The nucleotide sequence of asparagine tRNA from brewer's yeast has been determined using postlabeling methods. The primary structure is as follows: pG-A-C-U-C-C-A-U-G-m2G-C-C-A-A-G-D-D-G-G-D-D-A-A-G-G-C-m2 2G- U-G-C-G-A-C-U-G-U-U -t6A-A-psi-C-G-C-A-A-G-A-D-m5C-G-U-G-A-G-T-psi-C-A-m1A-C-C-C-U-C-A-C-U-G -G-G-G- U -C-G-C-C-A. Its anticodon G-U-U can recognize the two codons for asparagine.

Aspartate-tRNA Ligase↗

PubMedDate not supplied

Stimulation of rat kidney, spleen and brain DNA-(cytosine-5-)-methyltransferases by divalent cobalt ions.

Rat kidney, spleen, brain, and liver DNA-methylases were partially purified by chromatography on DEAE-Trisacryl columns and their catalytic properties were studied. Crude extracts contain one or several inhibitors which are thermostable and resistant to acidic or alkaline treatments and which can be eliminated by dialysis, or by chromatography on DEAE-Trisacryl. These are most probably divalent ions, such as, Pb2+, Zn2+, Cu2+, Fe2+, Mg2+, Mn2+ or Ca2+, which inhibit the DNA-methylase activity. However, Co2+, at concentrations ranging from 0.05 mM to 1 mM, has an efficient stimulatory action on spleen, kidney or brain DNA-methylase activity. The spleen DNA-methylase activity on chicken erythrocyte DNA could be increased 10-fold, by a 0.2 mM concentration of Co2+, but no stimulation was found with liver DNA-methylase. The fact that significant differences exist between the DNA-methylases from the different organs in their behavior towards Co2+ could indicate that these enzymes are different.

Animals↗

PubMedDate not supplied

Primary structure of three tRNAs from brewer's yeast: tRNAPro2, tRNAHis1 and tRNAHis2.

The primary structures of three brewer's yeast tRNAs: tRNAPro2 and tRNAHis1 and 2 have been determined (Formula:see text) The U* in the anticodon U*-G-G of tRNAPro2 is probably a derivative of U; tRNAPro2 has 80 per cent homology with mammalian tRNAsPro. tRNAHis1 and tRNAHis2 differ by only 5 nucleotides; they have identical anticodons and may therefore recognize both codons for histidine; they have an additional nucleotide at the 5' end. As in all other sequenced tRNAsHis this nucleotide is not paired with the fourth nucleotide from acceptor adenosine. All three sequenced tRNAs have a low degree of homology with their counterparts from yeast mitochondria.

Anticodon↗