Multiple epoxide hydrolases in Alternaria alternata f. sp. lycopersici and their relationship to medium composition and host-specific toxin production.

The production of Alternaria alternata f. sp. lycopersici host-specific toxins (AAL toxins) and epoxide hydrolase (EH) activity were studied during the growth of this plant-pathogenic fungus in stationary liquid cultures. Media containing pectin as the primary carbon source displayed peaks of EH activity at day 4 and at day 12. When pectin was replaced by glucose, there was a single peak of EH activity at day 6. Partial characterization of the EH activities suggests the presence of three biochemically distinguishable EH activities. Two of them have a molecular mass of 25 kDa and a pI of 4.9, while the other has a molecular mass of 20 kDa and a pI of 4.7. Each of the EH activities can be distinguished by substrate preference and sensitivity to inhibitors. The EH activities present at day 6 (glucose) or day 12 (pectin) are concomitant with AAL toxin production.     

Stimulation of the production of extracellular pectinolytic activities of Aspergillus sp. by galacturonic acid and glucose addition

We studied the effect of the addition of galacturonic acid and of glucose on the production of the pectinolytic activities by Aspergillus sp. The results showed that a differential response in the production of the activities was produced. The production of the pectinolytic activity as measured by reducing groups was not negatively affected when low concentrations of eithr glucose or galacturonic acid were added to growing pectin containing cultures of Aspergillus sp. regardless of the time of addition. The production of the activity, measured by viscosimetry, was stimulated by addition of galacturonic acid at 24 h, suggesting that galacturonic acid participates in the induction of pectinolytic activities of Aspergillus sp. When the addition was made at t = 0, the increase in pH seems to affect the production of this activity. The addition of glucose at 24 h had no effect on the production of the viscosimetric activity; however, catabolic repression was observed upon the addition at t = 0. The production of both pectinolytic activities was strongly repressed when glucose was added at high concentration and was affected less when galacturonic acid was added at the same high concentration.     

Purification and characterization of two isozymes of polygalacturonase from Botrytis cinerea. Effect of calcium ions on polygalacturonase activity

The phytopathogenic fungus Botrytis cinerea produces a set of polygalacturonases (PGs) which are involved in the enzymatic degradation of pectin during plant tissue infection. Two polygalacturonases secreted by B. cinerea in seven-day-old liquid culture were purified to apparent homogeneity by chromatography. PG I was an exopolygalacturonase of molecular weight 65 kDa and pI 8.0 and PG II was an endopolygalacturonase of 52 kDa and pI 7.8. Enzymatic activity of PG I and PG II was partially inhibited by 1 mM CaCl₂, probably by calcium chelation of polygalacturonic acid, the substrate of the enzyme.     

Metal binding activity of pectin isolated from seagrass Zostera marina and its derivatives

Low esterified pectin was isolated from the seagrass Zostera marina. Dynamics of the isolation process for the pectin from this seagrass was investigated. Two pectin derivatives: galacturonide (A) with molecular weight 30.55 kDa and galacturonide (B) with molecular weight 3.94 kDa were obtained using acidic hydrolysis of the native pectin from Zostera marina. Molecular weight parameters (Mw, Mn, Mw/Mn) of this pectin and its derivatives as well as of commercial apple pectin were determined using gel-filtration chromatography method. Comparative assessment of Cd²⁺, Pb²⁺, Y³⁺-binding activity of the native Zostera pectin, galacturonides A and B, and commercial apple pectin was performed. The results showed that galacturonide A with molecular weight 30.55 kDa possesses highest metal-binding capacity and may be considered as a candidate for development of medicines with metal-binding activity.     

Purification, Characterization, and Molecular Analysis of Thermostable Cellulases CelA and CelB from Thermotoga neapolitana

