... Destabilization of psychrotrophic RNase HI in a localized fashion as revealed by mutational and X-ray crystallographic analyses Muhammad S. Rohman1, Takashi Tadokoro1, Clement Angkawidjaja1, Yumi Abe1,Hiroyoshi ... Gly and Asp136 fi His mutations increase the stability of So -RNase HI and 4· -RNase HI. We determined thecrystal structure of the sextuple mutant protein of So -RNase HI (6· -RNase HI) , in which ... (Tt -RNase HI) .Gly39 and Gly97 are conserved as Gly41 and Gly100 in Tt -RNase HI, respectively. Val76 is conserved as Val74 in Ec -RNase HI. Asn90 is conserved as Gln96 in RNase HI from a cyanobacterium....