Characterization and Inhibitor Studies of Chitinases from a Parasitic Blowfly (Lucilia cuprina), a Tick (Boophilus microplus), an Intestinal Nematode (Haemonchus contortus) and a Bean (Phaseolus vulgaris)

The molecular weight pattern and the stage-specific activities of chitinases from the blowfly Lucilia cuprina, the tick Boophilus microplus and the intestinal nematode Haemonchus contortus were examined. Chitinolytic enzymes could be detected in all parasite species tested, but the activity was different between the stages. Highest chitinolytic titers were found in blowfly pupae (83 kDa, 118 kDa), hatching larvae of ticks (58 kDa, 94 kDa) and nematode eggs (43 kDa). Leaves from ethylene-treated bean plants Phaseolus vulgaris expressed two basic Class I chitinases (Ia, Ib) of 34 kDa, differing in their amino acid sequences at residue 33 and 34 (Ia: glycine, proline; Ib: lysine, aspartic acid). Inhibitor studies with blowfly pupae revealed that allosamidin (IC₅₀=0·32 (±0·02) μM ) was by far the best inhibitor when compared with various amino sugar derivatives. This compound also inhibited chitinases from tick larvae (IC₅₀=0·69(±0·10) μM ) and nematode eggs (IC₅₀=0·048(±0·0045) μM ) specifically. Whereas Class Ia chitinase from bean leaves was inhibited only up to 18% by 10 μM allosamidin, it had an IC₅₀ of 1(±0·14) μM for the Ib type, which is the first plant chitinase described to be highly sensitive to allosamidin.     

Synthesis and Biological Activity of Allosamidin and Allosamidin Analogues

The chitinase inhibitor/insect ecdysis inhibitor allosamidin and eight allosamidin analogues have been synthesised from simple carbohydrate starting materials. Allosamidin was assayed against Tineola bisselliella (Hummel) larvae and all nine compounds were examined for their effects on the development of larvae of Lucilia cuprina (Wiedemann). High larval mortality compared to controls resulted when T. bisselliella and L. cuprina larva were exposed to allosami-din. The (1→3) linked regioisomer, the dimeric analogue and the gluco-configurated dimeric analogue of allosamidin all showed high activity against L. cuprina larvae. The regioisomer, the (1→3) linked isomer and its dimeric analogue, as well as the monomer allosamizoline and its regioisomer, were inactive. These new in-vivo results are consistent with known in-vitro insect chitinase inhibition data, in that greatest larval mortality was exhibited by the best inhibitors. © 1997 SCI     

Inhibition of two family 18 chitinases by various allosamidin derivatives

The inhibitory activities of several allosamidin derivatives on two family 18 chitinases, an insect enzyme from the epithelial cell line from Chironomus tentans, and a bacterial enzyme, chitinase A from Serratia marcescens, were evaluated. The following structural requirements are necessary for inhibition of the Chironomus enzyme: 1. One N-acetylallosamine residue can be omitted without impairment of enzyme inhibition. 2. At least one N-acetylallosamine sugar must be present. 3. Glucosamine can replace the allosamine moiety without a negative effect on the inhibitory activity. 4. The spatial arrangement of the allosamizoline moiety is important for inhibition. 5. If one sugar is omitted and the arrangement of the cyclitol residue is changed, the inhibitory effect is diminished further. For purified chitinase A from Serratia marcescens the arrangement of the aglycone moiety is equally important, but recognition of the sugar is different: 1. Omission of one allosamine residue decreases the inhibitory activity considerably. 2. Inhibition is improved if the remaining N-acetylallosamine is replaced by the epimer N-acetylglucosamine. Only endochitinase activity is affected, since chitin formation (up to 10^-4 M ) and N-acetylglucosaminidase activity (up to 10^-3 M ) are not impaired, at least in Chironomus cells. © 1998 SCI.     

