bacteriochlorophyll

Any of the forms of chlorophyll found in photosynthetic bacteria. Bacteriochlorophyll a, found in all bacteria, differs from the chlorophyll of plants in being a tetrahydroporphyrin rather than a dihydroporphyrin (i.e. it has more hydrogen atoms in pyrrole rings 2 and 4 of the chlorophyll molecule). It also differs in its absorption spectrum having three peaks, at 365, 605, and 770 nm. Some bacteria contain additional forms of bacteriochlorophyll (Bchl) designated Bchl b, Bchl c, and Bchl d.