No abstract

The mRNA sequence of the human intrinsic clotting factor IX (Christmas factor) has been completed and is 2802 residues long, including a 29 residue long 5′ non‐coding and a 1390 residue long 3′ non‐coding region, but excluding the poly(A) tail. The factor IX gene is approximately 34 kb long and we define, by the sequencing of 5280 residues, the presumed promoter region, all eight exons, and some intron and flanking sequence. Introns account for 92% of the gene length and the longest is estimated to be 10 100 residues. Exons conform roughly to previously designated protein regions, but the catalytic region of the protein is coded by two separate exons. This differs from the arrangement in the other characterized serine protease genes which are further subdivided in this region.

Th ¶e nucleotide sequence of the nucleoprotein gene of influenza A/trT/60/68 was established after using improved cloning methods to obtain full length cDNA clones in pBr322. The gene is 1565 residues long and codes for a basic protein of 498 amino acids. There are only 30 amino acid differences between it and the hamologous sequence in A/PR/8/34, all occurring as point mutations. Assuming a camcmn lineage, the evolutionary rate of divergence of the two strains is 0.18% amino acid per year. This confirms there is a slow but significant rate of evolution.

1. The stereoisomers of delta-(alpha-aminoadipyl)-L-cysteinylvaline (LLD, LLL and DLD) were synthesized from valine labelled with 3H in its methyl groups or in the alpha position. L-Cysteinyl-D-[4,4'-3H]valine was also synthesized. 2. 3H was incorporated into a compound that behaved like penicillin N when the LLD tripeptide containing either a methyl- or an alpha-labelled valine residue was incubated with a cell-free system prepared by lysis of protoplasts of Cephalosporium acremonium. 3. Incorporation was not observed under these conditions from the labelled all-L- or DLD-tripeptide, from L-cysteinyl-D-[4,4'-3H]valine, or of Penicillium chrysogenum appeared to be the LLD isomer, like that from C. acremonium. 5. These findings are discussed in relation to penicillin biosynthesis.

In a cell-free system prepared by osmotic lysis of protoplasts of Cephalosporium acremonium, isopenicillin N is converted into penicillin N. The epimerase activity of the system is labile.