A β-citryl-L-glutamate-hydrolysing enzyme in rat testes

An enzyme responsible for the deacylation of β-citryl-L-glutamate to citrate and glutamate has been characterized in rat testis. The enzyme required manganese ion for full activity and was strongly inhibited by nucleotides such as ATP or GTP. The activity was localized in the particulate fractions. The enzyme favored $\text{N-}\text{formyl-}\text{L}\text{-glutamate}\text{> β-}\text{citryl-}\text{L}\text{-glutamate}\text{> β-}\text{citryl-}\text{L}\text{-glutamine}$ in a decreasing order. The amidohydrolyase activity was highest in the testis and lung, a moderate activity was detected in heart, kidney and intestine, and low in brain, thymus, stomach, skeletal muscle, spleen and liver. These findings suggest that the amidohydrolase is different from any of amidohydrolases reported so far, amidohydrolase I (EC 3.5.1.14), II (EC 3.5.1.15), III, N-acetyl-lysine deacylase (EC 3.5.1.17) and N-acetyl-β-alanine deacetylase (EC 3.5.1.21), and various peptidases.     

The cbiS gene of the archaeon Methanopyrus kandleri AV19 encodes a bifunctional enzyme with adenosylcobinamide amidohydrolase and alpha-ribazole-phosphate phosphatase activities

Here we report the initial biochemical characterization of the bifunctional alpha-ribazole-P (alpha-RP) phosphatase, adenosylcobinamide (AdoCbi) amidohydrolase CbiS enzyme from the hyperthermophilic methanogenic archaeon Methanopyrus kandleri AV19. The cbiS gene encodes a 39-kDa protein with two distinct segments, one of which is homologous to the AdoCbi amidohydrolase (CbiZ, EC 3.5.1.90) enzyme and the other of which is homologous to the recently discovered archaeal alpha-RP phosphatase (CobZ, EC 3.1.3.73) enzyme. CbiS function restored AdoCbi salvaging and alpha-RP phosphatase activity in strains of the bacterium Salmonella enterica where either step was blocked. The two halves of the cbiS genes retained their function in vivo when they were cloned separately. The CbiS enzyme was overproduced in Escherichia coli and was isolated to >95% homogeneity. High-performance liquid chromatography, UV-visible spectroscopy, and mass spectroscopy established alpha-ribazole and cobyric acid as the products of the phosphatase and amidohydrolase reactions, respectively. Reasons why the CbiZ and CobZ enzymes are fused in some archaea are discussed.     

Effect of different compounds on 1-aspartamido-beta-N-acetylglucosamine amidohydrolase from human liver.

The effect of varous compounds on 1-aspartamido-beta-N-acetylglucosamine amidohydrolase (aspartylglucosylaminase, EC 3.5.1.26) was studied. N-Acetylcysteine inhibited the nezyme non-competitively (Ki 3.2 mM), whereas 3-hydroxybutanone inhibited competitively (Ki 4.1 mM). Methionine, isoleucine and cystathionine apparently enhanced the enzyme activity. The enzyme had a mol. wt. of 63000 as determined by gel filtration. The present studies differentiate between the aspartylglucosylaminase from human liver and that obtained from various other sources.     

Cyanase-mediated utilization of cyanate in Pseudomonas fluorescens NCIB 11764.

Pseudomonas fluorescens NCIB 11764 was capable of utilizing cyanate (OCN-) as a sole nitrogen source for growth. Crude cell extracts from cells grown on cyanate, but not on ammonium sulfate, were induced for an enzyme catalyzing cyanate conversion to ammonia. Enzymatic activity was shown to be bicarbonate dependent and specific for cyanate as a substrate, suggesting that cyanate utilization in this organism is facilitated by an enzyme resembling cyanase (cyanate amidohydrolase; EC 3.5.5.3), as described previously in Escherichia coli and Flavobacterium sp.     

