title: Conformational transitions of cinnamoyl CoA reductase 1 from Leucaena leucocephala.
abstract: Conformational transitions of cinnamoyl CoA reductase, a key regulatory enzyme in lignin biosynthesis, from Leucaena leucocephala (Ll-CCRH1) were studied using fluorescence and circular dichroism spectroscopy. The native protein possesses four trp residues exposed on the surface and 66% of helical structure, undergoes rapid structural transitions at and above 45 °C and starts forming aggregates at 55 °C. Ll-CCRH1 was transformed into acid induced (pH 2.0) molten globule like structure, exhibiting altered secondary structure, diminished tertiary structure and exposed hydrophobic residues. The molten globule like structure was examined for the thermal and chemical stability. The altered secondary structure of L1-CCRH1 at pH 2.0 was stable up to 90 °C. Also, in presence of 0.25 M guanidine hydrochloride (GdnHCl), it got transformed into different structure which was stable in the vicinity of 2M GdnHCl (as compared to drastic loss of native structure in 2M GdnHCl) as seen in far UV-CD spectra. The structural transition of Ll-CCRH1 at pH 2.0 followed another transition after readjusting the pH to 8.0, forming a structure with hardly any similarity to that of native protein.
authors.affiliation: Plant Tissue Culture Division, CSIR-National Chemical Laboratory, Pune 411008, India.
authors.forename: Prashant D
authors.initials: PD
authors.lastname: Sonawane
authors.affiliation: Plant Tissue Culture Division, CSIR-National Chemical Laboratory, Pune 411008, India.
authors.forename: Bashir M
authors.initials: BM
authors.lastname: Khan
authors.affiliation: Division of Biochemical Sciences, CSIR-National Chemical Laboratory, Pune 411008, India. Electronic address: sm.gaikwad@ncl.res.in.
authors.forename: Sushama M
authors.initials: SM
authors.lastname: Gaikwad
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000737:chemistry*; D002942:Circular Dichroism; D007887:Fabaceae / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding
chemical_list: D000445:Aldehyde Oxidoreductases; C019904:cinnamoyl CoA reductase
keywords: Aggregation; Cinnamoyl CoA reductase; Conformation; Molten globule; Thermostability; Unfolding