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1

Squash inhibitor family of serine proteinases

100%

Otlewski J., Krowarsch D.

Acta Biochimica Polonica

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1996

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tom 43

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nr 3

Squash inhibitors of serine proteinases form an uniform family of small proteins. They are built of 27-33 amino-acid residues and cross-linked with three disulfide bridges. The reactive site peptide bond (Pl-Pl') is between residue 5 (Lys, Arg or Leu) and 6 (always lie). High resolution X-ray structures are available for two squash inhibitors complexed with trypsin. NMR solution structures have also been determined for free inhibitors. The major structural motif is a distorted, triple-strai:ded antiparallel p-sheet. A similar folding motif has been recently found in a number of proteins, including: conotoxins from fish-hunting snails, carbo- xypeptidase inhibitor from potato, kalata B1 polypeptide, and in some growth factors (e.g. nerve growth factor, transforming growth factor P2, platelet-derived growth factor). Squash inhibitors are highly stable and rigid proteins. They inhibit a number of serine proteinases: trypsin, plasmin, kallikrein, blood clotting factors: Xa and XII*, cathepsin G. The inhibition spectrum can be much broadened if specific amino-acid substitutions are introduced, especially at residues which contact proteinase. Squash inhibitors inhibit proteinases via the standard mechanism. According to the mechanism, inhibitors are substrates which exibit at neutral pH a high fccWKm index for hydrolysis and resynthesis of the reactive site, and a low value of the hydrolysis constant.

2

Serine proteinase inhibitor family in squash seeds: mutational variability mechanism and correlation

75%

Leluk J.

Cellular and Molecular Biology Letters

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2000

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tom 05

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nr 1

Proteinase inhibitors from squash seeds were analyzed for mutational variability. The non-homologous positions were subjected to an analysis of the interrelation between occurring residues and the mechanism of variability, using the algorithm of genetic semihomology [1]. The study also concerned mutational correlation at particular positions and their contact with each other. It was observed that: the number of residues occupying particular positions varies from 1 to 8 the mechanism of variability is based on single point mutation the variable positions are seldom in contact with each other the mutations in distant positions (not in contact with each other) are correlated with each other the correlated mutations refer to those positions which are far from the reactive site of the inhibitor the mutational variability in primary structure within this family is not consistent with the Markovian model of amino acid replacement.

3

3'Noncoding sequences of the CTA 1 gene enhance expression of the recombinant serine protease inhibitor, CPTI II, in Saccharomyces cerevisiae

63%

Stankiewicz M., Rempola B., Fikus M.

Acta Biochimica Polonica

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1996

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tom 43

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nr 3

Expression of the gene coding for the recombinant trypsin inhibitor, CPTI II, was enhanced tenfold when yeast transcription terminating sequences were added to the expression cassette of the pJK6 yeast vector. The yield was further increased about 20% in the BJ5464 yeast strain, defective in vacuolar proteases.

Ograniczanie wyników

2 Acta Biochimica Polonica

1 Cellular and Molecular Biology Letters

1 Fikus M.

1 Krowarsch D.

1 Leluk J.

1 Otlewski J.

1 Rempola B.

1 Stankiewicz M.

1 2000

2 1996

Squash inhibitor family of serine proteinases

Serine proteinase inhibitor family in squash seeds: mutational variability mechanism and correlation

3'Noncoding sequences of the CTA 1 gene enhance expression of the recombinant serine protease inhibitor, CPTI II, in Saccharomyces cerevisiae