Comparative effects of limited tryptic hydrolysis on physicochemical and structural features of seed 11S globulins.

The effect of the limited proteolysis by trypsin on selected seed storage 11S globulins (broad bean and pea legumins, glycinin and helianthinin) was studied by high-sensitive differential scanning calorimetry, fluorescence spectroscopy and analysis of proteolysis kinetics. Different behaviour of glycinin and helianthinin, on one hand, and broad bean and pea legumins, on the other, were observed: in the first group changes in the physicochemical characteristics of the proteins due to their limited proteolysis are more pronounced in comparison with the second one, in relation with the extent of primary structure modifications. The differences observed have been evaluated in relation with the amino acid sequence features of the four 11S globulin studied and agree with the literature data concerning the protein structural changes in the course of the limited proteolysis.

A comparative study of the role of the major proteinases of germinated common bean (Phaseolus vulgaris L.) and soybean (Glycine max (L.) Merrill) seeds in the degradation of their storage proteins.

Two types of cysteine proteases, low-specificity enzymes from the papain family and Asn-specific from the legumain family are generally considered to be the major endopeptidases responsible for the degradation of seed storage proteins during early seedling growth. The action of the corresponding enzymes (CPPh1 and LLP, respectively) from common bean (Phaseolus vulgaris L.) on phaseolin (the common bean storage protein), and on the homologous soybean (Glycine max (L.

Applying the increase in rate constants of cooperative proteolysis to the determination of transition curves of protein denaturation.

The transition curves of soybean glycinin egg lysozyme, bovine serum albumin (BSA) denaturation under the action of increasing urea concentration were monitored by determination of the increase in rate constants of cooperative enzymatic proteolysis. The results were compared with those obtained using intrinsic fluorescence and the number of accessible tyrosine. It was shown that the determination of the changes of proteolysis rate permits to disclose conformation changes not detected by other methods.

Does an asparaginyl-specific cysteine endopeptidase trigger phaseolin degradation in cotyledons of kidney bean seedlings?

An asparaginyl-specific cysteine endopeptidase which was named 'legumain-like proteinase' (LLP) and has an apparent molecular mass of 38.1 kDa was isolated from cotyledons of kidney bean (Phaseolus vulgaris L.) seedlings and partially characterized.

Detection of the isoenzymes of wheat grain proteinase A.

A new method for the purification of wheat cysteine proteinase A which plays a key role in the mobilization of seed storage proteins during germination has been developed. It consists of (NH4)2SO4 fractionation, gel filtration, and both ion-exchange and hydrophobic chromatography. Constancy of the specific activity of chromatographic fractions and their SDS-electrophoretic pattern indicates the homogeneity of the final enzyme preparation.

[Kinetics of a single proteolysis stem. Proteolysis of ovalbumin].

The course of one-by-one proteolysis of ovalbumin was followed by determining the residual protein. The reactions were found to be of pseudo-first order. The parallel occurring zipper proteolysis had no effect on this result, since it brought about only the splitting of ovalbumin into large fragments without any split-off of TCA-soluble peptides.

[Mechanism of ovalbumin proteolysis].

Papain, thermitase and pepsin at pH 4.0 hydrolyze ovalbumin to low molecular weight peptides. Simultaneously a stepwise formation of several short fragments resulting in the appearance of a group of high molecular weight fragments and a subsequent splitting of the latter into two fragments of intermediate molecular mass takes place.

Protein deamidase from germinating wheat grains.

A new enzyme catalyzing the deamidation of seed storage proteins was found in germinating wheat grains and was partially purified. It also acts on egg lysozyme, horse hemoglobin and reduced RNAse, glutamine and Gly-L-Gln-L-Tyr. No activity was observed when using ovalbumin, serum albumin, RNAse, insulin, asparagine and an asparagine-containing peptide.

Action of trypsin on glycinin. Mixed-type proteolysis and its kinetics; molecular mass of glycinin-T.

