Lysozyme activity in female genital tissues of normal and genetically lysozyme-deficient rabbits

The internal genitalia of female normal rabbits and mutant lysozyme-deficient rabbits, which lack genetically the leukocytic isozyme of lysozyme, were assayed for lysozyme activity. The ovaries, uteri, and vaginas of the lysozyme-deficient rabbits had less than 20% of the lysozyme activity of normals. The oviducts, and in particular the caudal portions of the oviducts, had lysozyme activities up to 71% of the levels in normals. These observations suggest that the lysozymes of oviduct and leukocytes of rabbits are under the control of different genes.     

Distribution of lysozyme in guinea pigs: Implications for the function of gastrointestinal lysozyme in herbivores

Summary High levels of gastrointestinal lysozyme were present in the stomach of guinea pigs, but not in other portions of the gastrointestinal tract. Because the cecum is the fermentation organ of guinea pigs, these observations call into question the validity of the current hypothesis that the gastrointestinal lysozyme of herbivores functions in the digestion of bacteria from the anterior fermentation organ.Supported in part by grants RR00515 and RR05465 from the National Institutes of Health.     

Lack of distant relationships between lysozyme Ch and hen egg white lysozyme: computer comparison studies

Summary A computer search, made for distant relationships between lysozyme Ch, hen egg white lysozyme, and bacteriophage T4 lysozyme, revealed no unusual similarities in their amino acid sequences. Also, antibodies generated against lysozyme Ch failed to cross react with hen egg white lysozyme and vice versa. These lysozymes most likely represent examples of convergent evolution.Acknowledgments. This research was supported by Public Health Service Grant AI-15531 and the Biomedical Research Support Grant RR-05424.To whom all communication should be addressed.     

A method for automatic recording of serum lysozyme activity with the fragiligraph.

A quick and simple method for the estimation of lysozyme activity using the Fragiligraph, was described. Diminution of turbidity in a suspension of Micrococcus lysodeikticus produced by the addition of standard lysozyme (hen egg white) or serum sample, was continuously recorded for 5 min by the Fragiligraph. The normal mean serum lysozyme activity value obtained by this method is 6,80 mug/ml +/- 1.85.     

Solution structure and activity of mouse lysozyme M

The three-dimensional structure of mouse lysozyme M, glycoside hydrolase, with 130 amino acids has been determined by heteronuclear NMR spectroscopy. We found that mouse lysozyme M had four alpha-helices, two 3(10)helices, and a double- and a triple-stranded anti-parallel beta-sheet, and its structure was very similar to that of hen lysozyme in solution and in the crystalline state. The pH activity profile of p-nitrophenyl penta N-acetyl-beta-D-chitopentaoside hydrolysis by mouse lysozyme M was similar to that of hen lysozyme, but the hydrolytic activity of mouse lysozyme M was lower. From analyses of binding affinities of lysozymes to a substrate analogue and internal motions of lysozymes, we suggest that the lower activity of mouse lysozyme M was due to the larger dissociation constant of its enzyme-substrate complex and the restricted internal backbone motions in the molecule.     

Lysozyme levels in tissues of iron-deficient rats

Fats were fed either diets sufficient (300 ppm) or insufficient (5 ppm) in iron for 10 weeks. The iron-deficient animals had lowered hemoglobin and hematocrit levels and higher levels of kidney lysozyme activity than did control animals. There were no significant changes in serum and spleen lysozyme activity levels.     

A method for automatic recording of serum lysozyme activity with the fragiligraph

Summary A quick and simple method for the estimation of lysozyme activity using the Fragiligraph, was described. Diminution of turbidity in a suspension ofMicrococcus lysodeikticus produced by the addition of standard lysozyme (hen egg white) or serum sample, was continuously recorded for 5 min by the Fragiligraph. The normal mean serum lysozyme activity value obtained by this method is 6,80 g/ml±1.85.We gratefully acknowledge the excellent technical assistence of MissM. Touma.     

Lysozyme levels in tissues of iron-deficient rats

Summary Rats were fed either diets sufficient (300 ppm) or insufficient (5 ppm) in iron for 10 weeks. The iron-deficient animals had lowered hemoglobin and hematocrit levels and higher levels of kidney lysozyme activity than did control animals. There were no significant changes in serum and spleen lysozyme activity levels.Supported in part by grant HL18712-02, Heart and Lung Institute, NIH.     

