Radiation Chemistry of Foods

An intermediate radical, ?H₂OH, was produced in aqueous methanol solution containing nitrous oxide by γ-irradiation. Yields of ethylene glycol and formaldehyde, the major and the minor product from ?H₂OH, respectively, changed on the addition of some solutes. Cysteine lowered the both product yields to zero even at a low concentration of 5 × 10^?5m. Oxygen of low concentrations (2.5~7.5 × 10^?5 m) changed effectively the major product from ethylene glycol to formaldehyde. k _(CySH+?H2OH)/k_(O2+?H2OH) was calculated as 0.5.

Ascorbic acid (5 × 10^?5 m) lowered ethylene glycol yield to 48%, cystine (10^?3m) to 15%, methionine (10^?3m) to 31%, histidine (10^?3m) to 42%, tryptophan (10^?3m) 46%, tyrosine (10^?3m) to 77%, phenylalanine (10^?3m) to 73%, hypoxanthine (10^?3m) to 37%, adenine (10^?3m) to 52%, uracil (10^?3m) to 20%, thymine (10^?3m) to 10%, cytosine (10^?3 m) to 49%, rutin (10^?3m) to 23%, pyrogallol (10^?3m) to 41%, and gallic acid (10^?3m) to 78% of the control. These results suggest that the reactions of the secondary radicals such as ?H₂OH perform an important role in material change of foods irradiated with γ rays.     

Kinetic Studies on Crystalline Yeast Phosphoglyceric Acid Mutase

Effects of the substrate and the coenzyme on the crystalline yeast phosphoglyceric acid mutase activity have been investigated. Lineweaver-Burk plots at different concentrations of the substrate (d-3-phosphoglyceric acid: 3×10^?7 to 8×10^?3m) and the coenzyme (d-2, 3-diphosphoglyceric acid: 8×10^?7 to 10^?5m) change in such a way to indicate the involvement of an enzyme-substrate-coenzyme ternary complex as an active intermediate in the enzymic reaction process. It is concluded that the reaction catalyzed by the yeast enzyme follows the sequential pathway and that a phosphorylated enzyme does not participate as an obligatory intermediate in the reaction mechanism, if it occurs. Kinetic studies indicate Km values of 6×10^?4m for d-3-phosphoglyceric acid and 8×10^?7m for d-2, 3-diphosphoglyceric acid. The substrate is a competitive inhibitor of the coenzyme with a Ksi (inhibition constant) of 3.2×10^?3m. The coenzyme inhibition is not observed at concentration tested. A kinetic treatment to determine the mechanism of the enzyme reaction from the experimental data which are obtaind in the range of inhibitory substrate concentrations is presented.     

Studies on d-Glucose-isomerizing Activity of d-Xylose-grown Cells from Bacillus coagulans,Strain HN-68

d-Glucose-isomerizing enzyme has been extracted in high yield from d-xylose-grown cells of Bacillus coagulans, strain HN-68, by treating with lysozyme, and purified approximately 60-fold by manganese sulfate treatment, fractionation with ammonium sulfate and chromatography on DEAE-Sephadex column. The purified d-glucose-isomerizing enzyme was homogeneous in polyacrylamide gel electrophoresis and ultracentrifugation and was free from d-glucose-6-phosphate isomerase. Optimum pH and temperature for activity were found to be pH 7.0 and 75°C, respectively. The enzyme required specifically Co⁺⁺ with suitable concentration for maximal activity being 10^?3 m. In the presence of Co⁺⁺, enzyme activity was inhibited strongly by Cu⁺⁺, Zn⁺⁺, Ni⁺⁺, Mn⁺⁺ or Ca⁺⁺. At reaction equilibrium, the ratio of d-fructose to d-glucose was approximately 1.0. The enzyme catalyzed the isomerization of d-glucose, d-xylose and d-ribose. Apparent Michaelis constants for d-glucose and d-xylose were 9×10^?2 m and 7.7×10^?2 m, respectively.     

Bacterial Racemization of α-Amino-ε-caprolactam

1. Several bacteria were isolated from soil which grew on both d- and l-aminolactam and whose cells had an activity to racemize them. They were identified as Achromobacter obae nov. sp., Achr. cycloclastes, Alcaligenes faecalis and Flavobacterium arborescens.

