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Biomedical subjects

F A Leone

Publications and source records attributed to F A Leone.

42 records · Page 3Linked to original sources
PubMed1976

Sheep prothrombin: purification and partial characterization.

A procedure for the preparation of highly purified sheep prothrombin is described. The purified zymogen, when subjected to disc gel electrophoresis in polyacrylamide, gave rise to one single band. Only alanine was found as N-terminal residue. Carboxypeptidases A and B failed to release any C-terminal residue. The isoelectric point, as determined by isoelectric focusing in polyacrylamide gel slab, was shown to be 4.9-5.0. Non-chromatographed, but not the purified zymogen, could be converted into active thrombin in half-saturated trisodium citrate seeded with thrombin. Pure sheep prothrombin showed 5.6% of neutral sugars and the following amino acid composition: Ala35, Arg44, Asx54-55, -Cys24, Glx72, Gly53-54, His8, Ile19, Leu45, Lys31, Met7, Phe23, Pro36, Ser34, Thr29-29, Trp16, Tyr19 and Val33, which accounts for a molecular weight of about 66 000 (amino acids only). The molecular weight as determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis after reduction by 2-mercaptoethanol, was shown to be 77 000 +/- 3000 (carbohydrates included).

Amino Acids↗
PubMed1976

Isolation and characterization of an active three-chain molecular species of bovine thrombin.

Partially purified bovine prothrombin was activated in half-saturated trisodium citrate seeded with thrombin, and the resulting thrombin was chromatographed on Amerblite IRC-50, followed by rechromatography on DEAE-Sephadex A-50. Five fractions, possessing both esterase and clotting activities, were partially isolated, but fraction VI was shown to be a pure three-chain active species with threonine, isoleucine and lysine, in 1:1:1 molar proportions as N-termini. The amino acid composition and C-termini of fraction VI were determinied. The molecular weights of the isolated chains, as determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, were 7300, 12000 and 19500 respectively. These data, when taken together with the amino acid sequence of the two-chain thrombin reported by Magnusson et al. (1975) [in Prothrombin and related Coagulation Factors, (Hember, H. C. & Veltkamp, J. J., eds.), pp. 25-46, Leiden University Press, Leiden], indicated that proteolysis occurred at the Arg(78)-Lys(79) peptide bond of the B chain of a precursor molecular species, thus converting this two-chain species into the three-chain active form described here.

Amino Acids↗
PubMed1976

Pig prothrombin: purification and properties.

A procedure for the preparation of highly purified pig prothrombin is described. Compared to the initial clotting activity of the starting plasma, this protein was purified 776 times with a final yield of 8 per cent. The purified zymogen showed a specific activity of 1,460 NH units/mg of protein , a molecular weight of 65,000 as determined by SDS-polyacrylamide disc gel electroesis, E 1.0 mg/ml 1.0 cm, 280 nm = 1.45 at pH 7.0 and the following amino acid composition: Asx 51, Thr 38, Glx 62, Pro 23, Gly44, Ala 25, Half-Cys 30, Val 35, Met 3, Ile 30, Leu 32, Tyr 19, Phe 22, Lys 36, His 8, Arg 28, and Trp 13, which accounts for a minimum molecular weight of 59,370 (carbohydrates not computed). Alanine was found as the only N-terminal residue. Carboxypeptidases A and B failed to release any C-terminal residue. By hydrazinolysis however 0.4 mole of serine was released per mole of prothrombin. The activation of crude and chromatographed pig prothrombin was investigated.

Amino Acids↗