Differential aphicidal effects of chitinase inhibitors on the polyphagous homopteran Myzus persicae (Sulzer)

Four chitinase inhibitors, cyclo-(Proline-Tyrosine), cyclo-(Histidine-Proline), allosamidin and psammaplin A, were selected for in vitro feeding experiments with the peach-potato aphid, Myzus persicae (Sulzer), under controlled photoperiod and temperature conditions. Artificial diets were used to provide chitinase inhibitors at 10, 50 and 100 microg mL(-1) to M. persicae. Except for cyclo-(Proline-Tyrosine), which did not modify aphid demographic parameters, chitinase inhibitors induced differential aphicidal effects on M. persicae. At all doses, cyclo-(Histidine-Proline) induced significant effects affecting daily fecundity, intrinsic rate of natural increase (r(m)) and doubling time of population. When compared with the control diet, allosamidin decreased nymph survival and daily fecundity, increasing the doubling time of population from 1 to 1.5 days. Psammaplin A was the most toxic inhibitor when delivered via artificial diet, as it induced the death of all aphids reared at 50 and 100 microg mL(-1). The results demonstrate the potential use of chitinase inhibitors as aphid management tools.     

Toxicity and biochemical study of two insect growth regulators, buprofezin and pyriproxyfen, on cotton leafworm Spodoptera littoralis

Lethal and sublethal effects of two insect growth regulators (IGRs) buprofezin and pyriproxyfen were evaluated on larvae of cotton leafworm Spodoptera littoralis. Activity of chitinase and polyphenol oxidase (PPO) in surviving larvae after treatment was carried out in order to investigate the biochemical influences of these compounds. The compounds were low toxic against the larvae at 0.05, 0.1, 0.25, 0.5, and 1.0-fold of the field application rate. However, the overall mortalities within 6 days of feeding at 2.0-fold were 46.67% and 100% for buprofezin and pyriproxyfen, respectively. Larval weight gain was considerably decreased as concentration increased. Pyriproxyfen showed high antifeedant activity in a concentration-dependent manner, and larvae stopped to eat from the third day with high dose. Conversely, buprofezin did not significantly show antifeedant except with high concentration (3000 mg (a.i.)/kg diet) that gave 80.68%. The high doses of both compounds showed adverse effects on pupae, and emergence of adults. Buprofezin at the recommended dose (1500 mg (a.i.)/kg diet) caused 93.33% pupation and 53.33% emergence of adults. Otherwise, pyriproxyfen caused 21.33% pupation and zere emergence of adults at the recommended dose (75 mg (a.i.)/kg diet) compared to 100% pupation, and 96.30% emergence of adults in the control. Both compounds varied in their influences on chitinase and PPO activity, and these enzymes could have relation with toxicity of buprofezin and pyriproxyfen against S. littoralis larvae.     

昆虫生长调节剂和绿僵菌对意大利蝗几丁质酶活力的影响

[目的]探明3种昆虫生长调节剂(苯氧威、氟虫脲、灭幼脲)和一种生物农药(绿僵菌189菌株)对意大利蝗3龄蝗蝻几丁质酶活力的影响.[方法]用药剂处理3龄意大利蝗蝗蝻,用分光光度法测定几丁质酶分解几丁质产物N-乙酰氨基葡萄糖的含量.[结果]3种昆虫生长调节剂浓度达到50mg/L时对几丁质酶的抑制作用超过200％;绿僵菌189菌株对意大利蝗几丁质酶活力也有一定程度的抑制,且抑制作用随着孢子浓度的增加而增大,当孢子浓度达到5×107时,意大利蝗几丁质酶的活力仅为3.8U.[结论]昆虫生长调节剂和绿僵菌均抑制意大利蝗几丁质酶活力.     

几丁质酶抑制剂及噻唑烷酮类化合物合成与农用活性研究进展

几丁质酶(EC 3.2.1.14)可催化几丁质降解生成几丁寡糖,在几丁质代谢通路中发挥着重要作用,在昆虫、真菌和线虫等有害生物的生长发育过程中不可或缺.以几丁质酶为潜在靶标,有望开发出具有全新作用机制的新型农药品种.近年来,由于噻唑烷酮类化合物被报道具有包括几丁质酶抑制活性的多种农用生物活性,其合成方法受到广泛关注.本...     