Common antigenic properties of a g-type (goose) and a c-type (duck) egg white lysozyme: Antibody responses in rabbits and mice

Embden goose (GEWL) and Barbary duck (DEWL) egg white lysozymes possess different amino acid sequences corresponding to the g-type and c-type, respectively. GEWL was shown to be a better immunogen than DEWL in both rabbits and mice. The antigenicity of the two lysozymes was tested using different technique (i.e. indirect ELISA, inhibition tests and immunoabsorption experiments). Injection of either GEWL or DEWL into rabbits and mice induced both specific antibodies and cross-reacting antibodies. Moreover, anti-GEWL antibodies, in contrast to anti-DEWL antibodies, did not cross-react with hen egg white lysozyme (HEWL), a c-type lysozyme. While the structure of GEWL was not modified after binding to plastic, DEWL was denaturated, but it did keep some native epitopes. It was concluded that g-type and c-type lysozymes, which have different amino acid sequences, exhibit strong common antigenic properties.     

A cold-active salmon goose-type lysozyme with high heat tolerance

The Atlantic salmon (Salmo salar) goose-type lysozyme gene was isolated and revealed alternative splicing within exon 2 affecting the signal peptide-encoding region. The lysozyme was produced in Escherichia coli, and the recombinant enzyme showed a high specific lytic activity that was stimulated by low or moderate concentrations of mono- or divalent cations. Relative lytic activities of 70 and 100% were measured at 4°C and 22°C, respectively, and there was no detectable activity at 60°C. However, 30% activity was retained after heating the enzyme for 3 h at 90°C. This unique combination of thermal properties was surprising since the salmon goose-type lysozyme contains no cysteines for protein structure stabilization through disulphide bond formation. The results point to a rapid reversal of inactivation, probably due to instant protein refolding. Received 14 August 2007; received after revision 07 September 2007; accepted 12 September 2007     

The electrophoretic mobility of serum lysozyme.

The electrophoretic mobility of serum lysozyme in 2 patients with raised enzyme levels was identical to that of gamma-globulins. Similar mobility was observed after incubation of lysozyme and normal serum. Incubation with one hypogammaglobulinemic serum showed that lysozyme could also acquire alpha2 mobility.     

Levels of beta-trace protein and lysozyme in human amniotic fluids.

The levels of beta-trace protein and lysozyme were estimated in amniotic fluids from normal fetuses and from fetuses with neuraltube defects. The values of these proteins in normal amniotic fluids were found to be similar to those detected in fetuses with anencephaly and spina bifida. The levels of lysozyme were shown to be correlated with gestational age.     

Structural basis of bacterial defense against g-type lysozyme-based innate immunity

Gram-negative bacteria can produce specific proteinaceous inhibitors to defend themselves against the lytic action of host lysozymes. So far, four different lysozyme inhibitor families have been identified. Here, we report the crystal structure of the Escherichia coli periplasmic lysozyme inhibitor of g-type lysozyme (PliG-Ec) in complex with Atlantic salmon g-type lysozyme (SalG) at a resolution of 0.95 Å, which is exceptionally high for a complex of two proteins. The structure reveals for the first time the mechanism of g-type lysozyme inhibition by the PliG family. The latter contains two specific conserved regions that are essential for its inhibitory activity. The inhibitory complex formation is based on a double ‘key-lock’ mechanism. The first key-lock element is formed by the insertion of two conserved PliG regions into the active site of the lysozyme. The second element is defined by a distinct pocket of PliG accommodating a lysozyme loop. Computational analysis indicates that this pocket represents a suitable site for small molecule binding, which opens an avenue for the development of novel antibacterial agents that suppress the inhibitory activity of PliG.     

