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PubMed2004

Evidence for development of capillary leak syndrome associated with cardiopulmonary bypass in pediatric patients with the homozygous C4A null phenotype.

BACKGROUND: The mechanism of postoperative capillary leak syndrome related to cardiopulmonary bypass (CPB) is unknown. The authors hypothesized that C4 gene polymorphism might be involved in the development of the syndrome because complement activation is associated with CPB and protamine administration, and the two isotypes of C4 (C4A and C4B) differ in their biochemical and functional properties after activation. METHODS: One hundred fifty-six pediatric patients referred for elective cardiac surgery with CPB were included in the study. C4 isotype studies were performed in plasma samples obtained before surgery, with use of agarose gel immunofixation and crossed immunoelectrophoresis. Five possible C4 phenotype groups were observed, which were abbreviated as follows: (1) AABB = no detectable null alleles, (2) A0BB = a single null allele (heterozygous) at the C4A locus, (3) 00BB = a homozygous C4A null allele, (4) AAB0 = a single null allele (heterozygous) at the C4B locus, and (5) AA00 = a homozygous C4B null allele. The patients were classified into five groups according to their C4 phenotypes. Before CPB and at 1 h after CPB, plasma protein was measured with a biuret test kit. Plasma colloid osmotic pressure was determined with a membrane osmometer. Evans blue dye was used to measure plasma volume, serum protein, intravenous protein pool, and transvascular escape rate of Evans blue dye. RESULTS: Of 156 pediatric patients enrolled, 80 were assigned to the AABB group, 28 were assigned to the A0BB group, 7 were assigned to the 00BB group, 31 were assigned to the AAB0 group, and 10 were assigned to the AA00 group, according to their C4 phenotypes. At 1 h after CPB, serum protein concentrations averaged 3.6 +/- 0.4 g/dl in patients with the 00BB C4 phenotype; this value was significantly lower (P < 0.01) than that in patients with other C4 phenotypes. The changes of intravenous protein pool and colloid osmotic pressure were comparable with the change in serum protein concentration. At 1 h after CPB, the transvascular escape rate of Evans blue dye averaged 11.5 +/- 1.3%/h in patients with the 00BB C4 phenotype; this value was significantly higher (P < 0.01) than that in patients with other C4 phenotypes. CONCLUSIONS: In this study, capillary leak syndrome induced by CPB occurred only in patients with the homozygous C4A null phenotype.

Analysis of Variance↗
PubMed1999

In patients with cirrhosis, serum albumin determination should be carried out by immunonephelometry rather than by protein electrophoresis.

OBJECTIVE: Serum albumin is a key parameter for prognosis in cirrhosis. We compared levels of serum albumin determined by both protein electrophoresis and immunonephelometry, with special reference to the Child-Pugh classification. DESIGN AND METHODS: One hundred and thirty-one patients, including 39 with cirrhosis, were included prospectively during 2 months. The aetiology of cirrhosis was mainly alcoholism (67%) and hepatitis C virus (HCV) (18%). Serum albumin was determined simultaneously by electrophoresis (Hydrasys SEBIA following protein determination by the biuret reaction) and by immunonephelometry (BECKMAN Nephelometer). Values were compared by non-parametric tests. RESULTS: For the whole population, electrophoretic and immunonephelometric values correlated (p = 0.85; P < 0.0001), but electrophoresis significantly overestimated serum albumin by a median 1.6 g/l (P < 0.0001) with a large spread in values (range, -3.9 to 12.7). Median overestimation in cirrhosis was 2.6 g/l (P < 0.0001; range, -2.0 to 10.2) and 1.0 g/l (P < 0.0001; range, -3.9 to 12.7) in patients without cirrhosis (difference, P < 0.02). For 6/39 (15.4%) patients with cirrhosis, this overestimation led to an underestimation in the Child-Pugh classification. CONCLUSION: In our experience, electrophoresis can lead to serum albumin values which are significantly different compared to those obtained by immunonephelometry. This discrepancy may lead to an incorrect Child-Pugh classification. Therefore, in the follow-up of cirrhotic patients, serum albumin should be determined by immunonephelometry.

Adult↗
PubMed1999

Evaluation of pulmonary function in workers exposed to hexamethylene diisocyanate.

