Photochromic chromopeptides derived from phycoerythrocyanin: biophysical and biochemical characterization.
Truncated chromopeptides have been prepared from the small photo- and redox-switchable biliprotein alpha-phycoerythrocyanin (alpha-PEC). The native chromoprotein consists of a C-terminal globin domain containing the chromophore and the regulatory cysteins 98 and 99, and a two-helix (X,Y) N-terminal domain responsible for aggregation. Digestion with chymotrypsin-free trypsin leads to three chromopeptides, (N-30, N-33 and N-35), basically lacking the two N-terminal helices X and Y. The photo- and redox chemistry of the major product (N-33) is identical, qualitatively and quantitatively, to that of native alpha-PEC. A series of N- and C-terminally truncated polypeptides were expressed in E. coli and subjected to autocatalytic and enzymatic reconstitution with phycocyanobilin. Enzymatic reconstitution was possible with N-terminally truncated polypeptides up to 45 aa, while neither a more extensively shortened (N-63) peptide, nor two C-terminally shortened polypeptides could be reconstituted. All chromopeptides recovered from enzymatic reconstitution contained the native phycoviolobilin chromophore and showed the photochemical and redox reactivity of alpha-PEC, albeit quantitatively reduced in the N-45 chromopeptide.
Zhao
Kai-Hong
KH
College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, Hubei, P.R. China.
Zhu
Jing-Ping
JP
Deng
Ming-Gang
MG
Zhou
Ming
M
Storf
Max
M
Parbel
Axel
A
Scheer
Hugo
H
D003001:Cloning, Molecular; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D010777:Photochemistry; D052980:Phycobilins; D010798:Phycocyanin / Q000737:chemistry* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011758:Pyrroles; D045725:Tetrapyrroles; D014357:Trypsin / Q000378:metabolism
D010446:Peptide Fragments; D052980:Phycobilins; D011758:Pyrroles; D045725:Tetrapyrroles; C038397:phycoerythrocyanin; D010798:Phycocyanin; C011069:phycocyanobilin; D014357:Trypsin