Two thermostable endocellulases, CelA and CelB, were purified from Thermotoga neapolitana. CelA (molecular mass, 29 kDa; pI 4.6) is optimally active at pH 6.0 at 95°C, while CelB (molecular mass, 30 kDa; pI 4.1) has a broader optimal pH range (pH 6.0 to 6.6) at 106°C. Both enzymes are characterized by a high level of activity (high V_max value and low apparent K_m value) with carboxymethyl cellulose; the specific activities of CelA and CelB are 1,219 and 1,536 U/mg, respectively. With p-nitrophenyl cellobioside the V_max values of CelA and CelB are 69.2 and 18.4 U/mg, respectively, while the K_m values are 0.97 and 0.3 mM, respectively. The major end products of cellulose hydrolysis, glucose and cellobiose, competitively inhibit CelA, and CelB. The K_i values for CelA are 0.44 M for glucose and 2.5 mM for cellobiose; the K_i values for CelB are 0.2 M for glucose and 1.16 mM for cellobiose. CelB preferentially cleaves larger cellooligomers, producing cellobiose as the end product; it also exhibits significant transglycosylation activity. This enzyme is highly thermostable and has half-lives of 130 min at 106°C and 26 min at 110°C. A single clone encoding the celA and celB genes was identified by screening a T. neapolitana genomic library in Escherichia coli. The celA gene encodes a 257-amino-acid protein, while celB encodes a 274-amino-acid protein. Both proteins belong to family 12 of the glycosyl hydrolases, and the two proteins are 60% similar to each other. Northern blots of T. neapolitana mRNA revealed that celA and celB are monocistronic messages, and both genes are inducible by cellobiose and are repressed by glucose.     

Targeted Mutants of Cochliobolus carbonum Lacking the Two Major Extracellular Polygalacturonases

The filamentous fungus Cochliobolus carbonum produces endo-α1,4-polygalacturonase (endoPG), exo-α1,4-polygalacturonase (exoPG), and pectin methylesterase when grown in culture on pectin. Residual activity in a pgn1 mutant (lacking endoPG) was due to exoPG activity, and the responsible protein has now been purified. After chemical deglycosylation, the molecular mass of the purified protein decreased from greater than 60 to 45 kDa. The gene that encodes exoPG, PGX1, was isolated with PCR primers based on peptide sequences from the protein. The product of PGX1, Pgx1p, has a predicted molecular mass of 48 kDa, 12 potential N-glycosylation sites, and 61% amino acid identity to an exoPG from the saprophytic fungus Aspergillus tubingensis. Strains of C. carbonum mutated in PGX1 were constructed by targeted gene disruption and by gene replacement. Growth of pgx1 mutant strains on pectin was reduced by ca. 20%, and they were still pathogenic on maize. A double pgn1/pgx1 mutant strain was constructed by crossing. The double mutant grew as well as the pgx1 single mutant on pectin and was still pathogenic despite having less than 1% of total wild-type PG activity. Double mutants retained a small amount of PG activity with the same cation-exchange retention time as Pgn1p and also pectin methylesterase and a PG activity associated with the mycelium. Continued growth of the pgn1/pgx1 mutant on pectin could be due to one or more of these residual activities.     

Purification and characterization of two isozymes of polygalacturonase from Botrytis cinerea. Effect of calcium ions on polygalacturonase activity

The phytopathogenic fungus Botrytis cinerea produces a set of polygalacturonases (PGs) which are involved in the enzymatic degradation of pectin during plant tissue infection. Two polygalacturonases secreted by B. cinerea in seven-day-old liquid culture were purified to apparent homogeneity by chromatography. PG I was an exopolygalacturonase of molecular weight 65 kDa and pI 8.0 and PG II was an endopolygalacturonase of 52 kDa and pI 7.8. Enzymatic activity of PG I and PG II was partially inhibited by 1 mM CaCl2, probably by calcium chelation of polygalacturonic acid, the substrate of the enzyme.     

A lectin with mycelia differentiation and antiphytovirus activities from the edible mushroom Agrocybe aegerita

A lectin named AAL has been purified from the fruiting bodies of the edible mushroom Agrocybe aegerita. AAL consisted of two identical subunits of 15.8 kDa, its pI was about 3.8 determined by isoelectric focusing, and no carbohydrate was discerned. Being treated by pyrogultamate aminopeptidase, the blocked N-terminus of AAL was sequenced as QGVNIYNI. AAL agglutinated human and animal erythrocytes regardless of blood type or animal species. Its hemagglutinating activity was unaffected by acid or alkali treatment and demetalization or addition of divalent metals Mg(2+), Ca(2+) and Zn(2+). AAL was toxic to mice: its LD50 was 15.85 mg per kilogram body weight by intraperitoneal injection. In this study, two novel activities of AAL were proved. It showed inhibition activity to infection of tobacco mosaic virus on Nicotiana glutinosa. The result of IEF suggested that AAL attached to TMV particles. Mycelia differentiation promotion was the other interesting activity. AAL promoted the differentiation of fruit body primordia from the mycelia of Agrocybe aegerita and Auricularia polytricha. AAL antiserum was prepared and immunologically cross-reactived with several proteins from five other kinds of mushrooms. These results suggested that AAL probably was a representative of a large protein family, which plays important physiological roles in mushroom.     