Biological control of fusarium wilt of cucumber by chitinolytic bacteria

ABSTRACT Two chitinolytic bacterial strains, Paenibacillus sp. 300 and Streptomyces sp. 385, suppressed Fusarium wilt of cucumber (Cucumis sativus) caused by Fusarium oxysporum f. sp. cucumerinum in nonsterile, soilless potting medium. A mixture of the two strains in a ratio of 1:1 or 4:1 gave significantly (P < 0.05) better control of the disease than each of the strains used individually or than mixtures in other ratios. Several formulations were tested, and a zeolite-based, chitosan-amended formulation (ZAC) provided the best protection against the disease. Dose-response studies indicated that the threshold dose of 6 g of formulation per kilogram of potting medium was required for significant (P < 0.001) suppression of the disease. This dose was optimum for maintaining high rhizosphere population densities of chitinolytic bacteria (log 8.1 to log 9.3 CFU/g dry weight of potting medium), which were required for the control of Fusarium wilt. The ZAC formulation was suppressive when added to pathogen-infested medium 15 days before planting cucumber seeds. The formulation also provided good control when stored for 6 months at room temperature or at 4 degrees C. Chitinase and beta-1,3-glucanase enzymes were produced when the strains were grown in the presence of colloidal chitin as the sole carbon source. Partial purification of the chitinases, followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and activity staining, revealed the presence of five bands with molecular masses of 65, 62, 59, 55, and 52 kDa in the case of Paenibacillus sp. 300; and three bands with molecular masses of 52, 38, and 33 kDa in the case of Streptomyces sp. 385. Incubation of cell walls of F. oxysporum f. sp. cucumerinum with partially purified enzyme fractions led to the release of N-acetyl-D-glucosamine (NAGA). NAGA content was considerably greater when pooled enzyme fractions (64 to 67) from Paenibacillus sp. were used, because they contained high beta-1,3-glucanase activity in addition to chitinase activity. Suppression of Fusarium wilt of cucumber by a combination of these two bacteria may involve the action of these hydrolytic enzymes.     

Plant growth promoting rhizobacteria (PGPR) and entomopathogenic fungus bioformulation enhance the expression of defense enzymes and pathogenesis-related proteins in groundnut plants against leafminer insect and collar rot pathogen

The bioformulation of Pseudomonas fluorescens (Pf1 and TDK1) and Beauveria bassiana (B2) strains was evaluated individually and in combinations with and without chitin for their efficacy against leafminer insect and collar rot disease and the effect of the interaction between Pseudomonas, Beauveria and groundnut leafminer insect and collar rot pathogen in the expression of defense enzymes and pathogenesis-related proteins (PR-proteins) in groundnut. Among the various bioformulations, B2 + TDK1 + Pf1 (amended with or without chitin) formulation significantly reduced the incidence of leafminer and collar rot disease when compared to untreated control. A significant increase in the enzymatic activity of phenylalanine ammonia-lyase, peroxidase, polyphenol oxidase, chitinase, β-1,3-glucanase, superoxide dismutase, catalase, lipoxygenase, and phenolics in groundnut plants treated with B2 + TDK1 + Pf1 bioformulation (amended with or without chitin) and challenge inoculated with Aproaerema modicella and Sclerotium rolfsii. Native gel electrophoresis also revealed the expression of more isoforms of pathogenesis-related proteins and other defense enzymes viz., polyphenol oxidase and superoxide dismutase in plants treated with B2 + TDK1 + Pf1 mixture challenged with A. modicella and S. rolfsii. The present study reveals that sustained and timely induction and accumulation of these defense enzymes and PR-proteins enhance the resistance in groundnut against leafminer insect and collar rot disease.     

Enhancement of Postharvest Disease Resistance in Ya Li Pear (Pyrus bretschneideri) Fruit by Salicylic Acid Sprays on the Trees during Fruit Growth

The Ya Li pear (Pyrus bretschneideri) trees were sprayed three times with 2.5 mM salicylic acid (SA) around 30, 60 and 90 days after full flowering. The fruit were harvested at commercial maturity (about 120 days after full flowering), inoculated with Penicillium expansum, and incubated at 20 °C, 95–100% RH. The results showed that resistance to the pathogen of the mature pear fruit was remarkably enhanced by the SA sprays. Disease incidence in the SA-treated fruit was 58.0% or 26.5%, and lesion diameter on SA-treated fruit was 58.4% or 29.0% lower than that in/on fruit without SA treatment (control) on day 12 or 17 after incubation, respectively. The SA spray applied to the trees around 30 days after full flowering notably enhanced accumulation of hydrogen peroxide in the young fruit. Meanwhile, activities of defense enzymes, including peroxidase, phenylalanine ammonia-lyase (PAL), chitinase or β-1,3-glucanase in the young fruit from SA-treated trees was 29.5%, 60.0%, 24.4% or 35.7% higher than that in the control fruit 4 days after the SA spraying. Furthermore, after harvest, activities of PAL, chitinase and β-1,3-glucanase were still significantly higher in the mature pear fruit from the trees sprayed three times with SA than those of the control fruit. Activities of the antioxidant enzymes including catalase and ascorbate peroxidase in the young fruit were significantly reduced by SA spraying. However, the activity of another antioxidant enzyme, glutathione reductase in the young fruit was significantly enhanced by SA spraying. These results suggest that enzymes exerting their functions in different ways may be coordinately regulated by SA in the pear fruit. Our study indicates that treatment of SA sprays on the trees may provide further protection against postharvest disease of Ya Li pear fruit in practice and could be used as an alternative and economical approach to reduce application of chemical fungicides.     

