Ultrafast Structural Changes Decomposed from Serial Crystallographic Data.

Area of Science:

• Biochemistry
• Structural Biology
• Physical Chemistry

Background:

• Understanding biochemical reaction mechanisms requires direct visualization of electronic and molecular events.
• Ligand photodissociation in proteins like myoglobin is a key process studied via spectroscopy and simulations.

Purpose of the Study:

• To analyze serial crystallographic data of carbonmonoxy myoglobin after photolysis.
• To visualize and understand the dynamic electronic and molecular changes in the first picoseconds.
• To validate previous experimental and simulation findings with direct electron density data.

Main Methods:

• In-depth analysis of serial crystallographic datasets.
• Detection and isolation of transient electronic changes using advanced analytical methods.
• Focus on electron density variations in the heme iron and surrounding solvent.

Main Results:

• Revealed electron density changes linked to high-spin 3d atomic orbitals of heme iron upon photolysis.
• Observed dynamic behavior of heme iron, including popping out and recoiling into the heme plane within picoseconds.
• Identified significant electron density variations in the solvent during early stages of low-frequency oscillation.

Conclusions:

• Provides direct visual evidence validating ultrafast spectroscopy and molecular dynamics simulations of photodissociation.
• Highlights the capability of analytical methods to detect subtle, transient electronic signals in chemical reactions.
• Offers mechanistic insights into the dynamics of heme iron and solvent interactions post-photolysis.