Establishment of two distinct protein domains in blue crab Callinectes sapidus metallothionein-I through heteronuclear (1H113Cd) and homonuclear 1H1H) correlation NMR experiments
✍ Scribed by Surinder S. Narula; Ian M. Armitage; Marius Brouwer; Jan J. Enghild
- Book ID
- 102951526
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 698 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Abstract
Metallothionein is a cysteine‐rich metal‐binding protein whose biosynthesis is closely regulated by the level of exposure of an organism to zinc, copper, cadmium, etc., metal salts. The metallothionein from the crab Callinectes sapidus is known to bind six divalent metal ions. The ^113^Cd NMR spectrum of the ^113^Cdsubstituted protein shows six distinct ^113^Cd resonances spanning a chemical shift range of 620–665 ppm, indicating the presence of six distinct tetrahedrally coordinated divalent metal ion binding sites. Heteronuclear ^1^H^113^Cd correlation experiments revealed all the metal‐to‐cysteine connectivities present in this protein and the 2X(2^113^Cd)‐;filtered COSY experiment revealed that six cysteines are involved in the ligation of two Cd^2+^ ions. Additionally, following the complete sequential resonance assignment of the ^1^H NMR data, the two separate Cd~3~Cys~9~ metal binding clusters can be shown to reside in two distinct protein domains.