The Conformation of Bilin Chromophores in Biliproteins: Ramachandran-Type Calculations

نویسندگان

  • Hugo Scheer
  • Helmut Formanek
چکیده

Bilin Conformation, Phycocyanin, Phycoerythrin, Phytochrome Ramachandran-type calculations are performed for conformations of bilin chromophores pres­ ent in the biliproteins phycocyanin, phycoerythrin and phytochrome. The atomic coordinates are taken from x-ray data of crystalline model compounds, namely biliverdin for pyrrole rings B, C, D and substituted succinimides for the hydrogenated ring A including a thioether containing ^-sub­ stituent. Maxima and minima for steric hindrance are calculated for rotation of the thioether side chain, the rotation of pyrrole rings at single bonds (syn-anti-forms) and at double bonds (Z-E-isomers) of the methine bridges. Whereas quasi-planar structures are possible for all syn, Z-forms, only twisted structures are possible if anti, E-forms are considered. The relevance for the bilin con­ formations of native biliproteins and of the Pr ^ Pfr phototransformation is discussed.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Phycobilins of cryptophycean algae. Occurrence of dihydrobiliverdin and mesobiliverdin in cryptomonad biliproteins.

Structures of the open-chain tetrapyrrole (bilin) prosthetic groups of the cryptophycean biliproteins phycocyanin 645 (Cr-PC 645; from strain UW374), phycoerythrin 566 (Cr-PE 566; from strain Bermani) and phycoerythrin 545 (Cr-PE 545; from Proteomonas sulcata Hill & Wetherbee) were examined by absorption, 1H NMR spectroscopy, and mass spectrometry. These biliproteins carry the following covalen...

متن کامل

Dissociating effect of chromophore modifications C-phycocyanin heterohexamers on

The bilin chromophores of the a or /3 subunit of C-phycocyanin (PC) from Mastigocladus laminosus were modified, and subsequently recombined with the respective complementary unmodified chromophores. The modifications consisted of photobleaching (350 nm) or reversible reduction of the verdinto rubin-type chromophore(s). Recombination led to heterodimers (a& but the heterohexameric aggregation st...

متن کامل

Conformational Studies of Biliproteins from the Insects Pieris brassicae and Cerura vinula

Chromophore conformation and protein secondary structure of biliproteins from the butterfly, Pieris brassicae, and the moth, Cerura vinula, have been investigated by absorption, circular dichroism and fluorescence spectroscopy. The chromophore of the P. brassicae protein, biliverdin IXy, has probably a cyclic-helical structure similar to that of free bile pigments of the biliverdin type. Though...

متن کامل

Conformational analysis of N- and C-terminally protected tripeptide model glycyl-isoleucine-glycyl: An ab initio and DFT study

An ab initio and density functional theory (DFT) study about conformational analysis of tripeptide model HCO−GLY−L−ILE−GLY−NH2 is presented. The tripeptide was scanned about initial, central, and final residues, separately while for every scanning procedure the two other residues had been kept in the β conformation and side chain (SC) dihedral angles were maintained on the gauche− (g‾) state (χ...

متن کامل

Theoretical studies of biliprotein chromophores and related Bile pigments by molecular orbital and ramachandran type calculations.

Ramachandran calculations have been used to gain insight into steric hindrance in bile pigments related to biliprotein chromophores. The high optical activity of denatured phycocyanin, as compared to phycoerythrin, has been related to the asymmetric substitution at ring A, which shifts the equilibrium towards the P-helical form of the chromophore. Geometric effects on the electronic structures ...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2013