A Glucose binding lectin from Leucaena leucocephala seeds and its mitogenic activity against human lymphocytes.

Lectins are a specialized group of proteins with immense biological properties and applications. This study describes the purification and characterization of a lectin from Leucaena leucocephala seeds, a plant belonging to the Fabaceae family. Leucaena leucocephala lectin (LLL) was purified by a two-step purification method involving DEAE-cellulose anion exchange chromatography and Sephadex G-75 size exclusion chromatography. The isolated lectin displayed a high haemagglutination titre upon treatment with rabbit erythrocytes. SDS-PAGE and Reverse-Phase High performance liquid chromatography (RP-HPLC) analysis experimentally revealed the presence of three bands corresponding to 37, 27 and 20 kDa indicating the presence of isolectins. Periodic Acid Schiff's (PAS) staining of LLL confirmed the presence of glycoprotein. Various biochemical parameters were analysed to study its effect on the haemagglutination activity. Sugar inhibition studies experimentally revealed that Glucose was the most potent inhibitor. Fluorescence spectrometric analysis of LLL and Glucose indicated a strong interaction with an association constant of 0.159 × 103 M-1. Circular Dichroism spectroscopy indicated a higher alpha helical content (25.27%). LLL was observed to possess mitogenic activity against Peripheral blood mononuclear cells (PBMC). The present investigation reports the isolation of a novel lectin from this plant which could contribute towards the diagnostic studies of certain diseases and for its therapeutic potential.

Purification of a potent mitogenic homodimeric Penicillium griseoroseum lectin and its characterisation.

Penicillium griseoroseum lectin was 80-fold purified by successive DEAE Sepharose anion exchange and Sephadex G-100 gel permeation chromatography. P. griseoroseum lectin exhibited haemagglutination activity towards protease-treated rabbit erythrocytes. It showed specificity towards various carbohydrates such as d-mannose, N-acetyl-d-glucosamine, mucins, and so forth. P. griseoroseum lectin was found as a glycoprotein with glycan content of 4.33%. Purified P. griseoroseum lectin is homodimeric having a molecular mass of 57 kDa with subunit molecular mass of 28.6 kDa. Haemagglutination activity of purified P. griseoroseum lectin was completely stable from 25°C to 35°C at a pH range of 6-7.5. Lectin activity was not influenced by divalent metal ions and denaturants. P. griseoroseum lectin manifested mitogenicity towards mice splenocytes and activity reached a peak at 75 µg/ml of lectin concentration. P. griseoroseum lectin in microgram concentrations stimulated proliferation of mice splenocytes. Thus, P. griseoroseum lectin exhibits potential mitogenicity, which can be exploited for further biomedical applications.

Purification of recombinant human fibroblast growth factor 13 in E. coli and its molecular mechanism of mitogenesis.

Fibroblast growth factor (FGF) 13, a member of the FGF11 subfamily, is a kind of intracrine protein similar to other family members including FGF11, FGF12, and FGF14. Unlike classical FGF, FGF13 exerts its bioactivities independent of fibroblast growth factor receptors (FGFRs). However, the effect of exogenous administration of FGF13 still remains further investigated. In the present study, we established an Escherichia coli expression system for the large-scale production of FGF13 and then obtained two isoform proteins including recombinant human FGF13A (rhFGF13A) and rhFGF13B with a purity greater than 90% by column chromatography, respectively. Otherwise, soluble analysis indicated that both rhFGF13A and rhFGF13B expressed in E. coli BL21 (DE3) pLysS were soluble. Furthermore, cellular-based experiments demonstrated that rhFGF13A, rather than rhFGF13B, could promote the proliferation of NIH3T3 cells in the presence of heparin. Mechanistically, the mitogenic effect of FGF13 was mediated by activation of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK), but not p38. Moreover, blockage of FGFRs also significantly attenuated the mitogenic effects of rhFGF13A, implying that FGFRs are still related to FGF13. Thus, our research shows that exogenous FGF13 can act as secreted FGF to participate in cell signal transmission and heparin is still required as an ancillary cofactor for the mitogenic effects of FGF13, which may help people to discover more potential functions of FGF13 in cell life activities.

Purification and characterization of a mitogenic lectin from Penicillium duclauxii.