Production of hexamethylene diisocyanate (HDI) biuret and trimer from HDI monomer was started in 1988 at the plant under study. Pulmonary function tests were included as part of the annual evaluation of the workers in that unit. HDI is expected to have toxic properties similar to those of toluene diisocyanate. The latter has caused accelerated declines in pulmonary function in exposed workers. In 1991, an initial longitudinal evaluation of those pulmonary function tests was performed, comparing annual declines in forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1). The purpose of the study was to evaluate whether or not exposures to HDI at the unit had caused any accelerated decline in FVC or FEV1. No significant differences were seen in that evaluation, but it was decided that the study be continued in a prospective fashion. The study has been continued through 1997. The slope of the annual change in FVC and FEV1 were calculated for a group of workers and a matched control group. The average annual decline in FVC for the exposed group (cases) was 0.026 L, compared with 0.025 L for the control group. For the decline in FEV1, the results were 0.044 L, compared with 0.041 L (P = 0.79). These results are virtually identical and support a conclusion that exposures within this unit to HDI have not caused an accelerated decline in FVC or FEV1. Exposures to HDI were measured during this period. The time-weighted average exposure to HDI during work not requiring respiratory protection in the unit (approximately 2 hours per day) was 0.5 parts per billion. The average daily high peak exposure was 2.9 parts per billion. Exposure to these levels appear to pose no risk of accelerated decline in pulmonary function.

Adult↗
PubMed1980

Model studies on the coordination of copper in biological systems. The deprotonated peptide nitrogen as a potential binding site for copper(II).

1. A large number of potentially bidentate and tridentate amides, X-Y-CONH-Z, were used as model ligands to investigate the complex formation of Cu(II) with the deprotonated peptide nitrogen in biological molecules. A combination of potentiometric titration, spectrophotometry and electron paramagnetic resonance was applied to analyse the structure of the Cu(II) chelates formed at neurtal and basic pH. 2. By systematic variation of the primary binding function X, the ring size of the chelate, and the spatial properties of the C-terminal and N-terminal substituents, three classes of amide ligands could be established with reference to their capacity for Cu(II)-induced deprotonation of NHCO and metal binding. 3. Under physiological conditions of pH, peptide (class A) chelates are only formed by those bidentate amide ligands with X being an imidazole (sp2) nitrogen or a terminal (sp3) amino nitrogen. Mercaptide sulfur must also be considered to belong in this group of strong copper(II)-binding sites, but in our low-molecular-weight model ligands the redox equilibrium 2 Cu(II) + 2 RSH in equilibrium or formed from 2 CU(II) + RSSR + 2 H+ interferes, yielding insoluble Cu(I)-S polymers above pH 4. In addition to the unidentate binding strength of X, entropy effects play an important role. Depending on whether X is an imidazole or amino nitrogen, only five-membered or six-membered monocyclic chelate structures respectively cause coordination of the deprotonated peptide function. 4. Biuret (class B) Cu(II) chelates are only formed under non-physiological conditions at pH > 11.5 producing the well known violet chromophores CuIIN4(-). In general these complexes, which also include the Cu(II) biguanides, show a clearly resolved electron paramagnetic resonance spectrum with nitrogen superhyperfine structure. 5. A third class of peptide model ligands (class C) consists of those amides where the CuII-X bond does not provide enough thermodynamic stability. The binding site of these class C amides includes functional groups such as carboxylate (COO-), methionine sulfur (RSR'), aliphatic or aromatic hydroxyl (OH) and amide nitrogen (NHCO) itself. When X is a pyridine (sp2) nitrogen or an amino (sp3) nitrogen, NHCO deprotonation is only promoted in five-membered but not six-membered ring chelates. On the other hand, a combination of COO- and NH2, as in asparagine, will allow deprotonation of NHCO in the presence of Cu(II). And third, despite a pronounced unidentate affinity of the imidazole nitrogen for Cu(II), N-acetylhistamine acts as a class C amine, in contrast to imidazolylacetamide, which forms a stable Cu(II) peptide chelate. This difference in Cu binding is explained on the basis of space-filling models. These clearly demonstrate that in the case of the 2:1 complex of Cu(II) with N-acetylhistamine, the planarity of the ionised peptide function can not be retained in a square planar arrangement of the two amide ligands around the copper center.

Amides↗
PubMed1987

Determination of total protein in human seminal plasma.