2. Racemization of d- and l-aminolactam was investigated using the lyophilized cells of Achr. obae nov. sp. The optimum pH value of the reaction was about 8.0. The racemizing activity was completely inhibited by 10^?4 m hydroxylamine, and the inhibition was removed by 10^?4 m pyridoxal phosphate. Five percent d- and l-aminolactam solutions were completely racemized with a concomitant slight formation of l-lysine.     

Properties of Tyrosinase from Pseudomonas melanogenum

The properties of the tyrosinase from Pseudomonas melanogenum was investigated with the crude enzyme preparation. Optimum temperature and pH of the enzyme were 23°C and 6.8, respectively. l-Tyrosine, d-tyrosine, m-tyrosine, N-acetyl-l-tyrosine and l-DOPA were utilized as a substrate by the enzyme. The value for Km obtained were as follows: l-tyrosine 6.90 × 10^?4 m, d-tyrosine 1.43 ×10^?3 m and l-DOPA 9.90 × 10^?4 m. The enzyme was inhibited by chelating agents of Cu²⁺ l-cysteine, l-homocysteine, thiourea and diethyl-dithiocarbamate and the inhibition was completely reversed by the addition of excess Cu²⁺ From these results it is concluded that the enzyme is a copper-containing oxidase.     

Crystalline d-Mannitol:NAD Oxidoreductase from Leuconostoc mesenteroides

The crystalline d-mannitol dehyrogenase (d-mannitol:NAD oxidoreductase, EC 1.1.1.67) catalyzed the reversible reduction of d-fructose to d-mannitol. d-Sorbitol was oxidized only at the rate of 4% of the activity for d-mannitol. The enzyme was inactive for all of four pentitols and their corresponding 2-ketopentoses. The apparent optimal pH for the reduction of d-fructose or the oxidation of d-mannitol was 5.35 or 8.6, respectively. The Michaelis constants were 0.035 m for d-fructose and 0.020 m for d-mannitol. The enzyme was also found to be specific for NAD. The Michaelis constans were 1 × 10^?5 m for NADH₂ and 2.7 × 10^?4 m for NAD.     

Regulatory Properties of Prephenate Dehydrogenase and Prephenate Dehydratase from Corynebacterium glutamicum

Regulatory properties of the enzymes in l-tyrosine and l-phenyalanine terminal pathway in Corynebacterium glutamicum were investigated. Prephenate dehydrogenase was partially feedback inhibited by l-tyrosine. Prephenate dehydratase was strongly inhibited by l-phenylalanine and l-tryptophan and 100% inhibition was attained at the concentrations of 5 × 10^?2mm and 10^?1mm, respectively. l-Tyrosine stimulated prephenate dehydratase activity (6-fold stimulation at 1 mm) and restored the enzyme activity inhibited by l-phenylalanine or l-tryptophan. These regulations seem to give the balanced synthesis of l-tyrosine and l-phenyl-alanine. Prephenate dehydratase from C. glutamicum was stimulated by l-methionine and l-leucine similarly to the enzyme in Bacillus subtilis and moreover by l-isoleucine and l-histidine. C. glutamicum mutant No. 66, an l-phenylalanine producer resistant to p-fluorophenyl-alanine, had a prephenate dehydratase completely resistant to the inhibition by l-phenylalanine and l-tryptophan.     

Amino Acid Metabolism in Microorganisms

3-Methylthiopropylamine (MTPA) formation from l-methionine in Streptomyces sp. K37 was studied in detail. The reaction was confirmed to be catalyzed by the decarboxylase of l-methionine. The properties of the enzyme were studied in detail using acetone dried cells or cell-free extract. The enzyme was specific for l-methionine. Pyridoxal phosphate stimulated the reaction and protected the enzyme against heat inactivation. The optimum pH for the reaction was 6.0~8.0 and the optimum temperature was about 40°C. Carbonyl reagents (10^?2~10^?3 m) inhibited the reaction completely, and silver nitrate and mercuric chloride (10^?3~10^?4 m) markedly inhibited the reaction. Km value for the reaction was 1.21 × 10^?5 m. l-Methionine assay using the decarboxylase was attempted and was found to be applicable to practical use.     