Lectins are proteins/glycoproteins of non-immune origin which interact specifically and non-covalently with carbohydrate moieties on the cell surface. In this study, a lectin was purified from Penicillium duclauxii by ion-exchange chromatography on DEAE-Sepharose and gel filtration chromatography on a Sephadex G-100 column. An overall recovery of 94.11% and 60-fold purification was achieved. The purified lectin had a molecular weight of 54.9 kDa and was found to be heterogeneous as revealed by double band of sub-units with molecular mass of 21.13 kDa and 33.26 kDa, under reducing conditions. It is a glycoprotein with carbohydrate content of 3.95%. Lectin induced haemagglutination of erythrocytes was inhibited strongly by glycoproteins such as bovine submaxillary mucin, porcine stomach mucin and fetuin. The maximum haemagglutinating activity of P. duclauxii lectin was maintained after incubation at a temperature and pH range of 20-35 °C and 6.0-8.0, respectively. The haemagglutinating activity of P. duclauxii lectin was unaffected by EDTA and various metal ions. The purified P. duclauxii lectin exhibited maximum mitogenic activity towards mouse splenocytes at a concentration of 75 µg/mL. This manuscript reports a novel lectin from P. duclauxii with potent mitogenic activity towards mouse splenocytes.

Purification and Characterization of a Lectin from Green Split Peas (Pisum sativum).

Lectins have captured the attention of a large number of researchers on account of their various exploitable activities, including antitumor, immunomodulatory, antifungal, as well as HIV reverse transcriptase inhibitory activities. A mannose/glucose-specific lectin was isolated from green split peas (a variety of Pisum sativum) and characterized. The purification step involved anion-exchange chromatography on a DEAE-cellulose column, cation-exchange chromatography on an SP-Sepharose column, and gel filtration by fast protein liquid chromatography (FPLC) on Superdex 200. The purified lectin had a native molecular mass of around 50 kDa as determined by size exclusion chromatography. It appeared as a heterotetramer, composed of two distinct polypeptide bands with a molecular mass of 6 and 19 kDa, respectively, in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The N-terminal sequence of green split pea lectin shows some degree of homology compared to lectins from other legume species. Its hemagglutinating activity was inhibited by glucose, mannose, and sucrose, and attenuated at pH values higher than 12 or lower than 3. Hemagglutinating activity was preserved at temperatures lower than 80 °C. The lectin did not show antifungal activity toward fungi including Fusarium oxysporum, Botrytis cinerea, and Mycosphaerella arachidicola. Green split pea lectin showed a mitogenic effect toward murine splenocytes and could inhibit the activity of HIV-1 reverse transcriptase.

Purification, characterization, and mitogenic potential of a mucin-specific mycelial lectin from Aspergillus sparsus.

Lectins are carbohydrate binding proteins or glycoproteins that bind reversibly to specific carbohydrates present on the apposing cells, which is responsible for their ability to agglutinate red blood cells, lymphocytes, fibroblasts, etc. Due to their carbohydrate specificity, lectins have been used for purification and characterization of glycoproteins like antibodies, cytokines, tumor-associated glycoproteins, hormones, inhibitors, growth factors, various enzymes, membrane proteins (receptors), or even toxins and viruses. In the present study, a mycelial lectin from Aspergillus sparsus was purified, characterized, and evaluated for its mitogenic potential. Lectin could be effectively purified 17.8-fold in a single-step using affinity chromatography on mucin-sepharose column. Lectin migrated as a single band in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) with an apparent molecular mass of 100.2 kDa. Lectin showed pH optima of 6.5-8.0, and optimum temperature was determined to be 20-30 °C. Lectin was stable within a pH range of 5.5-10.0 and showed fairly good thermostability. Lectin activity was unaffected in the presence of EDTA, while activity reduced upon interaction with denaturants. MTT assay revealed strong mitogenic potential of A. sparsus lectin at a concentration up to 100 µg/ml.

Purification and characterization of a mucin specific mycelial lectin from Aspergillus gorakhpurensis: application for mitogenic and antimicrobial activity.

