with these denotation, each of which contain cysteine number 256 which is important in APS initiated analysis although traditionally considered disordered within the context of the adenylyl sulfate-reductase structure. Species distribution Many organisms use this enzyme, primarily plants as mentioned and many microorganisms such as E. coli and fungal plant rhizobia. E. coli is experimentally found to harness this enzyme with variants associated with serine and cysteine residues and is inherently involved within its own intermediate and its stabilization with the up-taking of the adenylyl sulfate-reductase and thioredoxin produced by P. aeruginosa. This enzyme is also found in several forms of mycobacteria and other fungi including, as mentioned, rhizobia. Rhizobia use the same pathway but some such as Rhizobium meliloti have a limited genetic scope that would result in adenylyl-sulfate reductase production with the genes only appearing on a few loci, but is used in primarily the same way as in bacterial organisms for the production of a small selection of amino acids. Function The structure of adenylyl sulfate-reductase (thioredoxin) has been experimentally shown to follow an open-close system during the reaction when binding the substrate into the active site cleft. When the thioredoxin is detected by the enzyme, the C-terminal tail moves over the active site and forms a closed position within the enzyme itself, allowing for the cysteines that are catalytically necessary to move in and make sufficient contact with the thioredoxin. This action only occurs upon substrate binding. It's important to note that further research still is being completed onto the conformational shifts during the reduction reaction upon thioredoxin binding. However, it is suggested that other conformational steps are needed in order for the intermediate to complete binding to the thioredoxin. These evidence-based speculations consider the evolution of other bacteria that may have reacted with this enzyme or another metabolite over time. In unicellular organisms such as mycobacteria, one use of this enzyme is in the production of certain proteins, primarily types that either involve or lead to the eventual amino acids cysteine and then methionine. The thioredoxin dependent adenylyl-sulfate reductase's cleaved disulfuric ions are incorporated into the molecular structure of the proto-proteins in the formation of the aforementioned amino acids. In studies such as one published in the Journal of Biological Chemistry experimentally observed the use of this enzyme type and thioredoxin in the synthesis of the above mentioned proteins within mycobacteria. The working pathway that