[Trypsin inhibitor from Gleditsia triacanthos L. seeds]. / Ingibitor tripsina iz semian gledichii (Gleditsia triacanthos L.).

The trypsin inhibitor from Gleditsia triacanthos (L.) seeds was purified by affinity chromatography on a column with trypsin-Sepharose 4B. The isolated inhibitor is a single-chain protein with molecular weight of about 20 000. The inhibitor suppresses bovine trypsin at a molar rate of 1 : 1, but weakly inhibits chymotrypsin in a non-stoichiometric manner. Some properties of the isolated inhibitor closely resembled those of soybean trypsin inhibitor (Kunitz).

[Conformational changes during proteinase inhibitor proteins interaction with chymotrypsin]. / Konformatsionnye izmeneniia pri vzaimodeistsvii belkov - ingibitorov proteinaz s khimotripsinom.

Using CD-spectroscopy and fluorescent probe technique, the formation of complexes of chymotrypsin with two highly efficient protein inhibitors of plant origin, e. g. inhibitors from pea seeds and potato tubers, was studied. The CD spectra recorded during the formation of the enzyme--potato tuber inhibitor complexes suggest that the inhibitor molecule. This is correlated with the data on fluorescence of ANS coupled to the inhibitor and to the inhibitor--chymotrypsin complex. In case of the pea seed inhibitor the changes in the CD spectra during the complex formation can result from the changes in the environment of the disulfide bonds in the protein--inhibitor molecule.

[Modification of tyrosine residues in the protein inhibitor of potato proteinases]. / Modifikatsiia ostatkov tirozina v belke-ingibitore proteinaz iz kartofelia.

Treatment of a native protein inhibitor of proteinases by tetranitromethane results inmodification of 3 (out of 8) tyrosine residues in each of the two subunits within the inhibitor molecule. Nitration of surface tyrosines does not change the corformation of the protein and has no effect on its ability to inhibit chymotrypsin. At the same time the tetranitromethane-treated inhibitor possesses a decreased activity with respect to trypsin. In the presence of 0,5 M DS-Na practically all tyrosine residues of the protein are nitrated.

[Circular dichroism spectra of protein proteinase inhibitors]. / Spektry krugovogo dikhroizma belkov-ingibitorov Proteinaz.

The circular dichroism spectra of two protein proteinase inhibitors were studied. The CD spectrum of the kidney bean inhibitor is similar to those of other low molecular weight inhibitors from legume seeds. The potato inhibitor in its native state is characterized by a low content of alpha-helices, which is increased in the presence of sodium dodecyl sulfate.

[Interaction of protein inhibitor from potato (protein with pI 7.3) with proteinases]. / Vzaimodeistvie belka-ingibitora iz kartofelia (belok pI 7,3) s Proteinazami.

The interaction between protein inhibitor of serine proteinases from potato (protein with pI 7.3) and enzymes was investigated. The main complex present in mixtures of the inhibitor with trypsin, chymotrypsin or subtilisin contained one dimeric inhibitor molecule and one molecule of either enzyme. At high ratio enzyme/inhibitor the complexes were formed which contained more than one bound enzyme molecule. The interaction with enzymes does not include the proteolytic degradation of inhibitor with concomitant lowering of its molecular weight. The inhibitor obtained after the dissociation of inhibitor--chymotrypsin complex, preserve its capacity to form stable complexes with the enzyme.

[Physico-chemical properties of a protein-inhibitor of serine proteinases from the potato]. / Izuchenie fiziko-khimicheskikh svoistv belka--inhibitora serinovykh proteinaz iz kartofelia

Serine proteases inhibitor with pl-7.3, isolated from potatoe tubers by isoelectric focusing procedure as described previously (V.V. Mosolov et al., Bioorganic Chem., 1, 1449, 1975), was homogeneous under ultracentrifugation, having sedimentation coefficient S20,w 2.8S. Its molecular weight, investigated by sedimentation equilibrium and gel filtration through Sephadex G-100, was found to be 32500 and 31500 respectively. The Stokes radius R and frictional ratio f/fo were found to be 24 A and 1.14. The molecular weight of the inhibitor as determined by sodium dodecylsulfate polyacrylamide electrophoresis was twice as low as determined in ultracentrifuge and by gel filtration procedure. It is suggested that the inhibitor is dimer and consists of two protomers of equal molecular weight.