四季豆幼苗中尿囊酸酰胺水解酶的一些特性

酰脲代谢在许多固氮豆科植物氮素代谢中起重要作用;尿囊酸的酰胺水解酶(EC3.5.3.9)分解尿囊酸成为脲基乙醇酸和CO2、NH3,脲基乙醇酸的酰胺水解酶进一步分解脲基乙醇酸产生乙醛酸和CO2、NH3.该文首次报告测定四季豆尿囊酸降解酶(分解尿囊酸的酶)的方法,酶反应基质需要盐酸苯肼存在.在四季豆干种子、幼苗根、茎和叶,均可测出尿囊酸降解酶活力.从四季豆幼苗分离出两个尿囊酸降解酶.一个分子量大于200 kD,另一个分子量为13.5 kD;小分子量的尿囊酸降解酶(没有脲基乙醇酸酰胺水解酶或脲酶活力)用于性质研究.酶反应产物分析表明,该酶是尿囊酸的酰胺水解酶.该酶反应的最适pH为8.5.Mn2 是该酶的金属辅助因子.Km为76μmol/L,Vmax为16.7 nKat/mg(=1 002 nmol min1mg1).乙醛酸和乙醇酸抑制该酶活力.赖氨酸残基和色氨酸残基是酶活力的必需基团;巯基和酪氨酸残基不是酶活力的必需基团.     

Measurement of 1-aspartamido-beta-N-acetylglucosamine amidohydrolase activity in human tissues.

The activity of 1-aspartamido-beta-N-acetylglucosamine amidohydrolase (aspartylglucosylaminase, EC 3.5.1.26) was measured in normal and diseased human liver, brain and kidney. Organs from patients with aspartylglucosaminuria show very little activity. Crude homogenates of human organs show a reaction catalysed by a complex enzyme system. With homogenate, the formation of product was linear with time up to about 6 h. Reaction times longer than 6-7h resulted in a decrease in the total concentration of product. This phenomenon was not found with the partially purified enzyme fraction. Linearity of the enzyme activity with different protein concentrations was found, independent of the incubation time. Longer incubation of the crude homogenate resulted in the utilization of the product, N-acetylglucosamine. This phenomenon was not observed with the partially purified enzyme fraction. This amidase from human organs differs from that obtained from other sources and apparently represents a rather complex enzyme system.     

Study of microencapsulated urease in a continuous feed,stirred tank reactor

Urease, (urea amidohydrolase, EC 3.5.1.5) co-encapsulated with haemoglobin in cellulose nitrate membranes was found to exhibit apparent Michaelis-Menten kinetics; however, a steadily increasing apparent Michaelis-Menten constant over the lifetime of the preparation was observed. The activity of the enzyme in a continuous feed stirred tank reactor (CSTR) was investigated and correlated with a mathematical model derived from basic Michaelis-Menten kinetics. Plots relating substrate conversion to feed substrate concentration and tank reactor capacity were constructed and found to be accurate to less than 15% error under the experimental conditions studied.     

The structure and function of acid proteases. VII. Distribution and some properties of acid proteases in monkey tissues.

1. The distribution of acid protease activity in various tissues of Japanese monkey (Macaca fuscata fuscata) was investigated with hemoglobin as a substrate at pH 3.0. The activity per protein weight in crude extracts was highest in spleen and lung, and decreased in the order: spleen, lung greater than kidney, testis greater than brain greater than liver, placenta greater than thyroid gland, muscle. The activity in crude muscle extract was about one-tenth those of spleen and lung. The activity per wet tissue weight was in roughly the same order except for a lower activity per wet weight of brain. 2. Upon chromatography of each crude extract on a Sephadex G-100 column, one major activity peak was eluted at a position corresponding to a molecular weight of about 41,000. This enzyme activity is attributed to cathepsin D [EC 3.4.23.5]. In addition, a minor activity peak was eluted in the case of spleen, lung and kidney at the break-through position, corresponding to a molecular weight of more than 100,000. This activity peak is presumably due to cathepsin E. These acid protease activities were, in most cases, strongly inhibited by pepstatin, an acid protease-specific peptide inhibitor. 3. The distribution of acid protease activity was investigated in the brain of crab-eating monkey (Macaca fascicularis). The activity was fairly evenly distributed among several regions of the brain, and its distribution was similar to those of other acid hydrolases, especially N-acetyl-beta-D-glucosaminidase [EC 3.2.1.30] and acid phosphatase [EC 3.1.3.2], which are marker enzymes of lysosomes.     