Effect of diabetes on the enzymes of the cholinergic system of the rat brain

Summary Choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) activities were determined in several brain regions of normal and streptozotocin-induced diabetic rats. The diabetic rats exhibited significant increase in ChAT activity (p<0.05) in all brain regions studied except for the cortex and the midbrain. Meanwhile, the diabetes condition was associated with significant increase (p<0.05) in AChE activity of the bulbus olfactorius, medulla oblongata and cerebellum. These data suggest that uncontrolled diabetes is associated with significant alterations in the brain cholinergic systems.To whom requests of reprints should be addressed.This work was supported by grants from the National Aeronautics and Space Administration (NSG 2183 and NAG-2-411), a grant from the National Institutes of Health (NIH Grant RR0811) and a grant from the Division of Research Resources, National Institutes of Health (NIH Grant RR03020).     

Levels ofβ-trace protein and lysozyme in human amniotic fluids

Summary The levels of -trace protein and lysozyme were estimated in amniotic fluids from normal fetuses and from fetuses with neuraltube defects. The values of these proteins in normal amniotic fluids were found to be similar to those detected in fetuses with anencephaly and spina bifida. The levels of lysozyme were shown to be correlated with gestational age.     

Successive clutches induced by surgical excision of post-ovulatory oocytes in the lizard Cnemidophorus uniparens.

19 animals had eggs excised from the oviducts soon after ovulation. Number of clutches was nearly tripled in excised animals as compared to controls. An influence of eggs in the oviduct on number of clutches is suggested and may indicate a neuronal link between oviduct and hypothalamus.     

On a rabbit hyperlipemia induced by a fungic galactomannane peptide

Summary I.v. injection into rabbits of a fungic galactomannane peptide isolated from the culture medium ofAspergillus oryzae induced the apparition, 20 h later, of an hypertriglyceridemia, with a concomittant decrease of about 70% of the post-heparin lipoprotein lipase activity. The same effect had been obtained earlier with a carbohydrate-rich fraction purified from a crude papain preparation. The 2 fractions are compared.     

A small chimerically bifunctional monomeric protein: <Emphasis Type="Italic">Tapes japonica</Emphasis> lysozyme

The lysozyme of the marine bilave Tapes japonica (13.8 kDa) is a novel protein. The protein has 46% homology with the destabilase from medicinal leech that has isopeptidase activity. Based on these data, we confirmed hydrolysis activity of T. japonica lysozyme against three substrates: L--Glu-pNA, D--Glu-pNA, and -(-Glu)-L-Lys. The optimal pH of chitinase and isopeptidase activity was 5.0 and 7.0, respectively. The isopeptidase activity was inhibited with serine protease inhibitor, but the lytic and chitinase activities were not. Moreover, only isopeptidase activity is decreased by lyophilization, but lytic and chitinase activities were not. We conclude that T. japonica lysozyme expresses isopeptidase and chitinase activity at different active sites.Received 25 February 2003; received after revision 29 May 2003; accepted 12 June 2003     

Carbonic anhydrase type II in regenerating retinal pigment epithelium. A histochemical study in the rabbit

Type II carbonic anhydrase (CAII) in the cytoplasm of the retinal pigment epithelium (RPE) may contribute to the transport of water and solutes across the RPE. The activity of this enzyme in RPE during its response to damage, e.g., during regeneration, is therefore of interest in understanding retinal disease. Immuno-histochemistry was used to compare CAII activity of normal RPE and RPE experimentally induced to regenerate. In normal rabbits, the RPE stained intensely with a peroxidase-linked antibody specific for human CAII. Regenerating RPE stained less intensely. Within the regenerating epithelium, staining appeared more intense in mature cells than in immature ones, suggesting that CAII activity gradually returns during RPE regeneration.     

Gastric lysozyme as a digestive enzyme in the hoatzin (Opisthocomus hoazin), a ruminant-like folivorous bird

The hoatzin is the only bird known to have pregastric fermentation in the crop. This digestive strategy is supported by morphological and microbiological adaptations analogous to those present in ruminants and ruminant-like mammals. The hoatzin expresses a lysozyme-like bacteriolytic activity in its foregut. The enzyme has a high activity, and its low pH optimum, pepsin resistance and localization to the proventriculus allow it to be active for digestion in the stomach. The hoatzin enzyme and the ruminant gastric lysozyme present similar biochemical characteristics. The lysis of bacterial cells may be of significance for the nutrition of the hoatzin. We propose that the hoatzin expresses a lysozyme which has been recruited to function as a digestive enzyme, representing a unique case of evolutionary convergence of digestive adaptations in this bird and foregut fermenter mammals.