Glycosyl part identified within Balanites aegyptiaca fruit protease.

The many milk-clotting proteases from plant are glycosylated; attachment of monosaccharides to enzyme is an advantage for its activity and stability. In this study, gas chromatography coupled to mass spectrometry-electrospray ionization was used to identify glycans bond to proteases purified from Balanites aegyptiaca fruits pulp through cation exchange chromatography. Carbohydrates were identified according to the retention time and the ion at m/z after derivation by heptafluorobutyric acid. The chromatograms obtained from monosaccharides analysis revealed the presence of galactose, mannose, arabinose, xylose, rhamnose and glucuronic acid. The mass spectrometry-electrospray ionization spectra corroborated these findings.

A simple method for the two-step preparation of two pure haemorphins from a total haemoglobin peptic hydrolysate by conventional low-pressure chromatographies.

The development of a simple purification method for two haemorphins, VV-haemorphin-7 (Val-Val-Tyr-Pro-Trp-Thr-Gln-Arg-Phe) and VV-haemorphin-4 (Val-Val-Tyr-Pro-Trp-Thr), from a total peptic haemoglobin hydrolysate is described. Cation-exchange chromatography on CM-Sephadex was used as a pre-fractionation step for the hydrolysate. VV-haemorphin-7 and VV-haemorphin-4 were eluted in two different fractions. The second and final purification step was hydrophobic-interaction chromatography on phenyl-Sepharose, which allowed the isolation of the two pure haemorphins. Haemoglobin and globin hydrolysates were compared as starting materials. For easy recovery of haemorphins and easy adjustment of conditions for final purification, a volatile buffer, ammonium acetate buffer, pH 6.5, was employed. This process, which allowed the preparation of pure haemorphins from a total protein hydrolysate, could be scaled up and used in the food industry.

Antibacterial activity of a pepsin-derived bovine hemoglobin fragment.

Peptic digestion of bovine hemoglobin yields a fragment with antibacterial activity. This peptide was purified to homogeneity by a two-step procedure including anion exchange chromatography and preparative reversed-phase HPLC. Mass determination and fragmentation indicated that this peptide corresponded to the 1-23 fragment of the alpha chain of hemoglobin. The minimum inhibitory concentration and mode of action of this peptide towards Micrococcus luteus strain A270 were determined. Hemolytic assay, interaction with liposomes, and study of its structure in solution were also performed.

Improvement of Staphylococcus aureus-V8-protease hydrolysis of bovine haemoglobin by its adsorption on to a solid phase in the presence of SDS: peptide mapping and obtention of two haemopoietic peptides.

Hydrolysis of bovine haemoglobin by the V8 protease from Staphylococcus aureus (EC 3.4.21.19) was studied in the presence of SDS in a homogeneous-phase and in a solid-phase system. In both cases, hydrolyses were performed at 37 degrees C, in 50 mM phosphate buffer, pH 6.0, containing 0.1% SDS. Solid-phase hydrolyses were carried out with haemoglobin adsorbed on a negatively charged hydrophobic support, namely Amberlyst 15Wet (Rohm and Haas). The peptides were isolated from the hydrolysates by reverse-phase HPLC and analysed for their amino acid composition on a Waters Pico-Tag column, confirmed by second-order derivative spectrometry or by MS. A peptide map of the hydrolysates was drawn up, and numerous new cleavages in haemoglobin chains were observed, especially after Asp. This study showed that SDS permitted a dramatic improvement in the hydrolysis of whole haemoglobin by V8 protease in both homogeneous-phase and solid phase systems after adsorption of haemoglobin on to an anionic support. Moreover, in the heterogeneous phase, all the theoretical cleavage sites of V8 protease, Asp as well as Glu bonds, were hydrolysed, except for four sites which were resistant owing to strong interactions with the support. These results led to us obtain two haemopoietic peptides, namely peptide alpha (Leu(76)-Pro-Gly-Ala-Leu-Ser-Glu(82)) and peptide beta (Lys(94)-Leu-His-Val-Asp-Pro-Glu(100)). These active peptides have never before been prepared from bovine haemoglobin, and they may have great potentialities in biotechnology.

