In enzymology, a 2,1-fructan:2,1-fructan 1-fructosyltransferase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are <code>[beta-D-fructosyl-(2->1)-m]]</code> and <code>beta-D-fructosyl-(2->1)-n]]</code>, whereas its two products are <code>beta-D-fructosyl-(2->1)-m-1]]</code> and <code>beta-D-fructosyl-(2->1)-n+1]]</code>.
This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is 2,1-beta-D-fructan:2,1-beta-D-fructan 1-beta-D-fructosyltransferase. Other names in common use include 1,2-beta-D-fructan 1F-fructosyltransferase, fructan:fructan fructosyl transferase, FFT, 1,2-beta-fructan 1F-fructosyltransferase, 1,2-beta-D-fructan:1,2-beta-D-fructan, 1F-beta-D-fructosyltransferase, and fructan:fructan 1-fructosyl transferase.