Immobilization of urease within a thin channel ultrafiltration cell

Urease [urea amidohydrolase, EC 3.5.1.5] has been immobilized within a thin channel ultrafiltration cell. Loss of enzymic activity as a result of concentration polarization and other causes was minimized. The flow characteristics of the reactor were fully characterized by analysis of the distribution of residence times (using F diagrams) and kinetic data were also obtained for the immobilized enzyme. These data show that under certain conditions the thin channel ultrafiltration reactor can be considered to be an ideally mixed vessel. After almost 8 days of continuous operation it was found that 15% of the original enzyme activity remained.     

On the partial reactivation of inactivated pantothenase from Pseudomonas fluorescens.

Partial reactivation of inactivated pantothenase (pantothenate amidohydrolase, EC 3.5.1.22) from Pseudomonas fluorescens was studied. After partial inactivation during storing, pantothenase activity is increased by 10-40% when incubated with, for instance, oxalate, oxaloacetate or pyruvate. Reactivation proceedes slowly; with oxaloacetate the stable level of enzyme activity is attained in 20-30 min. The same compounds also cause reactivation of thermally inactivated pantothenase when partial inactivation has occurred at 28-37 degrees C. The amount of the reactivating enzyme form is relatively greater the lower the temperature during inactivation, but it never exceeds 20% of the original amount of active enzyme. Also another, unstable form of pantothenase is formed in thermal inactivation. This form becomes inactivated in a few minutes after the heat treatment, at pH 6-8 and at temperatures between 0 and 10 degrees C. Reactivation causes special problems in enzyme kinetic measurements; for instance, curvature is found in the lines of Ki determination by the Dixon plot.     

Studies on immobilized enzymes. IX. Preparation and properties of aminoacylase covalently attached to halogenoacetylcelluloses

Immobilization of mold aminoacylase (N-acylamino acid amidohydrolase, EC 3.5.1.14) was investigated by covalently binding the enzyme to halogenoacetylcelluloses. As a result, the iodoacetylcellulose was found to be the best carrier among the halogenoacetylcelluloses. The yield of activity of the insoluble aminoacylase relative to that of the native aminoacylase used was 40–50%, and the specific activities of both enzyme preparations were the same within the limits of error of the estimation.     

Creatinine and N-methylhydantoin degradation in two newly isolated Clostridium species

With N-methylhydantoin (NMH) as the main organic substrate, two strictly anaerobic spore forming Gram-positive bacterial strains were isolated from sewage sludge. These strains, named Clostridium sp. FS23 and Clostridium sp. FS41, totally degraded NMH, via N-carbamoylsarcosine (CS) and sarcosine as intermediates. Strain FS23 grew also with creatinine, which was converted to NMH by creatinine iminohydrolase (EC 3.5.4.21). This enzyme was formed at high rates with all substrates tested. Cytosine and 5-fluorocytosine were not utilized as substrates by creatinine iminohydrolase preparations purified to a homogeneity of 98%. NMH amidohydrolase (NMHase) and N-carbamoylsarcosine amidohydrolase (CSHase) turned out to be inducible in both srains. Other than in aerobic organisms, NMHase from these two isolates did not require ATP for enzymatic activity. SH-group protecting agents were not necessary for stability.     

