Question

Bacterio-chlorophyll a is represented as
A) ${C_{55}}{H_{74}}{O_6}{N_4}Mg$
B) ${C_{55}}{H_{70}}{O_6}{N_4}Mg$
C) ${C_{55}}{H_{72}}{O_5}{N_4}Mg$
D) ${C_{35}}{H_{32}}{O_5}{N_4}Mg$

Answer 1

Bacterio-chlorophyll (BChI) is the photosynthetic pigments which were discovered by C.B. van Niel. They occur in various phototrophic bacteria.

Complete answer:

Pigment	Bacterial group
Bacteriochlorophyll a	Green sulfur bacteria, purple bacteria, helicobacter,chloroflexi, chloracidobacterium thermophilum.
Molecular formula	${C_{55}}{H_{74}}{O_6}{N_4}Mg$
Molecular weight	$911\,g/mol$

Bacteriochlorophylls a, b, and g are the bacteriochlorins macrocycle ring containing two reduced pyrrole rings.
Bacteriochlorophylls c, d, e and f are chlorins whose molecules have a chlorine macrocycle ring and one reduced pyrrole ring.
Bacteriochlorophylls c to f are closely related homologs and contain different alkyl groups and are attached to pyrrole rings.
Bacteriochlorophylls g contains vinyl groups.
Chlorophyllide andChlorophyllide b are precursors of chlorophyll a and chlorophyll b. Their propionic acid groups are converted by chlorophyll synthase enzyme to phytyl esters.
Chlorophyll Idea is also used as an intermediate in the biosynthesis of bacteriochlorophyll.
In the biosynthesis, the first step is reduction of the pyrrole ring (18-electron aromatic system) of various bacteriochlorophylls.
This reaction is carried out by enzyme chlorophyllide, a reductase.
Chlorophyllide$a + 2$reduced ferredoxin $+ ATP + {H_2}0 + 2{H^ + }$→ 3-deacetyl 3- vinyl bacteriochlorophyll ide$a + 2$oxidized ferredoxin + ADP + phosphate
In the next steps the vinyl group first converts into 1-hydroxyethyl group and then into acetyl group of bacteria chlorophyllide a. This is catalyzed by bacteriochlorophyll ide, a dehydrogenase.

The correct answer is ${C_{55}}{H_{74}}{O_6}{N_4}Mg$.

Note: Those organisms that consist of bacteriochlorophyll conduct photosynthesis for their energy requirement but they don’t produce oxygen as a side product.