A procedure for the purification of elongation factor 1 (EF-1) from KrebsII mouse ascites cells is described. Ascites EF-1 occurs in multiple forms of different molecular weight like the corresponding enzymes from calf brain and rat liver. Biogel A-5m chromatography of our purest EF-1 resulted in a pattern indicating the presence of different molecular weight components. However, only a single polypeptide band was observed when this same material was analysed by electrophoresis on acrylamide gels containing sodium dodecylsulphate. With this method the molecular weight of the EF-1 polypeptide chain was determined to be 47 000. It is suggested that the occurrence of multiple forms of EF-1 is due to the association of 47000-mol. wt subunits to form aggregates of different sizes.The factor has essentially the same enzymatic properties which were described for EF-1 from ret,iculocytes, calf brain and rat liver. The attachment of aminoacyl-tRNA to ribosomes catalyzed by EF-1 follows a strict 1 : 1 stoichiometry. EF-2 when introduced into the ribosomal binding assay allows the recycling of EF-1 and subsequent synthesis of polypeptide chains. The possible implications of this finding with respect to the conditions which allow stoichiometric or catalytic function of EF-1 are discussed.Elongation factor 1 functions in polypeptide synthesis by catalyzing the attachment of aminoacyl-tRNA to the ribosomal acceptor site [l, 21. This reaction has been shown to require GTP and some evidence has recently been produced suggesting the formation of a ternary complex between aminoacyl-tRNA, GTP and EF-1 as a necessary intermediate in the binding of aminoacyl-tRNA to the ribosomal A-site [3,4]. It has also been shown that the interaction of the aminoacyl-tRNA anticodon with the complementary codon is a prerequisite for the cleavage of those GTP molecules which became attached to the ribosomal A-site as part of this ternary complex [3]. Apart from this specific GTP hydrolysis into GDP and phosphate, an uncoupled GTPase activity is displayed by EF-1 in the presence of ribosomes and arninoacyl-tRNA [5,6], the functional significance of which is not known.I n spite of the advances which have recently been made in understanding the function of EF-1, many questions pertaining to the structure as well as the function of this protein remain to be resolved.

Phosphonate analogue 5 of the lipid A precursor 4 has been prepared from phosphonate 2 and nucleotide 3 with the help of lipid A synthase, isolated from the overproducing Escherichia coli mutant MC 1061 (delta 2512) or JB1104 (delta 2514). The biological properties of phosphonate 5 and phosphate 4 are quite similar to each other as compared in the limulus amoebocyte lysate assay, by the activation of the RAW264 murine macrophagelike cell line (determined by stimulation of ornithine decarboxylase), and by the pyrogenicity in rabbits. Hydrolytic removal of the 1-phosphate group of 4 is thus not a prerequisite for its biological activity.

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