... N-terminal hairpin and an anti-parallel b-sheet, with a characteris-tic a + b fold and a highly positive charged surface. Compared to itslarger homolog a- sarcin, the N-terminal hairpin is shorter and ... inHtA replaces a tyrosine of a- sarcin, and the aromaticring of F126, close to the catalytic H113, replaces a leucine side chain in a- sarcin in a similar arrangementto that found in RNase T1. ... JM, Davies J, Martı´nez delPozo A & Gavilanes JG (2001) RNase U2 and alpha-sarcin: a study of relationships. Meth Enzymol 341,335–351.3 Lacadena J, A ´lvarez-Garcı´ a E, Carreras-Sangra...