Title

Crystal and Molecular Structure of Methyl Bacteriopheophorbide a. A Model for a Primary Electron Acceptor in Bacterial Photosynthesis

Document Type

Article

Publication Date

1-1-1981

Abstract

Bacteriopheophytin is a key component in the mechanism by which photosynthetic bacteria transduce solar energy into chemical form. The structure of methyl bacteriopheophorbide a, a bacteriopheophytin derivative, has been determined by three-dimensional X-ray diffraction. The compound crystallizes in space group PI in a unit cell containing a molecule of methyl bacteriopheophorbide and a benzene molecule of crystallization, with lattice constants a = 7.2502 (8) Å, b = 8.1070 (9) Å, c = 17.224 (5) Å, α = 90.80 (2)°, β = 94.17 (2)°, and 7 = 110.38 (1)°. The structure has been refined with isotropic thermal parameters on F by full-matrix least squares to RF = 0.110, based on 860 reflections. The molecules associate in chains via π-π interactions with ring I of one molecule overlapping ring III of its neighbor with a vertical separation of 3.6 Å. The one-dimensional chains form two-dimensional layers without the intervention of the hydrogen bonding by water molecules previously reported for chlorophyllides. This work represents the first crystallographic determination of a bacteriochlorin and confirms the canonical structures and relative orientations of the five chiral centers of bacteriochlorophyll a derivatives. © 1981, American Chemical Society. All rights reserved.

Publication Source (Journal or Book title)

Journal of the American Chemical Society

First Page

5890

Last Page

5893

This document is currently not available here.

Share

COinS