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Amino acid substitu...
Amino acid substitutions in the N-terminal segment of cystatin C create selective inhibitors of lysosomal cysteine proteinases
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Mason, R W (författare)
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Sol-Church, K (författare)
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- Abrahamson, Magnus (författare)
- Lund University,Lunds universitet,Avdelningen för klinisk kemi och farmakologi,Institutionen för laboratoriemedicin,Medicinska fakulteten,Division of Clinical Chemistry and Pharmacology,Department of Laboratory Medicine,Faculty of Medicine
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(creator_code:org_t)
- 1998
- 1998
- Engelska.
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Ingår i: Biochemical Journal. - 0264-6021. ; 330:2, s. 833-838
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Abstract
Ämnesord
Stäng
- We used site-directed mutagenesis to alter the specificity of human cystatin C, an inhibitor with a broad reactivity against cysteine proteinases. Nine cystatin C variants containing amino acid substitutions in the N-terminal (L9W, V10W, V10F and V10R) and/or the C-terminal (W106G) enzyme-binding regions were designed and produced in Escherichia coli. It was discovered that the inhibition profile of the cystatin could be altered by changing residues 9 and 10, which are proposed to bind in the S3 and S2 substrate-binding pockets respectively of the enzymes. All of the variants with substitutions in the N-terminal segment displayed decreased binding to cathepsins B and H, indicating that the S3 and S2 pockets of these enzymes cannot easily accommodate large aromatic residues. The introduction of a charged residue into S2 (variant V10R) created a more specific inhibitor to distinguish cathepsin B from cathepsin H. Cathepsin L showed a preference for larger aromatic residues in S2. In contrast, cathepsin S preferred phenylalanine to valine in S2, but bound less tightly to the V10W cystatin variant. The latter variant proved to be valuable for discriminating between cathepsin L and cathepsin S (Ki 2.4 and 190 pM respectively). The equilibrium dissociation constant of the complex between cathepsin L and variant L9W/W106G showed little difference in affinity from that of the cathepsin L complex with the singly substituted W106G variant. In contrast, the L9W/W106G variant displayed increased specificity for cathepsin S with a Ki of 10 pM. Our results clearly indicate differences in the specificity of interaction between the N-terminal region of cystatin C and cathepsins B, H, L and S, and that, although cystatin C has evolved to be a good inhibitor of all of the mammalian cysteine proteinases, more specific inhibitors of the individual enzymes can be engineered.
Ämnesord
- MEDICIN OCH HÄLSOVETENSKAP -- Medicinska och farmaceutiska grundvetenskaper -- Läkemedelskemi (hsv//swe)
- MEDICAL AND HEALTH SCIENCES -- Basic Medicine -- Medicinal Chemistry (hsv//eng)
- MEDICIN OCH HÄLSOVETENSKAP -- Medicinska och farmaceutiska grundvetenskaper -- Farmakologi och toxikologi (hsv//swe)
- MEDICAL AND HEALTH SCIENCES -- Basic Medicine -- Pharmacology and Toxicology (hsv//eng)
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