Purification and Crystallization of d-Arabinose (l-Fucose) Isomerase from Aerobacter aerogenes by Polyethylene Glycol

d-Arabinose(l-fucose) isomerase (d-arabinose ketol-isomerase, EC 5.3.1.3) was purified from the extracts of d-arabinose-grown cells of Aerobacter aerogenes, strain M-7 by the procedure of repeated fractional precipitation with polyethylene glycol 6000 and isolating the crystalline state. The crystalline enzyme was homogeneous in ultracentrifugal analysis and polyacrylamide gel electrophoresis. Sedimentation constant obtained was 15.4s and the molecular weight was estimated as being approximately 2.5 × 10⁵ by gel filtration on Sephadex G-200.

Optimum pH for isomerization of d-arabinose and of l-fucose was identical at pH 9.3, and the Michaelis constants were 51 mm for l-fucose and 160 mm for d-arabinose. Both of these activities decreased at the same rate with thermal inactivation at 45 and 50°C. All four pentitols inhibited two pentose isomerase activities competitively with same Ki values: 1.3–1.5 mm for d-arabitol, 2.2–2.7 mm for ribitol, 2.9–3.2 mm for l-arabitol, and 10–10.5 mm for xylitol. It is confirmed that the single enzyme is responsible for the isomerization of d-arabinose and l-fucose.     

Inhibition of l-Alanine Adding Enzyme by Glycine

l-Alanine adding enzymes from Bacillus subtilis and Bacillus cereus which catalyzed l-alanine incorporation into UDPMurNAc were partially purified and the properties of the enzymes were examined. The enzyme from B. subtilis was markedly stimulated by reducing agents including 2-mercaptoethanol, dithiothreitol, glutathione and cysteine. Mn²⁺ and Mg²⁺ activated l-alanine adding activity and their optimal concentrations were 2 to 5 mm and 10 mm, respectively. The optimum pH was 9.5 and the Km for l-alanine was 1.8×10^?4m. l-Alanine adding reaction was strongly inhibited by p-chloromercuribenzoate and N-ethyl-maleimide. Among glycine, l- and d-amino acids and glycine derivatives, glycine was the most effective inhibitor of the l-alanine adding reaction. The enzyme from B. cereus was more resistant to glycine than that from B. subtilis. Glycine was incorporated into UDPMurNAc in place of l-alanine, and the Ki for glycine was 4.2×l0^?3m with the enzyme from B. subtilis. From these data, the growth inhibition of bacteria by glycine is discussed.     

Studies on the Pentose Isomerases of Lactic Acid Bacteria

Production of d-xylose and l-arabinose isomerases by lactic acid bacteria was greatly promoted by the addition of manganese ions in cultural medium. Effective concentration of the ions was 5 × 1O^-3 m. Ferrous ions were also effective for the production of d-xylose isomerase and cobaltous ions were somewhat effective for the production of l-arabinose isomerase. Zinc and cadmium ions inhibited bacterial growth. It was possible to increase the production of isomerase by changing MnSO₄ concentration to 5× 10^-3 m (0.l1 %) in place of 0.001 per cent in the normal medium.

Column chromatographic procedures for the purification of pentose isomerases were carried out. Cation and anion exchange resins were not suitable because of their low exchange capacities and instability of the enzyme at acidic pH range. But the isomerases were successfully purified by DEAE-cellulose column chromatography with high recovery (85~90%). Using a Tris buffer, KCl concentration was increased in gradient. d-Xylose isomerase was eluted at pH 7.0 at 0~0.2 m KCl, and l-arabinose isomerase at pH 8.0 at 0~0.4 m KCl. The purified isomerases, d-xylose isomerase and l-arabinose isomerase, both required manganese ions specifically for their activities.

D-Xylose isomerase and l-arabinose isomerase are different enzymes which can be separated from each other with acetone fractionation at pH 4.8~5.0, heat treatment or chromatography on a colnmn of DEAE-cellulose. In DEAE-cellulose chromatography with a linear gradient elution method, d-xylose isomerase is recovered in the first peak at pH 7.0 (Tris bnffer) with 0~0.2 m KCl, and l-arabinose isomerase is eluted in the second peak at pH 8.0 (Tris buffer) with a larger ionic strength.     

