymorphs to induce and control twisting.
• Analyzed anisotropic interactions, specifically salt bridges between protein molecules.
• Applied dynamical theory of X-ray diffraction to study crystal structure and imperfections.

Main Results:

• Demonstrated that crystal polymorphs can control either perfect crystalline structures or twisting.
• Established a link between anisotropic interactions (salt bridges) and the observed morphology.
• Identified twisting as a unique imperfection, distinct from conventional crystal defects.

Conclusions:

• Crystal twisting in macromolecular crystals is governed by polymorphs and anisotropic interactions.
• Salt bridges play a crucial role in determining crystalline order versus twisting.
• Twisting is a novel type of crystal imperfection, offering new avenues for controlling crystal perfection.