Sandbox 179: Difference between revisions
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One of the main salt bridges in pepsin includes residues from one of the dyad-related hylices (h’N and h’C) and a residue from the opposite lobe, e.g. Asp138 interacts with Arg316. For an image of these residues refer to image 1. bellow. This ion-pair may be important for the stability of the pepsin fold, since chemical modification of Arg316 with butane-2,3-dione partially inactivates the enzyme, as does treatment with phenylglyoxal <ref name="Xray" />. | One of the main salt bridges in pepsin includes residues from one of the dyad-related hylices (h’N and h’C) and a residue from the opposite lobe, e.g. Asp138 interacts with Arg316. For an image of these residues refer to image 1. bellow. This ion-pair may be important for the stability of the pepsin fold, since chemical modification of Arg316 with butane-2,3-dione partially inactivates the enzyme, as does treatment with phenylglyoxal <ref name="Xray" />. | ||
Image 1. The hydrogen bonds between Asp138 and Arg316[[Image:Hydrogen bond.png|450 px ]] | |||
There are many sub domains in pepsin. One sub domain which includes the residues 222-235; 255-276; and 283-290. Portions of this sub domains can interact with inhibitors, and therefore contribute to the structural delineation of S’ sub sites <ref name="flexible" />. It is also possible that ridged movements of sub domains relative to the large domain may help the enzyme adjust to various substrate structures. Furthermore, local regional flexibility of structures such as the “flap,” in and around the active site of pepsin has been suggested to modulate substrate and inhibitor binding <ref name="flexible" />. | There are many sub domains in pepsin. One sub domain which includes the residues 222-235; 255-276; and 283-290. Portions of this sub domains can interact with inhibitors, and therefore contribute to the structural delineation of S’ sub sites <ref name="flexible" />. It is also possible that ridged movements of sub domains relative to the large domain may help the enzyme adjust to various substrate structures. Furthermore, local regional flexibility of structures such as the “flap,” in and around the active site of pepsin has been suggested to modulate substrate and inhibitor binding <ref name="flexible" />. | ||