Dietary TH 6040 alters composition and enzyme activity of housefly larval cuticle

Housefly larvae of 2 days of age were allowed to grow in media containing 0, 0.4, 1.0, or 2.5 ppm TH 6040[1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)-urea] for 3 days prior to analysis of the cuticle for structural components (chitin and protein) or enzymes important in cuticle formation (chitinase and phenoloxidase). As the TH 6040 concentration is increased, the amount of chitin is progressively reduced such that, at 2.5 ppm TH 6040, the level is only 25% of normal. The amount of cuticle protein is unaffected so the protein: chitin ratio increases from 3.4 in the control larvae to 14.3 in 2.5 ppm-treated larvae, an alteration which probably affects the elasticity and firmness of the endocuticle. Dietary TH 6040 at 1.0 ppm increases the cuticle chitinase activity to about 180% and the cuticle phenoloxidase activity to 155% as compared with control larvae, with a further chitinase activity increase to 240% of normal at 2.5 ppm TH 6040. These enzyme changes are expected to hamper the build-up or maintenance of the cuticle chitin and enhance sclerotization of the exocuticle.     

Electrophoretic and serological comparisons of pathogenesis-related (b) proteins from different plant species

Preparations of pathogenesis-related (b) proteins (PRs) from differentNicotiana species, tomato,Gynura aurantiaca, bean, and cowpea were compared to each other and to bean chitinase and a constitutive apple agglutinin by electrophoresis in polyacrylamide gels both in the absence and in the presence of SDS, and by serological double diffusion analysis using antisera against tobacco PRs and bean chitinase. PRs from different plant genera displayed a similar but not identical range of relative mobilities in both native and SDS gels, whereas bean chitinase and apple agglutinin were clearly different. None of the antisera reacted with any of the PR preparations from plant genera other than the one from which the antigen(s) had been derived. Whilst PRs within the genusNicotiana are serologically related and can be identical, PRs from different plant genera seem to be sufficiently different to be considered as genus-specific.     

PGPR and entomopathogenic fungus bioformulation for the synchronous management of leaffolder pest and sheath blight disease of rice

BACKGROUND: The biological control of plant pests and diseases using a single organism has been reported to give inconsistent and poor performance. To improve the efficacy, bioformulations were developed possessing mixtures of bioagents. RESULTS: Bioformulations combining Pseudomonas fluorescens Migula strains Pf1 and AH1 and Beauveria bassiana (Balsamo) Vuill. isolate B2 were developed and tested for their efficacy against leaffolder pest and sheath blight disease on rice under glasshouse and field conditions. The combination of Pf1, AH1 and B2 effectively reduced the incidence of leaffolder insect and sheath blight disease on rice compared with other treatments. An in vitro assay of leaffolder preference to rice leaf tissues treated with Pf1 + AH1 + B2 biformulation showed variation from normal growth and development of leaffolder larvae. Plants treated with the Pf1 + AH1 + B2 combination showed a greater accumulation of enzymes, lipoxygenase and chitinase activity against leaffolder insect compared with other treatments. Similarly, the plants showed a higher accumulation of defence enzymes, peroxidase and polyphenol oxidase activity against sheath blight pathogen in Pf1 + AH1 + B2 treatment compared with the untreated control. The bioformulation mixture attracted the natural enemy population of leaffolder under field conditions. In addition, a significant increase in rice grain yield was observed in Pf1 + AH1 + B2 treatment compared with the untreated control. CONCLUSION: The combination of P. fluorescens strains and B. bassiana isolate effectively reduced the incidence of leaffolder insect and sheath blight disease on rice plants and showed the possibility of controlling both pest and disease using a single bioformulation. Copyright © 2010 Society of Chemical Industry     

