In:
Photochemistry and Photobiology, Wiley, Vol. 85, No. 5 ( 2009-09), p. 1140-1146
Abstract:
Demetalation kinetics of bacteriochlorophylls (BChls) c, d and e from green sulfur photosynthetic bacteria were studied under weakly acidic conditions. Demetalation rate constants of BChl e possessing a formyl group at the 7‐position were significantly smaller than those of BChls c and d , which had a methyl group at this position. The activation energy of demetalation of 3 1 R ‐8,12‐diethyl([E,E])‐BChl e was 1.5‐times larger than that of 3 1 R ‐[E,E]‐BChl c . 15 N‐labeled 3 1 R ‐[E,E]‐BChls c and e were purified from cells of green sulfur bacteria grown in a medium containing 15 NH 4 Cl, and their 15 N NMR spectra were measured. The chemical shifts of N 21 , N 22 and N 23 atoms of 3 1 R ‐[E,E]‐BChl e were lower‐field shifted than those of 3 1 R ‐[E,E]‐BChl c , respectively, and especially the difference in chemical shifts of N 22 was significantly large. These results suggest that the electron‐withdrawing formyl group at the 7‐position of BChl e affected an electronic state of the chlorin macrocycle and caused BChl e to be more tolerant for removal of the central magnesium compared with BChls c and d .
Type of Medium:
Online Resource
ISSN:
0031-8655
,
1751-1097
DOI:
10.1111/php.2009.85.issue-5
DOI:
10.1111/j.1751-1097.2009.00580.x
Language:
English
Publisher:
Wiley
Publication Date:
2009
detail.hit.zdb_id:
2048860-9
SSG:
12
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