Culture conditions for the production of pectinolytic enzymes by the white-rot fungus Trametes trogii on a laboratory scale

Different cultural parameters that regulate pectinolytic enzyme production in vitro by Trametes trogii were studied. When grown in a medium containing pectin, T. trogii produced extracellular polymethylgalacturonase, polygalacturonase and pectin lyase but no pectate lyase activity. No significant differences in the maximum enzyme activities measured were observed with the addition of xylan, carboxymethylcellulose or both to the medium containing pectin. The addition of glucose to that medium considerably decreases all the activities studied, and in a medium with glucose as the sole carbon source no galacturonase activity could be measured, and pectin lyase activity was at its minimum. The low synthesis of pectin lyase in cultures containing glucose suggests that this enzyme is constitutive in contrast to the polygalacturonases that were not detected. The increase in pectin concentration stimulated growth and enzyme production. The highest specific activities were attained with the greatest concentration tested (15 g/l). Casamino acids were the best nitrogen source for enzyme production. Maximum growth was measured at pH 3.3; pH values of around 4.5 stimulated enzyme production, but high pectinase activities were also detected in media with more alkaline initial pH values (6.2 for galacturonases and 6.6 for lyases), probably owing to the specific induction of particular isoforms. In the range of 23 to 28°C, good results were obtained in growth as well as in enzyme production. The addition of Tween 80 promoted growth and gave the highest yield of polymethylgalacturonase and pectin lyase (0.37 and 36.2 E.U./ml, respectively). The highest polygalacturonase activity (1.1 E.U/ml) was achieved with polyethylene glycol. Tween 20 and Triton X-100 inhibited growth and pectinase production.     

Influence of pectin and glucose on growth and polygalacturonase production by Aspergillus niger in solid-state cultivation

The solid-state production of endo- and exo-polygalacturonases (PG) by Aspergillus niger was studied in a media containing wheat bran, salts, and different citric pectin and/or glucose concentrations. Kinetic analysis of the process indicated that the formation of PG and the growth of A. niger are associated processes. By increasing citric pectin from 0 to 16% (w/w), the maximum A. niger concentration (X _m) was raised from 94 to 121 mg/g dry medium suggesting that pectin can be used by A. niger as a growth substrate besides its role as an inducer. With 16% (w/w) pectin, 281 U exo-PG/gdm and 152 U endo-PG/gdm were obtained. Otherwise, pectin concentrations from 20 to 30% (w/w) hindered both production and growth. A. niger concentrations of 108–113 mg/gdm were achieved in runs with glucose from 5 to 12% (w/w), whereas at 16 and 20% (w/w) glucose, lower X _m values (ca. 100 mg/gdm) were measured. The addition of glucose to the wheat bran medium, up to 10% (w/w) led to maximum endo-PG titers slightly lower than those found in the absence of glucose. Nevertheless, exo-PG formation in these media was strongly increased and activities over 370 U/gdm were achieved. The results suggest that in experiments with pectin concentrations until 16% (w/w), exo-PG production was repressed by pectin-degradation products although these same substances had favored biomass growth. When glucose concentrations over 10% (w/w) were added to the media, the maximum activities of both enzymes decreased drastically, suggesting that glucose at high concentrations also exerts a repressive effect on PG production.     

Human liver glucuronate 2-sulphatase. Purification, characterization and catalytic properties.

