Tatyana A. Valueva, Tatyana A. Revina, Vladimir V. Mosolov, Reinhard Mentele
Primary Structure of Potato Kunitz-Type Serine Proteinase Inhibitor
The serine proteinase inhibitor (PSPI-21) isolated from
potato tubers (Solanum tuberosum L.) comprises two
protein species with pI 5.2 and 6.3, denoted as PSPI-21-5.2 and PSPI-21-6.3, respectively. They were separated
by anion exchange chromatography on a Mono
Q FPLC column. Both species tightly inhibit human
leukocyte elastase, whereas their interaction with
trypsin and chymotrypsin is substantially weaker. The
sequences of both PSPI-21-5.2 and PSPI-21-6.3 were
determined by analysis of overlapping peptides obtained
from the oxidized or reduced and S-pyridylethylated
proteins after digestion with trypsin or pepsin.
Both species of PSPI-21 are composed of two chains,
named chains A and B, which are linked by a disulfide
bridge between Cys(146) and Cys(157). The other disulfide
bridge is located within the A chains between
Cys(48) and Cys(97). The amino acid sequences of the
large A chains of the two forms, consisting of 150
amino acids residues each, differ in a single residue at
position 52. The small chains B, containing 37 and 36
residues in PSPI-21-6.3 and PSPI-21-5.2, respectively,
have nine different residues. The entire amino acid
sequences of the two inhibitors show a high degree
of homology to the other Kunitz-type proteinase inhibitors
from plants.
Biological Chemistry, Walter de Gruyter
Print ISSN: 1431-6730
Volume: 381, 12/2000
Pages: 1215 - 1221
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