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Calcium Ion Binding...
Calcium Ion Binding to Pancreatic Phospholipase A2 and Its Zymogen : A 43Ca NMR Study
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- Drakenberg, Torbjörn (författare)
- Lund University,Lunds universitet,Biofysikalisk kemi,Centrum för Molekylär Proteinvetenskap,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Biophysical Chemistry,Center for Molecular Protein Science,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH
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- Andersson, Thomas (författare)
- Lund University
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- Forsén, Sture (författare)
- Lund University
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- Wieloch, Tadeusz (författare)
- Lund University,Lunds universitet,Laboratory for Experimental Brain Research,Forskargrupper vid Lunds universitet,Lund University Research Groups
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(creator_code:org_t)
- 2002-05-01
- 1984
- Engelska 6 s.
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 23:11, s. 2387-2392
- Relaterad länk:
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http://dx.doi.org/10...
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https://lup.lub.lu.s...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- Calcium ion binding to phospholipase A2 and its zymogen has been studied by 43Ca NMR. The temperature dependence of the band shape of the calcium-43 NMR signal has been used to calculate the calcium ion exchange rate. The on-rate was calculated to be 5 × 106 M-1 s-1, which is 2 orders of magnitude less than the diffusion limit of the hydrated Ca2+ ion in water. The 43Ca quadrupole coupling constant for calcium ions bound to phospholipase, χ = 1.4 MHz, is significantly larger than those found for EF-hand proteins, indicating a less symmetric site. For prophospholipase A2, we found χ = 0.8 MHz, indicating a calcium binding site, which is somewhat more symmetric than the EF-hand sites. The dependence of the Ca NMR band shape on the calcium ion concentration showed that there are two cation binding sites on the phospholipase A2 molecule: K1 = 4 × 103 M-1 and K2 = 20 M. The strong site was found to be affected by a pKa = 6.5 and the weak site by pKa = 4.5.
Ämnesord
- NATURVETENSKAP -- Kemi -- Teoretisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Theoretical Chemistry (hsv//eng)
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