Human glucuronate 2-sulphatase (GAS), which is involved in the degradation of the glycosaminoglycans heparan sulphate and chondroitin 6-sulphate, was purified almost 2,000,000-fold to homogeneity in 8% yield from liver with a four-step six-column procedure, which consists of a concanavalin A-Sepharose/Blue A-agarose coupled step, a DEAE-Sephacel/octyl-Sepharose coupled step, CM-Sepharose chromatography and gel-permeation chromatography. Although more than 90% of GAS activity had a pI of greater than 7.5, other forms with pI values of 5.8, 5.3, 4.7 and less than 4.0 were also present. The pI greater than 7.5 form of GAS had a native molecular mass of 63 kDa. SDS/polyacrylamide-gel-electrophoretic analysis resulted in two polypeptide subunits of molecular mass 47 and 19.5 kDa. GAS was active towards disaccharide substrates derived from heparin [O-(beta-glucuronic acid 2-sulphate)-(1----4)-O-(2,5)-anhydro[1-3H]mannitol 6-sulphate (GSMS)] and chondroitin 6-sulphate [O-(beta-glucuronic acid 2-sulphate-(1----3)-O-(2,5)-anhydro[1-3H]talitol 6-sulphate (GSTS)]. GAS activity towards GSMS and GSTS was at pH optima of 3.2 and 3.0 respectively with apparent Km values of 0.3 and 0.6 microM respectively and corresponding Vmax values of 12.8 and 13.7 mumol/min per mg of protein respectively. Sulphate and phosphate ions are potent inhibitors of enzyme activity. Cu2+ ions stimulated, whereas EDTA inhibited enzyme activity. It was concluded that GAS is required together with a series of other exoenzyme activities in the lysosomal degradation of glycosaminoglycans containing glucuronic acid 2-sulphate residues.     

Pectin Lyase Production by a Penicillium italicum Strain

Growth and concomitant production of an extracellular pectin lyase (PL) [poly(methoxylgalactosiduronate) endolyase; EC 4.2.2.10] were investigated in a group of 16 fungi grown in liquid medium containing pectin as a supplementary carbon source. Culture filtrates of both Penicillium italicum (CECT 2294) and P. expansum (CECT 2275) showed the highest PL activity and contained polygalacturonase but not pectinesterase activity. The effect of the inoculum size, the carbon source (sucrose and glucose syrup), and the presence of pectin on the production of PL by P. italicum was studied. The presence of 2.6 mM glycerophosphate in the culture medium enhanced the appearance of PL but was not inhibitory for the in vitro activity. However, glycerol inhibited the enzyme nearly 50% at such a concentration.     

Purification and chacterization of acid-type phosphatases from a heavy-metal-accumulating Citrobacter sp.

An acid phosphatase from a heavy-metal-accumulating strain of a Citrobacter sp. was resolved into two forms on the basis of their nonbinding (phosphatase I) or binding (phosphatase II) behaviour on the cation-exchange resin SP-Sephadex C50. Both holoenzymes had a molecular mass of 103–108 kDa as determined by Superose Q-6 column chromatography in the presence of 150 mM KCl and a subunit molecular mass of 27 kDa as determined by SDS-PAGE; the enzyme was tetrameric. Both enzymes had a pI ≈ 9.0 and were immunologically cross-reactive. There were minor differences in amino acid composition and in peptide maps following tryptic digest. The pH optimum for phosphatases I and II was 5.5 and 6.25, respectively; phosphatase II alone retained activity at pH values up to 9.0. Phosphatase I was more resistant to mechanical shear, γ-irradiation, high temperature, and toxins (F^– and formaldehyde). Glycerol increased the thermostability of both enzymes, particularly the more thermosensitive phosphatase II. Phosphatase II had a lower K _m and a lower V _max for glycerol 2-phosphate hydrolysis. The production of enzyme isoforms is a phenomenon similar to that described previously for the alkaline phosphatase of Escherichia coli, where the isoforms relate to precursive and final processed forms of the enzyme. Acid phosphatase is physiologically distinct, with a role that is still obscure but that may relate to cellular stress responses. Revision received: 22 August 1997 / Accepted: 16 September 1997     

Purification and characterization of an epoxide hydrolase from the peroxisomal fraction of mouse liver

