Recent structure analyses of alpha B-crystallin have proposed some models of the N-terminal domain and the manner of oligomerization, whereas the effects of the significantly high content of Pro residues at the N-terminal domain remain unclear. We report the properties of a novel P39R mutant of alpha B-crystallin. The content of alpha-helix was increased, and the molecular size of the P39R mutant was larger than that of wild-type alpha B-crystallin. A slight loss of chaperone-like activity was observed using alcohol dehydrogenase (ADH), while a significant increase was detected by insulin assay. The Pro residue at the N-terminal domain of alpha B-crystallin is important for oligomerization and function. (C) 2012 Elsevier Inc. All rights reserved.