BACKGROUND: Lectins are carbohydrate binding proteins or glycoproteins that bind reversibly to specific carbohydrates present on the apposing cells, which are responsible for their ability to agglutinate red blood cells, lymphocytes, fibroblasts, etc. Interest in lectins has been intensified due to their carbohydrate specificity as they can be valuable reagents for the investigation of cell surface sugars, purification and characterization of glycoproteins. The present study reports the purification, characterization and evaluation of mitogenic and antimicrobial potential of a mycelial lectin from Aspergillus gorakhpurensis. METHODS: Affinity chromatography on mucin-sepharose column was carried out for purification of Aspergillus gorakhpurensis lectin. The lectin was characterized for physico-chemical parameters. Mitogenic potential of the lectin was evaluated against splenocytes of Swiss albino mice by MTT assay. Antimicrobial activity of the purified lectin has also been evaluated by disc diffusion assay. RESULTS: Single-step affinity purification resulted in 18.6-fold purification of the mycelial lectin. The molecular mass of the lectin was found to be 70 kDa and it was composed of two subunits of 34.8 kDa as determined by gel filtration chromatography, SDS-PAGE and MALDI-TOF analysis. pH optima of the lectin was found to be 6.5-9.5, while optimum temperature for lectin activity was 20-30 °C. Lectin was stable within a pH range of 7.0-10.5 and showed fair thermostability. EDTA did not affect lectin activity whereas it was found susceptible to the denaturants tested. MTT assay revealed strong mitogenic potential of A. gorakhpurensis lectin at a concentration upto 150 µg/mL. Antimicrobial activity assay showed its potent antibacterial activity against Bacillus cereus, Staphylococcous aureus and Escherichia coli and marginal antifungal activity against Saccharomyces cerevisiae. CONCLUSION: This is the first report on the mitogenic and antimicrobial potential of Aspergillus gorakhpurensis lectin. The results will provide useful guidelines for further research in clinical applications of this lectin.

Solid-phase N-terminus PEGylation of recombinant human fibroblast growth factor 2 on heparin-sepharose column.

Recombinant fibroblast growth factor-2 (FGF-2) has been extensively studied and used in several clinical applications including wound healing, bone regeneration, and neuroprotection. Poly(ethylene glycol) (PEG) modification of recombinant human FGF-2 (rhFGF-2) in solution phase has been studied to increase the in vivo biostabilities and therapeutic potency. However, the solution-phase strategy is not site-controlled and the products are often not homogeneous due to the generation of multi-PEGylated proteins. In order to increase mono-PEGylated rhFGF-2 level, a novel solid-phase strategy for rhFGF-2 PEGylation is developed. RhFGF-2 proteins were loaded onto a heparin-sepharose column and the PEGylaton reaction was carried out at the N-terminus by PEG20 kDa butyraldehyde through reductive alkylation. The PEGylated rhFGF-2 was purified to near homogeneity by SP sepharose anion-exchange chromatography and the purity was more than 95% with a yield of mono-PEGylated rhFGF-2 of 58.3%, as confirmed by N-terminal sequencing and MALDI-TOF mass spectrometry. In vitro biophysical and biochemical measurements demonstrated that PEGylated rhFGF-2 has an unchanged secondary structure, receptor binding activity, cell proliferation, and MAP kinase stimulating activity, and an improved bio- and thermal stability. Animal assay showed that PEGylated rhFGF-2 has an increased half-life and reduced immunogenicity. Compared to conventional solution-phase PEGylation, the solid-phase PEGylation is advantageous in reaction time, production of mono-PEGylated protein, and improvement of biochemical and biological activity.

Mitogenic activity of CEL-I, an N-acetylgalactosamine (GalNAc)-specific C-type lectin, isolated from the marine invertebrate Cucumaria echinata (Holothuroidea).

An N-acetylgalactosamine (GalNAc)-specific Ca(2+)-dependent lectin (C-type lectin), isolated from the marine invertebrate Holothuroidea (Cucumaria echinata), CEL-I, showed potent mitogenic activity toward normal mouse spleen cells. The mitogenic activity of CEL-I, which reached a maximum at 100 microg/ml, was inhibited by GalNAc in a concentration-dependent manner. The mitogenic effect of CEL-I at 10 microg/ml on T cell- enriched splenocytes was at a similar level due to a well-known T cell mitogen, concanavalin A (Con A), at 10 microg/ml. Furthermore, CEL-I evoked a mitogenic response from nude mouse spleen cells, while no significant effects of Con A on this cell population were observed over a wide range of concentrations. These results suggest that CEL-I is a potent mitogenic lectin with the ability to stimulate both T and B cells.

Characterisation of a haemagglutinin from Hokkaido red bean (Phaseolus vulgaris cv. Hokkaido red bean).