Epoxide hydrolase (EH) activity has been reported to occur in most subcellular fractions of mouse liver. The EHs in the microsomal and cytosolic fractions have been purified and characterized; however, the nature of the EH(s) in the peroxisomal fraction is not known. Therefore an EH, pEH, was purified from the solubilized 12,000g fraction, which contain peroxisomes. Previous studies have demonstrated that the EH activity in this crude solubilized 12,000g fraction resides mostly in the peroxisomes. Thus the crude 12,000g pellet from mouse liver, free from cytosolic contamination, was sonicated to obtain a 105,000g soluble fraction containing 80% of the original EH activity in this fraction. The pEH was purified, using trans-stilbene oxide (TSO) as substrate, by a combination of affinity and hydroxyapatite chromatography. The purified pEH had a native molecular weight of 57 kDa, a molecular weight of 59 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and a pI of 5.7. The purified pEH was observed to be immunologically similar to the cytosolic EH (cEH). The kinetics of hydrolysis of TSO, however, were slightly different. Lineweaver-Burk plots for the inhibition of pEH suggest a probable noncompetitive, mixed-type inhibition. The purified pEH thus appears to be very similar to the cEH. There are minor differences between the purified cEH and pEH, particularly in the kinetic parameters. However, these minor differences are insignificant. These results demonstrate that the cEH and pEH are substantially similar, if not identical.     

Superoxide dismutase, peroxidase, and germin-like protein activity in plasma membranes and apoplast of maize roots

Summary. The analysis of plasma membranes from maize roots by native gel electrophoresis revealed the existence of Mn-containing 120 kDa and CuZn-containing 70, 40, and 15 kDa superoxide dismutase (SOD) isoform activities. Isoelectric focusing of the plasma membranes differentiated anionic SOD isoforms with a pI of about 5 and cationic SOD isoforms at pI 8.6. Solubilization of the plasma membrane proteins further separated the cationic SOD into pI 8.6, 8.2, 8.4, and 7.2 isoforms. Double staining for both SOD and peroxidase activities showed an overlap of these activities only in the case of the high-molecular-mass (ca. 120 kDa) isoforms. High-temperature treatments demonstrated that the 120 kDa isoform was active even at 100 °C, indicating that it was a germin-like protein with superoxide-dismutating activity, different from the peroxidase with a similar molecular mass and the lower-molecular-mass CuZn-containing superoxide dismutases. These results are compared to those obtained from whole-tissue extract and apoplastic fluid. Correspondence and reprints: Maize Research Institute, POB 89-Zemun, 11081 Belgrade, Serbia and Montenegro.     

Compared chemical properties of dermonecrotic and lethal toxins from spiders of the genusLoxosceles (Araneae)

Loxosceles spider venom usually causes a typical dermonecrotic lesion in bitten patients, but it may also cause systemic effects that may be lethal. Gel filtration on Sephadex G-100 ofLoxosceles gaucho, L. laeta, orL. intermedia spider venoms resulted in three fractions (A, containing higher molecular mass components, B containing intermediate molecular mass components, and C with lower molecular mass components). The dermonecrotic and lethal activities were detected exclusively in fraction A of all three species. Analysis by SDS-PAGE showed that the major protein contained in fraction A has molecular weight approximately 35 kDa inL. gaucho andL. intermedia, but 32 kDa inL. laeta venom. These toxins were isolated from venoms ofL. gaucho, L. laeta, andL. intermedia by SDS-PAGE followed by blotting to PVDF membrane and sequencing. A database search showed a high level of identity between each toxin and a fragment of theL. reclusa (North American spider) toxin. A multiple sequence alignment of theLoxosceles toxins showed many common identical residues in their N-terminal sequences. Identities ranged from 50.0% (L. gaucho andL. reclusa) to 61.1% (L. intermedia andL. reclusa). The purified toxins were also submitted to capillary electrophoresis peptide mapping afterin situ partial hydrolysis of the blotted samples. The results obtained suggest thatL. intermedia protein is more similar toL. laeta toxin thanL. gaucho toxin and revealed a smaller homology betweenL. intermedia andL gaucho. Altogether these findings suggest that the toxins responsible for most important activities of venoms ofLoxosceles species have a molecular mass of 32–35 kDa and are probably homologous proteins.     

Purification of a thermostable antinociceptive lectin isolated from Andira anthelmia