Combined application of chitinolytic bacterium Paenibacillus sp. D1 with low doses of chemical pesticides for better control of Helicoverpa armigera

Helicoverpa armigera is a serious pest of Cajanus cajan in many parts of world. Rapid development of resistance against number of insecticides and cry toxin-based biocontrol agents has led to search for biocontrol agents with alternative mode of action. The ability of chitinolytic bacteria to degrade vital chitinous structure in insects suggests their potential in insect control. The present investigation was carried out to study insect control potential of a high chitinase producing bacterium, Paenibacillus sp. D1. Biocontrol studies with Helicoverpa larvae showed Paenibacillus sp. D1 and its chitinase to be potent antifeedant that reduced the feeding rate and body weight of the larvae. The decreased body weight was attributed to hydrolysis of the chitinous structures of the larvae. This was evident from decrease in the total chitin content and increased mortality of the larvae fed on the leaves treated with Paenibacillus sp. D1 and chitinase as compared to untreated controls. A combined dose of Paenibacillus sp. D1 or its chitinase with an organophosphate insecticide, acephate, was found to be more lethal than their individual treatments suggesting integrated insect control potential of the bacterium.     

Biological control of Sclerotinia minor using a chitinolytic bacterium and actinomycetes

Isolates of 85 bacteria and 94 streptomycete and 35 nonstreptomycete actinomycetes were obtained from a lettuce-growing field in Al-Ain, United Arab Emirates, on colloidal chitin agar, and screened for their ability to produce chitinase. Twenty-three bacteria and 38 streptomycete and 15 nonstreptomycete actinomycete isolates produced high levels of chitinase and were examined in vitro for their ability to suppress the growth of Sclerotinia minor , a pathogen causing basal drop disease of lettuce. The three most suppressive isolates were examined further for their production of β-1,3-glucanase and antifungal activity as well as their ability to colonize the roots and rhizosphere of lettuce in vitro and in planta . The three isolates, Serratia marcescens, Streptomyces viridodiasticus and Micromonospora carbonacea , significantly reduced the growth of S. minor in vitro , and produced high levels of chitinase and β-1,3-glucanase. Streptomyces viridodiasticus also produced antifungal metabolite(s) that significantly reduced the growth of the pathogen in vitro . When the pathogen was presented as the sole carbon source, all three isolates caused extensive hyphal plasmolysis and cell wall lysis. Serratia marcescens and St. viridodiasticus were competent to varying degrees in colonizing the roots of lettuce seedlings after 8 days on agar plates and the rhizosphere within 14 days in pots, with their competency being superior to that of M. carbonacea . All three isolates, individually or in combination, were antagonistic to S. minor and significantly reduced incidence of disease under controlled glasshouse conditions.     

Molecular cloning of two chitinase genes from Serratia marcescens and their expression in Pseudomonas species

Two chitinase encoding EcoRI fragments from the enteric soil bacterium Serratia marcescens were cloned. From a genomic library of 5686 transductants, 21 expressed chitinase activity as indicated by clearing of a chitin-containing medium. The chitinase encoding clones could be divided into two groups. Four had an 18kb EcoRI fragment and 17 had a 9·4 kb EcoRI fragment. In Southern hybridization experiments the 18kb fragment showed no homology to the 9·4 kb fragment and restriction enzyme maps indicated no similarity. Triparental mating with fluorescent Pseudomonas spp. yielded transconjugants that expressed chitinase activity, inhibited growth of Fusarium oxysporum f. sp. redolens germ tubes and reduced disease of radish caused by the same fungus.     

Temporal synergism can enhance carbamate and neonicotinoid insecticidal activity against resistant crop pests