BACKGROUND: A haemagglutinin was purified from Japanese Hokkaido red beans (Phaseolus vulgaris cv. Hokkaido red bean) with a procedure that included three chromatographic media. RESULTS: Haemagglutinating activity was adsorbed on DEAE cellulose, Affi-gel blue gel and Mono S. The pure haemagglutinin was a homodimer and each subunit was around 30 kDa in molecular mass. The haemagglutinating activity of this agglutinin could not be inhibited by a variety of simple sugars at 200 mmol L(-1) concentration including alpha-L-fucose, D(+)-galactose, D(+)-glucose, D(+)-glucosamine, D(-)galactosamine, galacturonic acid, (+)-lactose, D(+)-melibose, L(-)-mannose, D(+)-mannose, D-mannosamine, D(+)-raffinose, L-rhamnose, (+)-xylose and galacturonic acid. The haemagglutinating activity was fully retained at pH 4-11 and at 0-80 degrees C, but was completely lost at extreme pH values (0-2 and 13-14) and at very high temperatures (90 degrees C and 100 degrees C). The haemagglutinin exhibited a weak mitogenic activity toward mouse splenocytes, a stronger anti-proliferative activity than Con A toward HepG2 (human hepatoma) cells and inhibited >80% of HIV-1 reverse transcriptase inhibitory activity at 3.3 micromol L(-1). It was devoid of anti-fungal activity. CONCLUSION: Hokkaido red bean haemagglutinin possesses a potent anti-proliferative effect on HepG2 cells.

A novel lectin with highly potent antiproliferative and HIV-1 reverse transcriptase inhibitory activities from cicada (Cicada flammata).

A dimeric lectin with a molecular weight of 60 kDa and high hemagglutinating activity was isolated from dried cicadas. It was adsorbed on Q-Sepharose and unadsorbed on Affi-Gel Blue gel. Its hemagglutinating activity was stable up to 55 degrees C and between pH 2 and 13. The activity was inhibited by glucuronic acid and raffinose, K(+) ions, and Mg(2+) ions. Cicada lectin potently inhibited proliferation of HepG2 hepatoma and MCF 7 breast cancer cells, with an IC(50) value of 0.76 and 0.49 microM, respectively. It potently inhibited HIV-1 reverse transcriptase activity with an IC(50) of 0.36 microM but was devoid of mitogenic activity on spleen cells. Its N-terminal sequence exhibited slight similarity to a conserved hypothetical protein from Culex quinquefasciatus and a gene product from transcript GH19834-RA of Drosophila grimshawi, but there was no resemblance to lectins from other insects, including Drosophila, Sarcophaga, Glossina, and Aedes species.

Purification and characterization of a lectin from Phaseolus vulgaris cv. (Anasazi beans).

A lectin has been isolated from seeds of the Phaseolus vulgaris cv. "Anasazi beans" using a procedure that involved affinity chromatography on Affi-gel blue gel, fast protein liquid chromatography (FPLC)-ion exchange chromatography on Mono S, and FPLC-gel filtration on Superdex 200. The lectin was comprised of two 30-kDa subunits with substantial N-terminal sequence similarity to other Phaseolus lectins. The hemagglutinating activity of the lectin was stable within the pH range of 1-14 and the temperature range of 0-80 degrees C. The lectin potently suppressed proliferation of MCF-7 (breast cancer) cells with an IC(50) of 1.3 microM, and inhibited the activity of HIV-1 reverse transcriptase with an IC(50) of 7.6 microM. The lectin evoked a mitogenic response from murine splenocytes as evidenced by an increase in [3H-methyl]-thymidine incorporation. The lectin had no antifungal activity. It did not stimulate nitric oxide production by murine peritoneal macrophages. Chemical modification results indicated that tryptophan was crucial for the hemagglutinating activity of the lectin.

Large-scale production of biologically active human keratinocyte growth factor-2.

A rapid and efficient expression and purification system has been developed for large-scale production of biologically active recombinant human keratinocyte growth factor-2 (rhKGF-2). The gene encoding human KGF-2 was cloned into the expression vector pET3c and transformed into Escherichia coli BL21(DE3)/pLys S. Under optimal conditions in a 30-l fermentor, the average bacterial yield and the average expression level of rhKGF-2 of three batches were up to 732 g and 32%, respectively. The recombinant protein was purified by cation exchange and heparin-affinity chromatography. One hundred and sixty five milligrams of pure rhKGF-2 was achieved per liter culture. A preliminary biochemical characterization of purified rhKGF-2 was performed by Western blotting and mitogenic activity analysis, and the results demonstrated that purified rhKGF-2 could react with anti-human KGF-2 antibody and stimulate the proliferation of HaCat cells.