Optimization of the 503 antigen induction strategy of Leishmania infantum chagasi expressed in Escherichia coli M15

Abstract

Leishmaniosis is a complex of diseases that can be fatal, if not given proper attention. Despite its relevance in the public health system, there is no vaccine capable of preventing the disease in humans so far and its treatment is expensive and aggressive to human health. The present study aims to optimize the induction parameters of the 503 Leishmania i. chagasi antigen expressed in recombinant Escherichia coli M15. The induction at different cell densities was evaluated in order to analyze the influence of the induction time on the yield of the protein of interest. In this segment, lactose and isopropyl-β-d-thiogalactopyranoside (IPTG) were used as inducer molecules, using various concentrations: 0.1?g/L, 1.0?g/L, and 10?g/L for lactose and 20?μM, 100?μM, 500?μM, and 1000?μM for IPTG. The results presented that the concentration of IPTG that obtained the higher antigen levels was that of 100?μM (0.087?g/L), a 10-fold lower concentration than was being previously used in this type of system and for lactose, it was 1?g/L (0.016?g/L). Thus, the induction with 100?μM allowed obtaining the antigen with a concentration 5.6 times higher than the lactose induction maximum concentration.     

Regulatory Properties of Chorismate Mutase from Corynebacterium glutamicum

Regulatory properties of chorismate mutase from Corynebacterium glutamicum were studied using the dialyzed cell-free extract. The enzyme activity was strongly feedback inhibited by l-phenylalanine (90% inhibition at 0.1~1 mm) and almost completely by a pair of l-tyrosine and l-phenylalanine (each at 0.1~1 mm). The enzyme from phenylalanine auxotrophs was scarcely inhibited by l-tyrosine alone but the enzyme from a wild-type strain or a tyrosine auxotroph was weakly inhibited by l-tyrosine alone (40~50% inhibition, l-tyrosine at 1 mm). The enzyme activity was stimulated by l-tryptophan and the inhibition by l-phenylalanine alone or in the simultaneous presence of l-tyrosine was reversed by l-tryptophan. The Km value of the reaction for chorismate was 2.9 } 10^?3 m. Formation of chorismate mutase was repressed by l-phenylalanine. A phenylalanine auxotrophic l-tyrosine producer, C. glutamicum 98–Tx–71, which is resistant to 3-amino-tyrosine, p-aminophenylanaine, p-fluorophenylalanine and tyrosine hydroxamate had chorismate mutase derepressed to two-fold level of the parent KY 10233. The enzyme in C. glutamicum seems to have two physiological roles; one is the control of the metabolic flow to l-phenylalanine and l-tyrosine biosynthesis and the other is the balanced partition of chorismate between l-phenylalanine-l-tyrosine biosynthesis and l-tryptophan biosynthesis.     

Studies on Metabolism of Pyrrolidone Carboxylic Acid in Bacteria

l-Glutamic acid was formed from d-, l-, and dl-PCA with cell-free extract of Pseudomonas alcaligenes ATCC-12815 grown in the medium containing dl-PCA as a sole source of carbon and nitrogen. The enzyme(s) involved in this conversion reaction was distributed in the soluble fraction within the cell and in 0.5 saturated fraction at the fractionation procedure with the saturation of ammonium sulfate. Optimum pH of this enzyme(s) lied at pH 8.5 and optimum temperature was 30°C. Cu (5 × 10^?3 m) inhibited the reaction considerably while Ca or Fe accelerated it. PALP (1×10^?3 m) also gave an enhanced activity to some extent. The enzyme preparation converted dextro-rotatory enan-thiomorph of PCA to its laevo-rotatory one which in turn was not converted to the opposite rotation direction by this enzyme. Furthermore, the preparation did not, if any, show d-glutamic acid racemase activity. Isotopic experiments with using dl-PCA-1-¹⁴C revealed that l-glutamic acid-1-¹⁴C was formed by the cleavage of –CO–NH– bond of pyrrolidone ring of PCA. It was concluded that dl-PCA when assimilated by the present bacterium is at first transformed to l-PCA by the optically isomerizing enzyme and subsequently is cleaved to l-glutamic acid probably by the PCA hydrolysing enzyme.     

Kinetic Studies on Xylanase Induction by β-Xyloside in Streptomyces sp.