A chemoenzymatic route to mannosamine derivatives bearing different N-acyl groups

The chemoenzymatic route to 2-deoxy-2-propionamido-D-mannose (1b), 2-butyramido-2-deoxy-D-mannose (2b) and 2-deoxy-2-phenylacetamido-D-mannose (3b) involved N-acylation of 2-amino-2-deoxy-D-glucose followed by alkaline C-2 epimerization and selective microbial removal of the epimers with gluco-configuration. The latter step employed whole cells of Rhodococcus equi A4 able to degrade 2-deoxy-2-propionamido-D-glucose (1a), 2-butyramido-2-deoxy-D-glucose (2a) and 2-deoxy-2-phenylacetamido-D-glucose (3a) but inactive towards the corresponding manno-isomers. The metabolism of the gluco-isomers probably involved phosphorylation and subsequent deacylation. 2-Acetamido-2-deoxy-6-O-phospho-D-glucose amidohydrolase [EC 3.5.1.25] but not 2-acetamido-2-deoxy-D-glucose amidohydrolase was detected in the cell extract, the former enzyme being partially purified (15.8-fold with an overall yield of 18.1% and a specific activity of 0.95 units mg-1 protein). According to SDS-PAGE electrophoresis, gel filtration and mass spectrometry, the enzyme was a monomer with an apparent molecular mass of approximately 42 kDa. The optimum temperature and pH of the enzyme were 60 degrees C and 8.0-9.0, respectively. 2-Acetamido-2-deoxy-6-O-phospho-D-glucose and 2-acetamido-2-deoxy-6-O-sulfo-D-glucose but not 2-acetamido-2-deoxy-1-O-phospho-D-glucose or 2-acetamido-2-deoxy-D-glucose were substrates of the enzyme. Its activity was slightly inhibited by the addition of 1 mM Al3+, Ca2+, Co2+, Cu2+, Mn2+ or Zn2+ and activated by 1 mM Mg2+. The concentrated enzyme is highly stable at 4 degrees C in the presence of 0.1 M ammonium sulfate.     

Enzymatic hydrolysis of penicillin V to 6-aminopenicillanic acid byFusarium oxysporum

Summary A strain ofFusarium oxysporum was identified as having an intracellular penicillin V acylase activity (penicillin V amidohydrolase EC 3.5.1.11). Activity was induced by phenoxyacetic acid and had a good tolerance for high substrate and product concentrations. Washed cells could be used repeatedly for the complete hydrolysis of 5% penicillin V solutions. The enzyme was partially purified and concentrated from disrupted cells by fractional precipitation with water miscible solvents.     

Enzymatic production of l-phenylalanine from acetamidocinnamic acid: breeding of an acetamidocinnamate amidohydrolase-hyperproducing mutant

To increase the productivity of l-phenylalanine from acetamidocinnamic acid, we screened bacteria containing high acetamidocinnamate amidohydrolase activity, and strain S-5 containing high activity was isolated from soil. The bacteria were identified as Corynebacterium sp. S-5.When strain S-5 was cultured in a medium containing acetamidocinnamic acid as the sole carbon source or enzyme inducer, the formation of acetamidocinnamate amidohydrolase was observed. This was controlled by catabolite repression. When the strain was cultured in a medium containing glucose and acetamidocinnamic acid as the sole nitrogen source, it showed low acetamidocinnamate amidohydrolase activity and an increased doubling time.To obtain acetamidocinnamate amidohydrolase-hyperproducing strain, we enriched cells growing faster than strain S-5 in a medium containing glucose and acetamidocinnamic acid by continuous culture of mutagenized cells. Mutant C-23 had 12-fold the enzyme production and 3-fold the growth rate of the wild-type strain in a medium containing glucose. Acetamidocinnamate amidohydrolase formation in the mutant did not require acetamidocinnamic acid as enzyme inducer and was resistant to catabolite repression.     

Urease bound to chitin with glutaraldehyde.