Antiproliferative effect of T/Tn specific Artocarpus lakoocha agglutinin (ALA) on human leukemic cells (Jurkat, U937, K562) and their imaging by QD-ALA nanoconjugate.

T/Tn specificity of Artocarpus lakoocha agglutinin (ALA), isolated from the seeds of A. lakoocha (Moraceae) fruit and a heterodimer (16 kD and 12 kD) of molecular mass 28 kD, was further confirmed by SPR analysis using T/Tn glycan containing mammalian glycoproteins. N-terminal amino acid sequence analysis of ALA showed homology at 15, 19-21, 24-27, and 29 residues with other lectin members of Moraceae family viz., Artocarpus integrifolia (jacalin) lectin, Artocarpus hirsuta lectin, and Maclura pomifera agglutinin. It is mitogenic to human PBMC and the maximum proliferation was observed at 1 ng/ml. It showed an antiproliferative effect on leukemic cells, with the highest effect toward Jurkat cells (IC(50) 13.15 ng/ml). Synthesized CdS quantum dot-ALA nanoconjugate was employed to detect the expression of T/Tn glycans on Jurkat, U937, and K562 leukemic cells surfaces as well as normal lymphocytes by fluorescence microscopy. No green fluorescence was observed with normal lymphocytes indicating that T/Tn determinants, which are recognized as human tumor associated structures were cryptic on normal lymphocyte surfaces, whereas intense green fluorescent dots appeared during imaging of leukemic cells, where such determinants were present in unmasked form. The above results indicated that QD-ALA nanoconjugate is an efficient fluorescent marker for identification of leukemic cell lines that gives rise to high quality images.

Mitogenic component in polar lipid-enriched Anaplasma phagocytophilum membranes.

Human granulocytic anaplasmosis is an emerging tick-borne disease caused by Anaplasma phagocytophilum. A. phagocytophilum cells activate Toll-like receptor 2 signaling and possess mitogenic activity, and A. phagocytophilum infection in vivo activates NKT cells unrelated to major surface protein 2 (Msp2) hypervariable region expression. Thus, we hypothesized that lipoprotein or glycolipid components of A. phagocytophilum membranes could be important triggers of the innate immune response and immunopathology. A. phagocytophilum membranes depleted of Msp2 and protein antigens enhanced the proliferation of naïve mouse splenocytes beyond that of untreated membranes. Protein-depleted and polar lipid-enriched membranes from low-passage A. phagocytophilum cultures enhanced naïve splenocyte lymphoproliferation to a much greater degree than did these fractions from high-passage cultures of bacterial membranes (1.8- to 3.7-fold for protein-depleted fractions and 4.8- to > or =17.7-fold for polar lipid-enriched fractions). These results support the hypothesis that components that are enriched among polar lipids in the A. phagocytophilum membrane stimulate innate immune cell proliferation, possibly activating NKT cells that link innate and adaptive immunity, and immunopathology.

The structure of CMS2MS2, a mitogenic protein isolated from Carica candamarcensis.

In a recent study we showed that two proteinases (CMS2MS2 and CMS2MS3) from Carica candamarcensis enhance mammalian cell proliferation. The aim of the present study is the determination of the primary structure of CMS2MS2 and prediction of its three-dimensional structure. The protein contains 214 residues, including the catalytic triad composed of Cys(25), His(159), and Asn(175). A phylogenetic tree analysis demonstrated that CMS2MS2 ranks closer to chymopapain than to papain. The overall predicted three-dimensional structure is similar to proteinases from the papain family. These results suggest that minor structural differences within CMS2MS2 must account for its proliferative action.

A mannose-specific tetrameric lectin with mitogenic and antibacterial activities from the ovary of a teleost, the cobia (Rachycentron canadum).

