Structure of the Protein BPTI Derived with NOESY in Supercooled Water: Validation and Refinement of Solution Structures

Abstract

Fidelity without frostbite: Refinement of an NMR solution structure of 6-kDa protein BPTI determined at 36 °C (see picture, red) with NOE distance constraints measured in supercooled water at −15 °C increased precision of backbone and core side-chain coordinates about twofold (blue). In contrast to cryogenic X-ray crystallography (−150 °C), supercooling to about −15 °C hardly affects the conformation of flexibly disordered surface side chains.