Selectivity modification of chymotryptic hydrolysis of haemoglobin by its adsorption on a solid phase.

A change of selectivity of the chymotryptic hydrolysis of haemoglobin was evidenced when the protein was adsorbed on to a negatively charged hydrophobic support. The hydrolysis in heterogeneous phase improved the obtaining of positively charged and hydrophobic peptides as carriers of water-insoluble molecules. Haemoglobin adsorption on Amberlyst 15Wet was carried out in 0.1 M Tris/HCl buffer at pH 6.0. Chymotryptic hydrolysis was performed for 72 h at 37 degrees C in the same buffer. In solution, the presence of SDS was necessary to achieve the complete hydrolysis of haemoglobin chains, whereas it was not needed when haemoglobin was previously adsorbed on to the resin. The hydrolysis proceeded more slowly in heterogeneous phase than in homogeneous solution because of the diffusional restrictions but, at the end of the hydrolysis, the peptide populations were very different, as shown by reversed-phase HPLC. Moreover their functional properties were different too, since the haemoglobin hydrolysate obtained by heterogeneous catalysis had a better solubilizing ability towards the water-insoluble molecule, protoporphyrin IX, a photosensitizer for photodynamic therapy. A time-course study of the hydrolysis was performed to follow the evolution of a marker peptide (1-14alpha), which allowed us to explain the change in the selectivity of the chymotryptic reaction. This change could be due to a slowing down of the cut-off of some sites interacting with the support.

Comparison of the IgE titers to bovine colostral G immunoglobulins and their F(ab')2 fragments in sera of patients allergic to milk.

Colostral G immunoglobulins (IgGs) are described in many recent studies as having a beneficial effect for the treatment of viral, bacterial and parasitic diarrhea in animals and humans. The specific IgE titers to bovine colostral IgG, to bovine serum IgG, and to F(ab')2 fragments of IgG were immunoenzymatically quantified in sera of patients allergic to milk, to statistically evaluate and compare their relative immunoreactivity towards these purified antigens. The results clearly indicated that 36% of the population tested was potentially allergic to colostral IgG, and serum IgG globally elicited significantly lower IgE titers. The F(ab')2 fragments lead to a significantly decreased immunoreactivity as compared to colostral IgG. This study shows the interesting use of peptic hydrolysis of IgG in producing fragments with preserved therapeutic immunoactivity and reduced potential allergenicity.

Human cationic and anionic trypsins: differences of interaction with alpha 1-proteinase inhibitor.

Human cationic (trypsin 1) and anionic (trypsin 2) trypsins were obtained by controlled activation of purified trypsinogens 1 and 2, respectively. The interactions of trypsin 1 and trypsin 2 with human alpha 1-proteinase inhibitor (alpha 1PI) were analysed and compared by studies in vitro. The enzymatic activity and inhibitory capacity measurements were assessed using Glp-Gly-Arg-Nan as substrate. The association rate constants showed that the inhibition of trypsin 2 occurred more than 10 times faster than that of trypsin 1. The equimolar complexes obtained between either trypsin and alpha 1PI were visualized by electrophoresis followed by immunoblotting. The inhibition of the two trypsins was temporary i.e. the complexes trypsin 1-alpha 1PI and trypsin 2-alpha 1PI broke down with time yielding inactive alpha 1PI (Mr 50,000) and active enzyme. But the stability time for trypsin 1-alpha 1PI was much larger than that of trypsin 2-alpha 1PI. In vivo, alpha 1PI is not able to control the activity of trypsin 1 except when alpha 2-macroglobulin (alpha 2M) is already saturated. According to the delay times of inhibition calculated from normal concentrations in serum, alpha 1PI inhibits trypsin 2 as fast as alpha 2M inhibits trypsin 1. These results suggest that a significant role can be assigned to alpha 1PI in the inhibition of trypsin 2 in physiological conditions and of trypsin 1 in pathological ones.

