902268-70-6Relevant articles and documents
Biliverdin amides reveal roles for propionate side chains in bilin reductase recognition and in holophytochrome assembly and photoconversion
Shang, Lixia,Rockwell, Nathan C.,Martin, Shelley S.,Lagarias, J. Clark
, p. 6070 - 6082 (2010)
Linear tetrapyrroles (bilins) perform important antioxidant and light-harvesting functions in cells from bacteria to humans. To explore the role of the propionate moieties in bilin metabolism, we report the semisynthesis of mono- and diamides of biliverdin IXα and those of its non-natural XIIIα isomer. Initially, these were examined as substrates of two types of NADPH-dependent biliverdin reductase, BVR and BvdR, and of the representative ferredoxin-dependent bilin reductase, phycocyanobilin:ferredoxin oxidoreductase (PcyA). Our studies indicate that the NADPH-dependent biliverdin reductases are less accommodating to amidation of the propionic acid side chains of biliverdin IXα than PcyA, which does not require free carboxylic acid side chains to yield its phytobilin product, phycocyanobilin. Bilin amides were also assembled with BV-type and phytobilin-type apophytochromes, demonstrating a role for the 8-propionate in the formation of the spectroscopically native Pr dark states of these biliprotein photosensors. Neither ionizable propionate side chain proved to be essential to primary photoisomerization for both classes of phytochromes, but an unsubstituted 12-propionate was required for full photointerconversion of phytobilin-type phytochrome Cph1. Taken together, these studies provide insight into the roles of the ionizable propionate side chains in substrate discrimination by two bilin reductase families while further underscoring the mechanistic differences between the photoconversions of BV-type and phytobilin-type phytochromes.
ADDITION OF 2-MERCAPTOPROPIONYLGLYCINE TO BILIVERDIN: A KINETIC AND THERMODYNAMIC STUDY
Beltrame, Pier Luigi,Monti, Diego,Sala, Roberto,Manitto, Paolo
, p. 223 - 226 (2007/10/02)
The reaction between biliverdin and 2-mercaptopropionylglycine was studied at 27.5 deg C in DMSO and in aqueous buffer solution (pH 7.4).In the latter medium, the thiol was added to biliverdin either alone or associated with human serum albumin.The equilibrium constants of the reaction carried out in DMSO and in aqueous solution with and without albumin were found to be 40.6E2, 69.2E2, and 1.20E2 M-1, respectively.The kinetics of the reaction carried out in aqueous medium were determined.The results are discussed as a possible model for the photochromic plant photoreceptor phytochrome.