Xylanase induction by β-xyloside was investigated in non-growing conditions using non-induced mycelia of Streptomyces sp. No. 3137 harvested from glucose medium. The mycelia started to produce xylanase without lag time when β-xyloside was added. The rate of xylanase synthesis was dependent on the concentration of β-xyloside added to the inducing culture medium. The induction constants of various β-xylosides were calculated from the Lineweaver-Burk plots; those of methyl-, isopropyl-, butyl- and ethylencyanohydrin-β-d-xylosides were 10.53 mm, 3.83 mm, 0.55mm and 0.25 mm, respectively. Some α-xylosides repressed xylanase synthesis. The rate of xylanase synthesis decreased suddenly after the addition of α-xyloside. The inhibition constants of methyl-, ethyl- and isopropyl-α-d-xylosides were 8.80 mm, 12.50 mm and 33.33 mm, respectively. The xylanase induction was also repressed by glucose. However, this repression was completely restored after consuming additional glucose.     

Kinetic Properties of Fungal Polyamine Oxidases and Their Application to Differential Determination of Spermine and Spermidine

Polyamine oxidase from Penicillium chrysogenum oxidized spermine rapidly and spermidine slightly at pH 7.5. The apparent Km values for spermine and spermidine were calculated to be 2.25 × 10^?5 m and 9.54 × 10^?6 m, respectively. The relative maximum velocities for spermine and spermidine were 3.37 × 10^?3 m (H₂O₂) per min per mg of protein and 2.08 × 10^?4 m (H₂O₂) per min per mg of protein, respectively. Spermine oxidation of the enzyme was competitively inhibited by spermidine and putrescine. The apparent Ki values by spermidine and putrescine were calculated to be 3.00 × 10^?5 m and 1.80 × 10^?8 m, respectively. On the other hand, polyamine oxidase from Aspergillus terreus rapidly oxidized both spermidine and spermine at pH 6.5. The apparent Km values for spermidine and spermine were 1.20 × 10^?8 m and 5.37 × 10^?7 m, respectively. The relative maximum velocities for spermidine and spermine were 1.55 × 10^?2 m (H₂O₂) per min per mg of protein and 6.20 × 10^?3 m (H₂O₂) per min per mg of protein, respectively.

Differential determination of spermine and spermidine was carried out using the two enzymes. The initial rate was assayed with Penicillium enzyme and the end point was measured afte addition of Aspergillus enzyme. Small amounts of polyamines (25 to 200 nmol of spermine and 25 to 250 nmol of spermidine) were assayed by solving two simultaneous equations obtained from the rate assay method and the end point assay method. The calculated values were in close agreement with those obtained by an amino-acid analyzer.     

Purification and Properties of l-Arginase from Bacillus subtilis

l-Arginase (l-arginine amidinohydrolase, EC 3.5.3.1) was purified in a crystalline form from cells of Bacillus subtilis KY 3281 with an overall yield of 23.2%. The crystalline enzyme had a specific activity of 858 i.u./mg-protein and was ultracentrifugally homogeneous. It was estimated to have a molecular weight of 115,000±5000 by the method of Yphantis.

The enzyme highly specific for l-arginine showed the maximum activity at pH 10 with Mn²⁺ ion. The Km for l-arginine was 1.35 × 10^?2 m The activity was competitively inhibited by l-lysine, but not by l-ornithine and increased by the addition of Mn²⁺ or Co²⁺ ions. The stable pH and temperature ranges became wider in the presence of Mn²⁺ ion and l-threonine.     

Fukiic Acid Isolated from the Hydrolysate of a Polyphenol in Petasites japonicus

d-Glucose-isomerizing enzyme was purified in a crystalline form with a good yield from the cells of Bacillus coagulans, strain HN-68, and some phsicochemical properties were investigated.

The purified enzyme was homogeneous on both ultracentrifugal and disc-electrophoretical analyses. The molecular weight of the enzyme was determined to be 175,000 and 160,000 from the sedimentation-viscosity method and the gel filtration method, respectively.

The sedimentation coefficient , partial specific volume, at 280 mμ, and the nitrogen content of the enzyme were determined to be 10.2×10^?13 sec, 0.705 cm³g^?1, 10.6 and 16.2%, respectively. The integral numbers of amino acid residues per molecule calculated on the basis of 160,000 were as follows; Lys₁₂₀, His₄₉, Arg₆₁, Asp₁₈₂, Thr₈₇, Ser₇₀, Glu₁₃₆, Pro₄₄, Gly₁₀₆, Ala₁₄₀, Half-Cys₀, Val₅₃, Met₂₇, Ileu₅₁, Leu₁₃₄, Tyr₅₈, Phe₉₆, Try₁₃, and amide-ammonia₈₀.

