Johannes Thomsen

Characterization of a Cobalamin-binding Plasma Protein from a Patient with Hepatoma

A cobalamin-binding protein has been purified by affinity chromatography from plasma of a patient with hepatoma and a 10,000-fold increase in the concentration of the plasma cobalamin-binding capacity. The protein behaved as normal transcobalamin I in gel filtration, agar gel electrophoresis, immunoelectrophoresis, precipitation by ammonium sulphate, and cobalamin-binding studies. The protein contained 38 per cent carbohydrate, and the relative molecular mass based on amino acid and carbohydrate analyses was 69,000. The molar absorption coefficient of cyanocobalamin bound to the protein was determined to be 36,000 at 362 nm. On amino acid sequencing, one amino terminal was found, and the first 13 residues were determined as Glu-Ile-Ser/Cys-Glu-Val-Ser/Cys-Glu-Glu-Asx-Tyr-Ile-Arg-Leu/Ile.

Primary structure of human intrinsic factor: progress report on cyanogen bromide fragmentation

Human intrinsic factor purified by labile ligand affinity chromatography was cleaved with cyanogen bromide and fractionated by gel filtration. Four of the fragments were purified and sequenced to a total of eighty-four amino acid residues. Including the N-terminal amino acids this amounts to one third of the total amino acid sequence of human intrinsic factor. One of the fragments contained a tyrosine labelled only on iodination of intrinsic factor devoid of cobalamin.

Amino Terminal Sequence of Human Intrinsic Factor

Olesen, H., Nexo, E., Lous, P., Thomsen, J. & Bucher, D. Amino Terminal Sequence of Human Intrinsic Factor. Scand. J. clin. Lab. Invest. 36, 527–529, 1976.The N-terminal sequence of human intrinsic factor is hereby reported as: 1 5 10 Ser-Thr-Gln-Thr-Gln-Ser-Ser-Cys-Ser-Val-Pro-Ser-Ala-Gln-15 20 25 Glu-Pro-Leu-Val-Asn-Gly-Ile-Gln- -Leu-Met-Gul-Thr-It is concluded that the cysteine at position 8 is involved in a disulfide bridge in the native protein.

Biosynthetic Human Growth Hormone Identical to Authentic Material

The major component of human growth hormone (hGH) is a protein with 191 amino acid residues, and a molecular weight of approximately 22,000 D (22K-hGH). A minor component which constitutes about 5% of the more abundant form has a molecular weight of approximately 20,000 D. The minor form is derived from the major by deletion of 15 amino acid residues (32–46 of the 22K-isomer). Both molecules are single stranded, and two disulfide bridges stabilizes the structure. The N-terminus as well as the C-terminus is phenylalanine (Chawla et al., 1983).