Methodological problems are encountered in determinating human seminal protein content since results are influenced especially by techniques which are used, and by modifications due to liquefaction process. In order to test these two points, three methods (Folin, Biuret and Meulemans's reactions) were applied to the same seminal samples and results were compared. The differences seem principally due to the high level of glycoproteins. To determine the modifications of total protein content with time after semen collection, each sample was separated in aliquot fractions and proteolysis was blocked at different times for each fraction. There is an increase of the protein concentration during the first fifteen minutes that follows semen collection. The cause of this phenomenon is discussed.

Electrophoresis↗
PubMedDate not supplied

Ascorbic acid levels of aqueous humor of dogs after experimental phacoemulsification.

Phacoemulsification has been successfully employed in humans and animals for lens extraction. This ultrasonic extracapsular surgical technique induces hydroxyl radical formation in the anterior chamber, which accumulates despite irrigation and aspiration. In this paper we determined the total antioxidant status of aqueous humor after phacoemulsification by measuring aqueous humor ascorbic acid levels. Mixed-breed dogs (n = 11; weighing about 10 kg) with normal eyes as determined by slit-lamp biomicroscopy, applanation tonometry, and indirect ophthalmoscopy had phacoemulsification performed in one eye with the other eye used as a control. Samples of aqueous humor were obtained by anterior chamber paracentesis before surgery and at days 1, 2, 3, 7, and 15 after surgery. Total aqueous humor antioxidant status was inferred from the capacity of aqueous humor to inhibit free radical generation by 2,2-azobis (2-amidopropane) chlorine. Ascorbic acid concentrations were measured by high-pressure liquid chromatography with UV detection. Protein content was determined with the biuret reagent. Statistical analysis was performed by anova followed by the paired t-test. Total antioxidant capacity was reduced from 48 to 27 min during the first 24 h with a gradual increase thereafter, remaining statistically lower than the control eye until 7 days postoperatively. Reduced levels of ascorbic acid followed this reduction in antioxidant capacity (from 211 to 99 microm after 24 h), remaining lower than the control eye until 15 days postoperatively. Protein concentration in aqueous humor increased from 0.62 mg/mL to 30.8 mg/mL 24 h after surgery, remaining statistically lower than the control eye until 15 days postoperatively. Paracentesis alone did not significantly alter the parameters measured. These results indicate that after phacoemulsification, the aqueous humor ascorbic acid levels and antioxidant defenses in aqueous humor are reduced, indirectly corroborating free radical production in the anterior chamber as a result of phacoemulsification. The inflammatory process consequent to the surgical procedure demonstrated by increased protein content in aqueous humor can also contribute to free radical production and ascorbic acid consumption.

Animals↗
PubMed1998

Cutaneous sensitization to some polyisocyanate prepolymers in guinea pigs.

Isocyanates are used extensively in the polyurethane industry. Pulmonary and dermal sensitization resulting from exposure to diisocyanates has frequently been reported, but the potential effects of polyisocyanates on health are less well known. Thus, since 1978, occupational exposure limits have been established for diisocyanates only. Nevertheless, respiratory diseases and dermatitis have been reported in the polyurethane industry after accidental isocyanate contact during spills or splashes. The aim of this experimental work was to assess the dermal hypersensitivity of guinea pigs to some polyisocyanate prepolymers by means of a well-conducted standard predictive Buehler test. Our results showed that dicyclohexylmethane 4,4'-diisocyanate (HMDI), toluylene 2,4-diisocyanate (TDI), TDI adduct triol, TDI isocyanurate, 1,6-hexamethylene diisocyanate (HDI), HDI isocyanurate, HDI biuret and isophorone diisocyanate (IPDI) induced dermal sensitization while IPDI isocyanurate did not. In conclusion, the dermal hypersensitivity of guinea pigs to some polyisocyanates was similar to those of their corresponding monomers except for IPDI isocyanurate, suggesting that the results from diisocyanate monomers could not be a valuable approach for the detection of the sensitization potency of the corresponding prepolymers.

Animals↗
PubMed1985

Synthetic polymers as drugs.