Purified enzyme preparation obtained from Bacillus coagulans, strain HN-68 requires Co²⁺ for d-glucose- and d-ribose-isomerizing activities and Mn²⁺ for d-xylose-isomerizing activity. The values of Km for d-glucose, d-xylose and d-ribose were 9×10^?2, 1.1×10^?3, 7.7×1O^?m and of the relative V_max were 0.52, 1.1 and 0.25 mg/min at 40°C, respectively. d-Glucose-isomerizing activity was inhibited by d-xylose and d-ribose. However, there was not a difference among three activities of the enzyme with respect to following properties: Activation energy was 14,600 cal per mol. The enzyme was inhibited in a competitive manner by tris(hydroxymethyl)aminomethane, d-xylitol, d-sorbitol and d-mannitol, and the Ki values for these inhibitor were 3×10^?4, 2.5×10^?3, 2.9×10^?2 and 7×10^?2m, respectively. The ratio of three activities did not change by heat- and pH-treatments. Mn²⁺, Co²⁺ and Ni²⁺ protected strongly the enzyme from heat denaturation. The enzyme can isomerize d-glucose, d-xylose and d-ribose to their corresponding ketose, but the kinetic constants and induction studies indicated that ^d-xylose is the natural substrate for the enzyme.     

Simultaneous Measurement of Dissolved Oxygen and Oxidation-Reduction Potentials in the Aerobic Culture

The most dominant factor influencing the oxidation-reduction potentials (E) in the cultured system was oxygen tension. H was an useful index to express the degree of oxygen supply in place of dissolved oxygen (P_L) under a limited oxygen supply. The conversion of microbial products caused by the change in oxygen supply was clearly analyzed by the use of E value. Bacillus subtilis excreted lactic acid at the E value ?220 mV, 2,3-butyleneglycol at ?195 mV and acetoin at ?160mV as the main product. E also gave the significant information concerning the changes in cell’s respiration. Cyanide at the concentration of 10^?5m, azide at 10^?3m and 2,4-dinitrophenol (DNP) at 10^?2m inhibited cell respiration causing the decrease in E and the increase in P_L, and DNP at 0.4×10^?3m promoted oxygen uptake of the cells causing the decrease in both E and P_L.     

Studies on the Mode of Action of Polyoxins

(1) Chitin-UDP acetylglucosaminyltransferase (E.C. 2.4.1.16., chitin synthetase) in the cell-free system from phytopathogenic fungus Piricularia oryzae, and effects of various polyoxins and related compounds on the enzyme activity were studied. Polyoxins A~M, polyoxin A derivatives, polyoxin C derivatives, 5′-amino-5′-deoxyuridine, uridine and thymidine inhibited equally the incorporation of N-acetylglucosamine (GlcNAc) from UDP-N-acetylglucosamine (UDP-GlcNAc) into chitin.

(2) Competition between the above inhibitors and UDP-GlcNAc was observed by kinetic studies. The Km for UDP-GlcNAc was determined to be 3.3 × 10^?3 m and the Ki values for polyoxins A~M, except polyoxin C, were found to be in the range of 3.3 × 10^?5 m to 3.4 × 10^?6 m. For polyoxin C, 5′-amino-5′-deoxyuridine and uridine, the Ki values of 2.7 × 10^?3 m, 8.0 × 10^?3 m and 3.0 × 10^?3 m were given, respectively. The inhibitor constants for other related compounds were also calculated.

(3) The values of binding affinity, ?ΔG, for formation of substrate- or inhibitor-enzyme complexes were calculated from the Km or Ki values. In addition, partial binding affinities, ?Δg, for certain moieties or groups of polyoxins were estimated from the ?ΔG. For instance, the ?ΔG values for UDP-GlcNAc and polyoxin L were 5.7 kcal/mole and 9.2 kcal/mole, respectively. And the ?Δg values for the nucleoside moiety (part I), the carbamylpolyoxamic acid moiety (part II) and the carboxyl group at C5′ position of polyoxin L were 5.2, 3.5 and 0.7 kcal/mole, respectively.

(4) From the results obtained, the mechanism of action and relation between chemical structure and competitive inhibition of chitin synthetase were discussed.