The Light-Dependent and Light-Independent Reduction of Protochlorophyllide a to Chlorophyllide a

As it is known, a key reaction in the production of chlorophyll requires a reductase. This can be done in two ways; via a light reaction and a non-light reaction. This paper discusses the mechanism of these reactions and what molecules are involved in the reaction.


 http://www.springerlink.com/content/v82wn141907l5075/

A Prokaryotic Origin for Light-Dependent Chlorophyll Biosynthesis of Plants

The reduction of protochlorophyllide is important because it allows for the performance of photosynthesis by plants. This is catalyzed by either light dependent protochlorophyllide, found in angiosperms, or light-independent protochlorophyllide, found in gymnosperms, bacterium, etc. It has been found, however, that both of these enzymes are found in some bacteria, such as Synechocystis. It was found that the bacteria could produce chlorophyll in the light and that protochlorophyllide built up when in the dark, leading to the conclusion that the light-dependent version evolved not as a necessary function of land plants but as an accessory of bacteria.



http://www.jstor.org/stable/2367424?seq=1&Search=yes&searchText=reductase&searchText=protochlorophyllide&list=hide&searchUri=%2Faction%2FdoBasicSearch%3FQuery%3Dprotochlorophyllide%2Breductase%26acc%3Don%26wc%3Don&prevSearch=&item=1&ttl=269&returnArticleService=showFullText&resultsServiceName=null

Yellow-in-the-Dark Mutants of Chlamydomonas Lack the CHLL Subunit of Light-Independent Protochlorophyllide Reductase

A key step in the production of chlorophyll is the reduction of a double bond of an intermediate structure. This can be done by one of two ways; with light in angiosperms or without light in gymnosperms, cyanobacteria, etc. With light, the reaction can occur via a reductase. However, without light, the reaction requires the use of certain genes. In the bacteria Chlamydomonas reinhardtii, the genes ChlL, ChlN and ChlB and certain loci, y, must be present. The products of these genes are thought to be subunits of the enzyme Light-Independent Protochlorophyllide Reductase, which catalyzes the reduction of the double bond mentioned earlier. When reacted with light, it was found that the ChlL protein was inhibited. Also, the y genes were required for the production of the ChlL protein.

Protein view 5