The formation of a relatively stable high-molecular-mass product on trypsin hydrolysis of glycinin (glycinin-T) is interpreted to be a result of 'zipper' proteolysis. Evidence of parallel one-by-one degradation of glycinin occurring after the formation of glycinin-T is presented. At a relatively low concentration of the substrate, the one-by-one proteolysis proceeds as a first-order reaction.

Colorimetric determination of phytate in unpurified extracts of seeds and the products of their processing.

The addition of orthophosphate (up to 20 micrograms/ml of phosphorus) and chlorogenic acid (up to 50 micrograms/ml) does not impair the colorimetric assay of phytate based on the decoloration of Fe3+-sulfosalicylate complex (M. Latta, and M. Eskin (1980) J.

Soybean seed 2-S globulins are not trypsin inhibitors.

Trypsin inhibitory activity found in 2-S soybean seed globulins is due to the coprecipitation of inhibitors during the isolation of globulins.

[Purification and partial characterization of protease B from germinating vetch seeds].

The sulfhydryl protease B was isolated from the cotyledons of 8-day old vetch seedlings and purified 1580-fold with a 38% recovery. The preparation obtained proved to be homogeneous by DEAE-cellulose chromatography and polyacrylamide gel electrophoresis. The molecular weight of the enzyme as shown by Na-DS gel electrophoresis is 38 000.

[Modification of vetch seed reserve proteins during germination and limited proteolysis].

The split-off 1-2 short peptides is the first stop in the endogenous protease A effect on the vetch legumin, which results in a step-wise rise of its hydrolyzability by two other endogenous proteases (B and C). Short neutral and basic peptides are consecutively split off from the acid subunits in the course of subsequent hydrolysis by protease A, while the breakdown of these subunits into larger fragments, which are retained in the legumin molecule by non-covalent bonds, occurs later. Similar results were obtained in experiments on trypsin action of legumin.

The action of pepsin on the reserve proteins of some leguminous seeds.

The action of pepsin on the 11-S and 7-S proteins of vetch, 11-S protein of soybean and 7-S protein of Phaseolus vulgaris was investigated. The first three proteins are hydrolyzed almost completely, the rate of hydrolysis being close to that of hemoglobin, while the hydrolysis of Ph. vulgaris 7-S protein stops after the cleavage of only 2,4% of peptide bonds.

The action of trypsin and chymotrypsin on the reserve proteins of some leguminous seeds.

The action of trypsin on the reserve proteins of the leguminous seeds belonging to Vicieae and Phaseoleae tribes was investicated. The hydrolysis of11S and 7S proteins of Vicieae proceeds relatively fast and some of the proteins are hydrolyzed practically completely. The hydrolysis of most of the investigated reserve proteins of the Phaseoleae tribe proceeds much slower, while that of 7S proteins of four Phaseolus species of American origin stops after the cleavage of only 10-20% of peptide bonds capable of reacting.

[Isolation and characteristics of benzoyl-DL-arginl-p-nitroanilide-hydrolysing enzyme (BAPAase) from vetch seedlings].

The enzyme hydrolysing N-benzoyl-D,L-arginine-p-nitroanilide (BAPA). is isolated from vetch seedlings and 1600-fold purified by means of chromatography on DEAE-cellulose, hdroxyapatite and gel filtration through Sephadex G-100. The preparation is chromatographically homogenous, but disc electrophoresis in polyacrylamide gel revealed an insignificant contamination by inactive proteins.

[Some arylamidases from vetch seeds].

Hydrolysis of L-phenylalanyl-p-nitroanilide (PPA) and glycyl-p-nitroanilide by extracts from resting vetch seeds was shown to be the effect of two different arylamidases. One of them, PPAase, was 2000-fold purified on hydroxylapatide, DEAE-cellulose and by gel filtration through Sephadex G-100. The preparation obtained was nearly homogenous chromatographycally.