A tetrameric lectin, with hemagglutinating activity toward rabbit erythrocytes and with specificity toward D-mannosamine and D(+)-mannose, was isolated from the ovaries of a teleost, the cobia Rachycentron canadum. The isolation protocol comprised ion exchange chromatography on CM-cellulose and Q-Sepharose, ion exchange chromatography by fast protein liquid chromatography (FPLC) on Mono Q, and finally gel filtration by FPLC on Superose 12. The lectin was adsorbed on all ion exchangers used. It exhibited a molecular mass of 180 kDa in gel filtration on Superose 12 and a single 45-kDa band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, indicating that it is a tetrameric protein. The hemagglutinating activity of the lectin was stable up to 40 degrees C and between pH 4 and pH 10. All hemagglutinating activity disappeared at 60 degrees C and at pH 1 and pH 13. The hemagglutinating activity was doubled in the presence of 0.1 microM FeCl3. The lectin exerted antibacterial activity against Escherichia coli with 50% inhibition at 250 microg. There was no antifungal activity toward Coprinus comatus, Fusarium oxysporum, Mycosphaerella arachidicola, and Rhizoctonia solani at a dose of 300 microg. The lectin exhibited maximal mitogenic response from mouse splenocytes at a concentration of 14 microM.

A lectin with antifungal and mitogenic activities from red cluster pepper (Capsicum frutescens) seeds.

A monomeric mannose/glucose-binding lectin, with a molecular mass of 29.5 kDa and an N-terminal sequence GQRELKL showing resemblance to that of the lectin-like oxidized low-density lipoprotein receptor from the rabbit, has been isolated from the seeds of red cluster pepper Capsium frutescens L. var. fasciculatum. The protocol involved anion exchange chromatography on diethylamino ethanol-cellulose and Q-Sepharose and fast protein liquid chromatography on Mono Q. Its hemagglutinating activity toward rabbit erythrocytes was inhibited by D: -mannose and glucose, specifically. The activity was stable from 0 to 40 degrees C, reached a maximum at pH 7 and 8, and was potentiated by Ca2+ and Mn2+ ions. The lectin showed strong mitogenic activity toward spleen cells isolated from BALB/c mice. The mitogenic activity, which reached a peak at a lectin concentration of 0.27 microM, was inhibited specifically by D(+)-mannose. The lectin was capable of inhibiting the germination of Aspergillus flavus and Fusarium moniliforme spores and hyphal growth in the two fungi.

In vitro immunomodulatory activities of a newly concocted traditional Chinese medicine formula: VI-28.

Previous studies have suggested that Vigconic VI-28, an anti-aging traditional Chinese medicine (TCM) formula containing Radix Ginseng and Cornu Cervi Pantotrichum, possesses immunological efficacy. This in vitro study further investigated the immunomodulatory effects of the hot water extracts of VI-28. The study included (1) colorimetric 5-bromo-2'-deoxy-uridine proliferation ELISA for estimating mitogenicity in human peripheral blood mononuclear cells (PBMC), (2) immunofluorescence staining for measuring the expression of IL-2 receptor alpha (CD25) on lymphocytes, (3) cytometric bead array (CBA) for quantifying cytokine liberation from PBMC, and (4) intracellular immunophenotyping for macrophage phagocytosis and hydrogen peroxide (H(2)O(2)) production from monocytes. The results demonstrated that VI-28 (1) could dose-dependently inhibited the proliferation of unstimulated and lipopolysaccharide-activated PBMC but enhanced the proliferation of phytohemagglutinin-activated PBMC at concentrations of <1 mg/mL, (2) significantly augmented the expression of CD25 on lymphocytes at concentrations of 0.4 mg/mL or above (p < 0.05), (3) dose dependently (0.1-1.0 mg/mL) activated macrophage phagocytosis and monocyte synthesis of H(2)O(2) and (4) significantly increased the production of cytokines IL-8, IL-10, IL-12 and IL-1beta at various concentrations of VI-28 (p < 0.05). The results suggest that VI-28 is a potential immunomodulator which probably acts through the activation of lymphocytes and monocytes.

A lectin with some unique characteristics from the samta tomato.

A lectin, with a molecular mass of 79 kDa, and with specificity toward rhamnose and O-nitrophenyl-beta-D-galactopyranoside, was isolated from samta tomato fruits. The procedure entailed ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on CM-cellulose and gel filtration by fast protein liquid chromatography on Superdex 75. The lectin was unadsorbed on DEAE-cellulose but adsorbed on Affi-gel blue gel and CM-cellulose. The lectin was stable up to 70 degrees C. The lectin activity was potentiated by NaOH solutions (25-100 mM), but was reduced by 50 and 100 mM HCl solutions. The activity of the lectin was reduced in the presence of CaCl(2), MgCl(2) and ZnCl(2), but was potentiated by 5 and 10 mM AlCl(3) solutions. The lectin stimulated the mitogenic response in mouse splenocytes and inhibited human immunodeficiency virus-1 reverse transcriptase with an IC(50) of 6.2 microM.