BACKGROUND: Piperonyl butoxide (PBO) effectively synergises synthetic pyrethroids, rendering even very resistant insect pests susceptible, provided a temporal element is included between exposure to synergist and insecticide. This concept is now applied to carbamates and neonicotinoids. RESULTS: A microencapsulated formulation of PBO and pirimicarb reduced the resistance factor in a clone of Myzus persicae (Sulzer) from >19 000- to 100-fold and in Aphis gossypii (Glover) from >48 000- to 30-fold. Similar results were obtained for a strain of Bemisia tabaci Gennadius resistant to imidacloprid and acetamiprid, although a second resistant strain did not exhibit such a dramatic reduction, presumably owing to the presence of target-site insensitivity and the absence of metabolic resistance. Synergism was also observed in laboratory susceptible insects, suggesting that, even when detoxification is not enhanced, there is degradation of insecticides by the background enzymes. Use of an analogue of PBO, which inhibits esterases but has reduced potency against microsomal oxidases, suggests that acetamiprid resistance in whiteflies is largely oxidase based. CONCLUSION: Temporal synergism can effectively enhance the activity of carbamates and neonicotinoids against resistant insect pests. Although the extent of this enhancement is dependent upon the resistance mechanisms present, inhibition of background enzymes can confer increased sensitivity against target-site resistance as well as increased metabolism. .     

Reaction of resistant and susceptible rice genotypes against brown planthopper (<Emphasis Type="Italic">Nilaparvata lugens</Emphasis>)

The study was carried out to assess the reaction of different rice genotypes in response to brown planthopper (BPH)Nilaparvata lugens (Stål.) attack and the possible use of these genotypes in BPH management. The resistant genotypes PTB 33, ADT 45 and ASD 7 and the moderately resistant genotypes CO 43 and KAU 1661 recorded the lowest nymphal preference, fecundity, feeding rate, survival, growth index, population buildup and plant dry weight loss per mg of insect dry weight produced, and more unhatched eggs, longer nymphal development period, days to wilt and higher Functional Plant Loss Index compared with the susceptible genotype TN1. In resistant and moderately resistant genotypes, a greater accumulation of defense enzymes such as peroxidase and polyphenol oxidase in response toN. lugens infestation was recorded one day after infestation, and more pathogenesis-related protein and chitinase activity was noted 3 days after infestation. The activity was sustained for more than a week after infestation compared with the susceptible genotype TN1.     

The stability and biochemical basis of fufenozide resistance in a laboratory-selected strain of Plutella xylostella

Fufenozide, a novel non-steroidal ecdysone agonist, exhibits good efficacy and plays an important role in controlling lepidopteran pests in China. A high level of resistance to fufenozide (320.3-fold) in Plutella xylostella (L.) has been selected under laboratory conditions. In this study, the stability and biochemical basis of resistance to fufenozide were investigated. The resistance ratio to fufezonide declined substantially from 320.3- to 20.5-fold in the fufenozide resistant strain (JSR) when the selection pressure was removed for six consecutive generations. However, the susceptibility to fufezonide could not be fully restored after 28 generations without exposure to the compound. Increased relative fitness (0.87) was associated with the rapid reversal of resistance in the resistance decaying strain (JSRD). The enzymatic analyses showed reduced specific activities of monooxygenase (MO), glutathione S-transferases (GSTs), carboxylesterase and aryl-acylamidase in the JSRD strain, whereas the activity of chitinase increased. The current findings suggest the selected resistance to fufenozide in P. xylostella is not stable, and the four detoxifying enzymes including MO, GSTs, carboxylesterase, and aryl-acylamidase may be involved. For resistance management proposes, insecticide rotation should be a viable option to delay the occurrence of fufenozide resistance in the field.     

Characteristics of malic enzyme from the cysticerci of Taenia crassiceps (Zeder, 1800)

Kinetic parameters of partly purified malic enzymes (NADP+: L-malate oxidoreductase (decarboxylating) EC 1.1.1.40) from the cytoplasm and mitochondria of Taenia crassiceps cysticerci were compared. The cytoplasmic malic enzyme differed from the mitochondrial malic enzyme in the K'M for malate; other studied properties were identical. The chromatographies of both the cytoplasmic and mitochondrial enzymes were identical. They exhibited a hyperbolic dependence of the activity on malate concentration, sigmoidal kinetics was not observed. The effects of succinate and fumarate known as positive modulators of the activity of malic enzymes from other sources were not observed either in cytoplasmic or mitochondrial enzymes from T. crassiceps. It was found that the two enzymes can be partly inhibited by ATP. Molecular weight of the malic enzyme from T. crassiceps cysticerci was determined by chromatography on Sephadex G-200 (Mw = 116,700) and a four-step purification of the enzyme was performed. The properties of malic enzymes from the cytoplasm and mitochondria of T. crassiceps are compared with those of the malic enzymes from other parasitic worms and higher organisms.