Biologically active compounds have been incorporated into synthetic polymers. Bithionol, a well-known and potent antibacterial agent, has been used as bisphenol monomers for polyesters, polyphosphates, and phosphonates; the bischloroformate of bithionol has been converted into copolycarbonates and polyurethanes. The copolycarbonates of bithionol, optimally designed polymer structures with poly(ethylene oxide) glycols as the other comonomer, have been hydrolyzed under physiological conditions at a degradation rate of about 1% per day. Primaquine, an antimalarial, and amantadine, an antiviral agent, when reacted with isocyanates gave polymeric biurets as do other primary aliphatic amines. Primaquine also underwent nucleophilic substitution reactions on polyepichlorohydrin. 3-Vinyl-, 4-vinyl-, and 5-vinylsalicylic acids have been synthesized, polymerized, and copolymerized to polymeric antibacterials. Copolymers of vinylsalicylic acid can be selective in their activity, depending on the comonomer. Selectivity can also be achieved by derivation of the poly(vinylsalicylic acid).

Anti-Bacterial Agents↗
PubMed1985

Serum protein reference values in foals during the first year of life: comparison of chemical and electrophoretic methods.

Normal reference values for serum proteins of foals from birth to 1 year of age have been established. Chemical and electrophoretic/refractometric methods for total protein, albumin, total globulin and Albumin/Globulin (A/G ratio) have also been compared. The biuret total protein method and Bromcresol Green (BCG) method on the Technicon SMA 12/60 autoanalyzer were used and compared with total protein determined via refractometry and albumin determined by Cellulose Acetate (CA) electrophoresis/densitometry. Globulin and A/G ratios were calculated from the chemical method data and compared with that obtained electrophoretically. Total protein, albumin, total globulins and A/G ratios all were in agreement at all sample times studied. Data on the subfractionation of serum globulins via CA electrophoresis is also presented. Wide variations in alpha and beta globulin levels were noted among the foal sera early in life. As a result, two distinct populations of foals with respect to both globulin content and A/G ratio were identified. One of these populations (Group A) appeared to have obtained passive immunity more slowly than the other (Group B) animals. Comparison of these data with clinical cases of foals in which failure of passive transfer was a part suggests that the A/G ratio may be useful in assessing adequate colostral antibody levels in the newborn foal.

Journal Article↗
PubMed2006

Reference intervals for hematologic and biochemical constituents and protein electrophoretic fractions in captive common buzzards (Buteo buteo).

BACKGROUND: Increasing interest in wildlife care leads to the need for new tools to evaluate animal health. Laboratory investigations require reference intervals against which to compare the results obtained. For common buzzards, only a few studies have been performed to establish hematologic and biochemical reference intervals. OBJECTIVES: The aim of this work was to develop reference values for routine hematologic and biochemical constituents and protein electrophoretic fractions and evaluate possible seasonal differences in values for healthy common buzzards. METHODS: Heparinized blood samples were collected from 23 captive, clinically healthy common buzzards between February 2001 and June 2003. A CBC, routine biochemical analysis, and protein electrophoresis were performed. Data distribution was assessed and results from birds sampled in spring, summer, and winter were compared. Results from alternative methods for hemoglobin (Hgb; estimated as HCT / 3 vs spectrophotometry), total protein (biuret vs refractometry), and albumin (bromcresol green vs electrophoresis) concentrations also were compared. RESULTS: Reference intervals were calculated as 10-90th percentiles. In spring and summer, total WBC and heterophil counts, and urea, total protein, prealbumin, and beta- and gamma-globulins concentrations were significantly different from winter values. Results obtained by alternative methods for Hgb, total protein, and albumin concentrations were significantly different from those obtained by standard methods, although estimated and spectrophotometric Hgb values were significantly correlated. CONCLUSIONS: The reference values obtained in this study for hematologic and plasma biochemical constituents and their seasonal variation in healthy, captive common buzzards will be useful in the clinical evaluation of these birds in rehabilitation settings.

Animals↗
PubMed1981

Reference values for equine peritoneal fluid.

