Anisotropic behaviour of the C-terminal Kunitz-type domain of the α3 chain of human type VI collagen at atomic resolution (0.9 Å)

The C-terminal Kunitz-type domain from the α3 chain of human type VI collagen (C5), a single amino-acid residue chain with three disulfide bridges, was refined at 0.9 Å resolution in a monoclinic form, space group P2₁ with one molecule per asymmetric unit, using data collected at cryogenic temperature (110 K). The average protein 〈B〉 factor decreases from 21 Ų at room temperature (RT) to 12 Ų at cryotemperature (100 K, CT). The spatially close N- and C-termini remain highly disordered. The different structural motifs of C5 were analyzed in terms of rigid-body displacement (TLS analyses) and show dominant libration motion for the secondary structure.