The enzyme urease (urea amidohydrolase, EC 3.5.1.5) prepared from Cajanus indicus, has been immobilized with glutaraldehyde-treated chitin as the solid support. The immobilized enzyme was characterized by determining the pH profiles and optimum temperature. Effect of glutaraldehyde concentration on the binding of enzyme to chitin was studied. The storage stability of the chitin-urease system was determined.     

A radiochemical assay for N-acetyl-L-aspartate amidohydrolase (EC 3.5.1.15) and its occurrence in the tissues of the chicken

A simple and rapid radiochemical method for the determination of N-acetyl-L-aspartic acid amidohydrolase (EC 3.5.1.15) activity using ion exchange chromatography has been developed. The activity of this enzyme in the developing brain and some non-nervous tissues of the chicken has been determined. No activity of the enzyme could be detected in the brains of chick embroys prior to 14 days of gestation; activities gradually increased thereafter to adult levels which are about 60% of that found in the adult rat. In non-nervous system tissues of the adult chicken, activities varied from high levels in the kidney to low levels in heart and breast muscle. Treatment of the homogenates of the adult tissues with a detergent significantly increased the enzyme activity, suggesting that a portion of the enzyme is membrane bound.     

Comparison of glutathione S-transferase activity in the rat and birds: tissue distribution and rhythmicity in chicken (Gallus domesticus) liver.

1. Mature, male chickens, Bobwhite quail, and rats differed with respect to glutathione S-transferase (GST) activity in the kidney, duodenum and testis, but species differences were not observed in the liver. 2. GST activity was present in the heart, spleen, liver, duodenum, kidney, testis, cerebral cortex, cerebellum, optic tecta, and medulla oblongata of chickens with differences in tissues and breeds. 3. Renal GST activity was higher in female chickens, whereas enzyme activity in the brain was higher in males. 4. Hepatic GST activity fluctuated about a mean of 784 nmol min-1 mg protein-1 with a 12 hr periodicity which was not a feeding phenomenon. 5. The results demonstrate that GST activity occurs in diverse tissues of the chicken and Bobwhite quail with kidney greater than liver greater than duodenum greater than testis, compared to testis greater than liver greater than duodenum greater than kidney in the rat. Hepatic GST activity exhibits an ultradian periodicity.     

A protein activator of Mg2+-dependent, Ca2+-stimulated ATPase in human erythrocyte membranes distinct from calmodulin

The intracellular localization of aryl acylamidase (aryl-acylamide amidohydrolase, EC 3.5.1.13) in chicken kidney was investigated. By separation on density gradients of the silica sol Ludox AM, the enzyme was localized in the mitochondrial fraction. This mitochondrial fraction was shown to be substantially free of lysosomal contamination. Subfractionation of the purified mitochondria indicates that the enzyme is located on the outer membrane, can be solubilized, and may be a suitable marker enzyme for kidney mitochondria.     

Characterization and partial purification of L-asparaginase from Corynebacterium glutamicum

A high L-asparaginase (L-asparagine amidohydrolase: EC 3.5.1.1) activity was found under conditions of lysine overproduction in cultures of Corynebacterium glutamicum. L-Asparaginase was purified 98-fold by protamine sulphate precipitation. DEAE-Sephacel anion exchange, ammonium sulphate precipitation and Sephacryl S-200 gel filtration. The asparaginase protein was subjected to PAGE under non-denaturing conditions, identified by an in situ reaction and eluted from the gel in an active form. The estimated Mr from gel filtration and SDS-PAGE was 80,000. The L-asparaginase activity was inhibited by the L-asparagine analogue 5-diazo-4-oxo-L-norvaline. Neither D-asparagine nor L-glutamine was a substrate for the enzyme. L-Asparaginase was produced constitutively: its role may be that of an overflow enzyme, converting excess asparagine into aspartic acid, the direct precursor of lysine and threonine.