Twenty horses, aged one to 17 years (mean age 6 years), presented for elective destruction and subsequently found at autopsy to have no significant peritoneal alterations, were used to determine a variety of reference values for peritoneal fluid. Samples were collected ante mortem or within 1 h post mortem. Each cavity contained 100 to 300 ml of usually clear, pale yellow fluid which in a clinical refractometer showed a mean specific gravity 1.010 (range 1.0081-1.0116) and mean (+/- standard deviation) total protein 7.7 +/- 3.6 g/litre. The mean total nucleated cell count (+/- sd) was 4.33 +/- 2.5 x 10(9)/litre (range 1.5-10.1 x 10(9)/litre) and, proportionally, polymorphonuclear leucocytes averaged 45.2 per cent, mononuclear phagocytes 47 per cent, lymphocytes 7.8 per cent, eosinophils 0.7 per cent and basophils and mast cells zero. Eosinophils were not usually seen but 6 samples had 1 to 5 per cent. The peritoneal fluid chemical profile (mean +/- sd) was: Aspartate aminotransferase (AST) 118.9 +/- 46.9 iu/litre; alkaline phosphatase (AP) 56.0 +/- 52.7 iu/litre; lactate dehydrogenase (LDH) 143.0 +/- 106.1 iu/litre; total bilirubin (TB) 8.0 +/- 6.2 mumol/litre; total protein (TP) (biuret method) 14.2 +/- 6.8 g/litre; urea nitrogen (BUN) 6.1 +/- 1.1 mmol/litre; glucose 7.7 +/- 1.8 mmol/litre; inorganic phosphate (IP) 1.4 +/- 0.5 mmol/litre; calcium 2.0 +/- 0.2 mmol/litre. TP, BUN, glucose and IP were closely correlated with levels in paired serum samples.

Animals↗
PubMed1990

Peritoneal fluid values from healthy foals.

Peritoneal fluid was analysed from 17 foals, aged 13 to 134 days with a mean age of 68 days. Cytologically, the peritoneal fluid was characterised by a mean total cell count of 0.45 x 10(9)/litre (range 0.06 to 1.42 x 10(9)/litre), rare eosinophils, rare cytophagia and variable percentages of neutrophils and mononuclear cells. These data indicate that peritoneal fluid nucleated cell counts over 1.50 x 10(9)/litre in the foal should be interpreted as elevated. Biochemical evaluation revealed a mean biuret protein level of 12 g/litre, mean refractive index protein level of 16 g/litre and urea nitrogen concentration of 1.96 mmol/litre. There was no correlation between the foals' white blood cell and peritoneal fluid nucleated cell counts. Results of this study indicate that adult horse reference values for evaluation of peritoneal fluid are of questionable validity for foals. Diagnostically, the most important observation was that maximum peritoneal fluid nucleated cell counts in healthy foals were much lower than reported maximal reference values for adult horses (1.5 x 10(9)/litre versus 5.0 x 10(9)/litre or 10.0 x 10(9)/litre).

Animals↗
PubMed1979

The assay and stability of chlorpropamide in solid dispersion with urea.

Thin layer chromatography followed by reflectance densitometry has been used to evaluate the stability of chlorpropamide-urea during the fusion process. Urea was found to decompose to biuret and chlorpropamide to p-chlorobenzenesulphonamide: several other unidentified decomposition products were detected. The energy for decomposition of chlorpropamide was 57.1 kJmol-1 for melts containing 15 and 30% chlorpropamide. Decomposition followed apparent first order kinetics.

Chlorpropamide↗
PubMed1987

Solubilization of Leonardite by an Extracellular Fraction from Coriolus versicolor.

Coriolus versicolor has previously been shown to degrade leonardite, an oxidized form of lignite. An extracellular fraction containing protein purified from a C. versicolor culture solubilized leonardite in vitro. Expression of the activity did not require the presence of leonardite and appeared during idiophase. During ion-exchange and gel filtration column chromatography, leonardite-biosolubilizing activity eluted with syringaldazine oxidase activity and with protein, as measured by A(280) and the biuret protein assay. Syringaldazine is a substrate of the polyphenol oxidase formed by C. versicolor. Comparison of leonardite-biosolubilizing activity with the effects of chelators and surface-active agents on leonardite showed that biosolubilization was not due to either surfactant or chelating ability. Heat treatment of the preparation at 60 degrees C for 30 min significantly reduced both syringaldazine oxidase and leonardite-biosolubilizing activities. Cyanide, azide, and thioglycolate, which are known inhibitors of syringaldazine oxidase activity of C. versicolor, also inhibited leonardite biosolubilization. From these data, we conclude that the purified protein fraction from C. versicolor contains a syringaldazine oxidase activity that participates in leonardite biosolubilization by enzymatic action.

Journal Article↗
PubMed1995

Degradation and mineralization of atrazine by a soil bacterial isolate.

