User:Andelgado223/Stellacyanin

Stellacyanin is a protein specific to plants that contains a singular copper ion bound in a blue configuration (type 1). Stellacyanin’s spectroscopic properties help us differentiate it from plastocyanin, which is another monocopper blue protein found in plants.

Stellacyanins are characterized by their uniquely low redox potentials, as low as +180 mv and reach up to 280 mV. Other blue copper protein redox potentials start around 310 mV and reach up to  680 mV.

A mutant cucumber stellacyanin was created by replacing the glutamine axial ligand (a ligand which all other blue proteins contain) with a methionine (Q99M) and purified. The spectroscopic properties found were common to uclacyanin- not plantacyanins. Stellacyanin with the substation of the axial G redox potential was calculated to be +420 mV, which much higher than the redox potential of the stellacyanin found in nature (without methionine) at +260 mV. Structural design also poses the question if stellacyanins may possibly not be diffusible electron transfer proteins in long range electron-transfering. Stellacyanins are most involved in redox reactions of plants that take place during a defense response, and formation of lignin.

Stellacyanins are also distinguishable from plantacyanins and other cupredoxins by the structure if their amino acid residue position relative to the pivotal site of copper.