Several transfer RNA precursors which accumulate in a strain of Escherichia coli temperature-sensitive for RNase P have been described. These precursors range from 135 to 690 nucleotides in length. Their tRNA content has been determined by digestion of the precursors to 4 S RNA, followed by Sanger fingerprint analysis of the purified 4 S material. Identification of some of these tRNAs, as well ...

B Activators capable of bringing about conversiou of a proenzyme of blood, profibrinolysin (plasminogen), to the active proteolytic enzyme, fibnnolysin (plasmin), have been reported to be present in the tissues of veins. Astrup and coworkers' isolated a tissue activator from veins which promoted an in vitro activation of profibrinolysin. Studies in vivo by Kwaan et al." have indicated the prese...