Location of. gamma. -carboxyglutamyl residues in partially carboxylated prothrombin preparations
Prothrombin contains 10-..gamma..-carboxylglutamyl (Gla) residues in the N-terminal (fragment 1) domain of the protein. Following anticoagulant administration, a spectrum of undercarboxylated, physiologically less active forms of prothrombin is secreted into bovine or human plasma. The sites of undercarboxylation in these prothrombin species have now been investigated. Plasma containing a mixture of partially carboxylated forms of prothombin was obtained from a dicoumarol-treated bovine, and three pools of partially carboxylated (four, six, or eight Gla) species were purified by adsorption onto barium citrate and barium oxalate, ammonium sulfate fractionation, and chromatography. Fragment 1 obtained from these variants was equilibrated with /sup 3/H/sub 2/O and heated in a dry state to decarboxylate Gla and incorporate /sup 3/H into the resulting Glu residues. This peptide was then sequenced by Edman degradation, and the specific radioactivity of PTH-Glu was determined for each potential Gla-containing site. Data obtained from normal prothrombin fragment 1 fit a linear model when the log of specific activity of PTH-Glu was plotted against the cycle number. Analysis of the 80% variant showed a decrease in carboxylation only in the last two Gla residues, while data obtained from the 60% variant indicated a general decrease in carboxylation from the most amino-terminal of the Gla residues. In the 40% Gla variant, all but the most amino-terminal of the Gla residues appeared to be undercarboxylated. These data indicate that the ..gamma..-carboxylation of glutamyl residues in prothrombin does not occur randomly but instead with preferential carboxylation of the most amino-terminal Gla residues. When carboxylation is limited, the impairment of carboxylation is more severe at the more carboxyl-terminal residues.
- Research Organization:
- Univ. of Wisconsin, Madison (USA)
- OSTI ID:
- 5983650
- Journal Information:
- Biochemistry; (United States), Vol. 27:23
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GLUTAMINE
BIOCHEMISTRY
PROTHROMBIN
MOLECULAR STRUCTURE
CARBOXYLATION
LIQUID COLUMN CHROMATOGRAPHY
TRITIUM COMPOUNDS
TRITIUM OXIDES
AMIDES
AMINO ACIDS
BLOOD COAGULATION FACTORS
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
CHROMATOGRAPHY
COAGULANTS
DRUGS
HEMATOLOGIC AGENTS
LABELLED COMPOUNDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
SEPARATION PROCESSES
550201* - Biochemistry- Tracer Techniques