| 1. |
- Morishita, Y., et al.
(författare)
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Direct observation of the initial-state distribution of the first electron transferred to slow highly charged ions interacting with a metal surface
- 2004
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 70:1
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Tidskriftsartikel (refereegranskat)abstract
- The electron transfer process in the interaction of a slow highlycharged ion with a metal surface has been studied employing amicrocapillary foil as a target. The combination of the target and avisible light spectroscopy allows us to directly evaluate the initial(n,ℓ) distributions of the first transferred electrons. It wasfound that observed lines were primarily attributed to Δn=1transitions with relatively high angular momenta ( ℓi≳4 ) . A cascade analysis revealed that the electron is selectivelytransferred to n≈ qin +1 states with a narrowdistribution width of δn≈2 (full width at half maximum). Theaverage initial principal quantum number is consistent with theprediction of the classical over-barrier model.
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| 2. |
- Sørensen, Kristoffer, et al.
(författare)
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Functional properties of recombinant factor V mutated in a potential calcium-binding site.
- 2004
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 43:19, s. 5803-5810
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Tidskriftsartikel (refereegranskat)abstract
- Activated coagulation factor V (FVa) is a cofactor of activated factor X (FXa) in prothrombin activation. FVa is composed of a light chain (LC) and a heavy chain (HC) that are noncovalently associated in a calcium-dependent manner. We constructed a recombinant FV Asp111Asn/Asp112Asn mutant (rFV-NN) to abolish calcium binding to a potential calcium-binding site in FVa in order to study the specific role of these residues in the expression of FVa activity. Whereas thrombin-activated recombinant FV wild type (rFV-wt) presented with stable FVa activity, incubation of rFV-NN with thrombin resulted in a temporary increase in FVa activity, which was rapidly lost upon prolonged incubation. Loss of FVa activity was most likely due to dissociation of HC and LC since, upon chromatography of rFVa-NN on a SP-Sepharose column, the HC did not bind significantly to the resin whereas the LC bound and could be eluted at high ionic strength. In contrast, rFVa-wt adhered to the column, and both the HC and LC coeluted at high ionic strength. In the presence of phospholipid vesicles, the loss of rFVa-NN activity was partially prevented by FXa, active site inhibited FXa, and prothombin in a dose-dependent manner. We conclude that the introduced amino acid substitutions result in a loss of the high-affinity (calcium-dependent) interaction of the HC and LC of FVa. We propose that the introduced substitutions disrupt the calcium-binding site in FV, thereby yielding a FV molecule that rapidly loses activity following thrombin-catalyzed activation most likely via dissociation of the HC and LC.
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| 3. |
- Yamazaki, Tomio, et al.
(författare)
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Molecular basis of quantitative factor V deficiency associated with factor V R2 haplotype.
- 2002
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Ingår i: Blood. - 1528-0020. ; 100:7, s. 2515-2521
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the molecular mechanisms of the quantitative factor V (FV) deficiency associated with the FV R2 haplotype, 4 missense mutations, Met385Thr, His1299Arg, Met1736Val, and Asp2194Gly, identified in the R2 haplotype allele, were analyzed by in vitro expression studies. The FV variant carrying all 4 mutations showed a markedly lower steady-state expression level than wild-type FV because of low synthesis rate and impaired secretion of the mutant protein. The Asp2194Gly mutation was found to play a key role in the impaired secretion of the mutant FV by interfering with its transport from the endoplasmic reticulum to the Golgi complex. The deleterious effect of the Asp2194Gly mutation was shown to be dominant among the 4 mutations. The Met385Thr mutation and His1299Arg mutation had no effect on steady-state expression levels, but the secretion rates of the mutant proteins were moderately decreased by these mutations. The His1299Arg mutation partially impaired glycosylation in the C-terminal part of the B-domain of the mutant FV, which was supposed to affect the secretion rate, but not the steady-state expression level. It was also suggested that the Met385Thr mutation partially impairs posttranslational modification of the mutant FV without affecting the steady-state expression level. No deleterious effect of the Met1736Val mutation was observed in terms of expression and intracellular processing. Our in vitro data strongly suggest that the naturally existing R2 haplotype mutant FV, which carries all 4 mutations, has the potential to result in quantitative FV deficiency in vivo owing to impaired expression of the mutant protein when the Asp2194Gly mutation is present.
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