An atrazine-degrading bacterial culture was isolated from an agricultural soil previously impacted by herbicide spills. The organism was capable of using atrazine under aerobic conditions as the sole source of C and N. Cyanuric acid could replace atrazine as the sole source of N, indicating that the organism was capable of ring cleavage. Ring cleavage was confirmed in 14CO2 evolution experiments with [U-14C-ring]atrazine. Between 40 and 50% of ring-14C was mineralized to 14CO2. [14C]biuret and [14C]urea were detected in spent culture media. Cellular assimilation of 14C was negligible, in keeping with the fully oxidized valence of the ring carbon. Chloride release was stoichiometric. The formation of ammonium during atrazine degradation was below the stoichiometric amount, suggesting a deficit due to cellular assimilation and metabolite-N accumulation. With excess glucose and with atrazine as the sole N source, free ammonium was not detected, suggesting assimilation into biomass. The organism degraded atrazine anaerobically in media which contained (i) atrazine only, (ii) atrazine and glucose, and (iii) atrazine, glucose, and nitrate. To date, this is the first report of a pure bacterial isolate with the ability to cleave the s-triazine ring structure of atrazine. It was also concluded that this bacterium was capable of dealkylation, dechlorination, and deamination in addition to ring cleavage.

Atrazine↗
PubMed1972

Immunochemical parameters of some commercial conjugates for the fluorescent treponemal antibody-absorption test.

Fluorescein-labeled anti-human globulins were examined to determine the need for standardization of conjugates used in the fluorescent treponemal antibody-absorption (FTA-ABS) test. Twenty-one of 33 conjugates submitted by commercial manufacturers to the Reagents Control Activity, Venereal Disease Research Laboratory, for evaluation in the FTA-ABS test were available for study. Conjugates, after evaluation in FTA-ABS performance tests, were examined by immunoelectrophoresis, by titration against immunoglobulins G and M (IgG, IgM) with FTA-ABS techniques, and by the biuret protein and fluorescein diacetate methods for determining fluorescein to protein (F/P) ratios. The conjugates were predominately anti-IgG globulin with anti-light-chain activity. Differences were noted in the ability of some conjugates to detect IgM antibody. The F/P ratios of those conjugates that could be determined varied from 2.6 to 17.8 mug of fluorescein per mg of protein. The need to identify and standardize both the immunologic capabilities and the optimum F/P ratio for FTA-ABS test conjugates is presented.

Animals↗
PubMed2005

Purification and characterization of allophanate hydrolase (AtzF) from Pseudomonas sp. strain ADP.

AtzF, allophanate hydrolase, is a recently discovered member of the amidase signature family that catalyzes the terminal reaction during metabolism of s-triazine ring compounds by bacteria. In the present study, the atzF gene from Pseudomonas sp. strain ADP was cloned and expressed as a His-tagged protein, and the protein was purified and characterized. AtzF had a deduced subunit molecular mass of 66,223, based on the gene sequence, and an estimated holoenzyme molecular mass of 260,000. The active protein did not contain detectable metals or organic cofactors. Purified AtzF hydrolyzed allophanate with a k(cat)/K(m) of 1.1 x 10(4) s(-1) M(-1), and 2 mol of ammonia was released per mol allophanate. The substrate range of AtzF was very narrow. Urea, biuret, hydroxyurea, methylcarbamate, and other structurally analogous compounds were not substrates for AtzF. Only malonamate, which strongly inhibited allophanate hydrolysis, was an alternative substrate, with a greatly reduced k(cat)/K(m) of 21 s(-1) M(-1). Data suggested that the AtzF catalytic cycle proceeds through a covalent substrate-enzyme intermediate. AtzF reacts with malonamate and hydroxylamine to generate malonohydroxamate, potentially derived from hydroxylamine capture of an enzyme-tethered acyl group. Three putative catalytically important residues, one lysine and two serines, were altered by site-directed mutagenesis, each with complete loss of enzyme activity. The identity of a putative serine nucleophile was probed using phenyl phosphorodiamidate that was shown to be a time-dependent inhibitor of AtzF. Inhibition was due to phosphoroamidation of Ser189 as shown by liquid chromatography/matrix-assisted laser desorption ionization mass spectrometry. The modified residue corresponds in sequence alignments to the nucleophilic serine previously identified in other members of the amidase signature family. Thus, AtzF affects the cleavage of three carbon-to-nitrogen bonds via a mechanism similar to that of enzymes catalyzing single-amide-bond cleavage reactions. AtzF orthologs appear to be widespread among bacteria.

Allophanate Hydrolase↗