"In vivo" and "in vitro" inhibition of human pancreatic chymotrypsin A by serum inhibitors.

The interaction of human pancreatic chymotrypsin A with serum inhibitors was assessed by enzyme immunoassay, enzymatic activity and inhibitory capacity measurements and electrophoretic analyses. In normal serum, chymotrypsin A was detected in four forms: one form (Mr approximately equal to 25,000) which might be chymotrypsinogen A and three forms complexed to the main inhibitors present in serum, alpha 2-macroglobulin (alpha 2-M), alpha 1-proteinase inhibitor (alpha 1-PI) and alpha 1-antichymotrypsin (alpha 1-Achy). As chymotrypsin A remains to 90% active when bound to alpha 2-M, the chymotrypsin A/alpha 2-M complex was quantified by an enzymatic assay. The kinetic parameters of the interaction of chymotrypsin A with alpha 1-PI and alpha 1-Achy were determined. Using these data the partition of chymotrypsin A between the different inhibitors in serum was calculated. In acute pancreatitis, the chymotrypsin A plasma level follows the progression of the disease and in this case as well as in normal serum alpha 1-PI is the major antagonist of chymotrypsin A.

Human serum alpha 1-antichymotrypsin is an inhibitor of pancreatic elastases.

Incubation of human serum alpha 1-antichymotrypsin with human pancreatic elastase 2 or porcine pancreatic elastase results in the complete inhibition of each enzyme as determined by spectrophotometric assays. alpha 1-Antichymotrypsin reacts much more rapidly with the human than with the porcine enzyme. The inhibitor: enzyme molar ratio, required to obtain full inhibition of enzymatic activity, is equal to 1.25/1 when alpha 1-antichymotrypsin reacts with human pancreatic elastase 2 while it is markedly higher with porcine pancreatic elastase (5.5/1). Patterns obtained by SDS/polyacrylamide gel electrophoresis of the reaction products show the formation with both enzymes of an equimolar complex (Mr near 77 000) and the release of a fragment migrating as a peptide of Mr near 5000. Moreover a free proteolytically modified form of alpha 1-antichymotrypsin, electrophoretically identical with that obtained in the reaction with cathepsin G or bovine chymotrypsin, is produced in the reaction with each elastase but in a much greater amount when alpha 1-antichymotrypsin reacts with porcine elastase than with human elastase. As a consequence of our findings, the specificity of alpha 1-antichymotrypsin, so far limited to the inhibition of chymotrypsin-like enzymes from pancreas and leukocyte origin, has to be extended to the two pancreatic elastases investigated in this work. A contribution of alpha 1-antichymotrypsin to the regulatory balance between plasma inhibitors and human pancreatic elastase 2 in pancreatic diseases is suggested.

Interaction of human alpha 1-proteinase inhibitor with human leukocyte cathepsin G.

Interaction of human plasma alpha 1-proteinase inhibitor (alpha 1-PI) with human leukocyte cathepsin G was assessed by proteinase inhibitory capacity assays and electrophoretic analyses. Only a part of purified alpha 1-PI formed a 1 : 1 complex (Mr = 74 000) with leukocyte cathepsin G. The formation of this complex was accompanied by the appearance of a great amount of a free, proteolytically modified form of alpha 1-PI (Mr = 50 000) which had lost its inhibitory capacity. The complex was unstable with time and the only dead end product observed was a modified, inactive form of alpha 1-PI. During the breakdown of the complex, no release of active enzyme could be measured by spectrophotometric assays. In spite of the fact that the equimolarity of the complex was convincingly demonstrated, studies of the alpha 1-PI-cathepsin G reaction showed that total inhibition of this proteinase needed a large molar excess of alpha 1-PI. Nevertheless, alpha 1-PI acts as an efficient "suicide inhibitor" since no cathepsin G recovery was ever found.