Andira anthelmia (tribe Dalbergieae), a plant from Brazilian Amazon, possesses a seed lectin that was purified by affinity chromatography in sepharose–mannose. This novel Dalbergieae lectin, named AAL, agglutinated rabbit erythrocytes treated with trypsin. The hemagglutinating activity of AAL was maintained after incubation at a wide range of temperature (40 to 70 °C) and pH, was shown to be dependent on divalent cations, and was inhibited by d ‐mannose and d ‐sucrose. AAL showed an electrophoretic profile in sodium dodecyl sulfate–polyacrylamide gel electrophoresis similar to other lectins of the tribe Dalbergieae, presenting a double band of molecular weight with approximately 20 kDa and other minor bands of 17, 15, and 13 kDa, being the smaller fragment glycosylated. AAL injected by intravenous route in mice showed antinociceptive activity in two behavioral tests (writhing and formalin). In the writhing test induced by acetic acid, AAL showed inhibitory effect at 0.01 mg/kg (68%), 0.1 mg/kg (46%) and 1 mg/kg (74%). In the formalin test, AAL (0.1 mg/kg) inhibited by 48% the licking time in the inflammatory phase, an effect that was recovered by the lectin association with mannose. In conclusion, AAL presents analgesic effect involving the lectin domain via peripheral mechanisms of inflammatory nociception. This activity highlights the importance of lectins as tools to be used for understanding the interaction of protein–carbohydrate in processes associated to inflammatory pain. Copyright © 2015 John Wiley & Sons, Ltd.     

Molecular cloning and characterization of flavonol synthase in Acacia confusa

Flavonoids are abundant in the leaves, flowers, branches, bark, and heartwood of Acacia confusa Merr. (Leguminosae), and the extracts have been found to have strong antioxidant activities. Flavonols are the major class of flavonoids found in A. confusa. The full-length gene (designated as AcFLS) contains an open reading frame of 996 nucleotides encoding 331 amino acid residues with a predicted molecular weight of 38 kDa and pI of 5.7. AcFLS mRNAs were abundant in the seedlings leaves and the flowers. Wounding by cutting leaves induced maximum AcFLS mRNA accumulation 6-12 h after treatment. AcFLS could enzymatically transform dihydromyricetin, dihydroquercetin, and naringenin into the flavonols myricetin, quercetin, and kaempferol, respectively. AcFLS could bind these three substrates with similar affinity.     

Activity of Free and Clay-Bound Insecticidal Proteins from Bacillus thuringiensis subsp. israelensis against the Mosquito Culex pipiens

Bacillus thuringiensis subsp. israelensis produces parasporal insecticidal crystal proteins (ICPs) that have larvicidal activity against some members of the order Diptera, such as blackflies and mosquitoes. Hydrolysis of the ICPs in the larval gut results in four major proteins with a molecular mass of 27, 65, 128, and 135 kDa. Toxicity is caused by synergistic interaction between the 25-kDa protein (proteolytic product of the 27-kDa protein) and one or more of the higher-molecular-mass proteins. Equilibrium adsorption of the proteins on the clay minerals montmorillonite and kaolinite, which are homoionic to various cations, was rapid (<30 min for maximal adsorption), increased with protein concentration and then reached a plateau (68 to 96% of the proteins was adsorbed), was significantly lower on kaolinite than on montmorillonite, and was not significantly affected by the valence of the cation to which the clays were homoionic. Binding of the toxins decreased as the pH was increased from 6 to 11, and there was 35 to 66% more binding in phosphate buffer at pH 6 than in distilled water at pH 6 or 7.2. Only 2 to 12% of the adsorbed proteins was desorbed by two washes with water; additional washings desorbed no more toxins, indicating that they were tightly bound. Formation of clay-toxin complexes did not alter the structure of the proteins, as indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the equilibrium supernatants and desorption washes and by dot blot enzyme-linked immunosorbent assay of the complexes, which was confirmed by enhanced chemiluminescence Western blot analysis. Free and clay-bound toxins resulted in 85 to 100% mortality of the mosquito Culex pipiens. Persistence of the bound toxins in nonsterile water after 45 days was significantly greater (mortality of 63% ± 12.7%) than that of the free toxins (mortality of 25% ± 12.5%).     

A Pyruvated Mannose-Specific Xanthan Lyase Involved in Xanthan Degradation by Paenibacillus alginolyticus XL-1

The xanthan-degrading bacterium Paenibacillus alginolyticus XL-1, isolated from soil, degrades approximately 28% of the xanthan molecule and appears to leave the backbone intact. Several xanthan-degrading enzymes were excreted during growth on xanthan, including xanthan lyase. Xanthan lyase production was induced by xanthan and inhibited by glucose and low-molecular-weight enzymatic degradation products from xanthan. A xanthan lyase with a molecular mass of 85 kDa and a pI of 7.9 was purified and characterized. The enzyme is specific for pyruvated mannosyl side chain residues and optimally active at pH 6.0 and 55°C.