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A Meinhardt

Publications and source records attributed to A Meinhardt.

At least 19 recordsLinked to original sources
PubMed1999

Serum albumin as a potential carrier for the apocrine secretion of proteins in the rat coagulating gland.

A protein of 66k was purified to homogeneity from the total secretion of rat coagulating gland. Its close structural relationship to serum albumin was demonstrated by N-terminal amino acid sequence analysis, proteolytic fingerprinting and Western blotting studies using polyclonal antibodies raised against the 66k protein and rat serum albumin. Immunofluorescence staining showed that the 66k protein was localised in the cytoplasm of coagulating gland epithelial cells from which it is released via apocrine blebs. Performing immunoelectron microscopy, the 66k protein was by no means detectable in the endoplasmic reticulum and the Golgi apparatus. Reverse transcription-PCR, Northern blotting studies and in situ hybridisation experiments demonstrated that mRNA of albumin is not expressed by coagulating gland epithelial cells. Therefore, intravascular albumin should be transferred into the epithelial cells of the rat coagulating gland followed by secretion via aposomes. Furthermore, overlay blots proved that the 66k protein binds to the apocrine proteins carbonic anhydrase II and secretory transglutaminase and vice versa. In contrast, no binding was evident to the merocrine 115k protein and to cytoplasmic resident proteins e.g. lactate dehydrogenase. These findings point to the assumption that serum albumin taken up from extracellular sources could function as a selective carrier for cytoplasmic proteins destined for apocrine secretion.

Animals↗
PubMed1999

A switch in the cellular localization of macrophage migration inhibitory factor in the rat testis after ethane dimethane sulfonate treatment.

Macrophage migration inhibitory factor (MIF), one of the first cytokines to be discovered, has recently been localized to the Leydig cells in adult rat testes. In the following study, the response of MIF to Leydig cell ablation by the Leydig cell-specific toxin ethane dimethane sulfonate (EDS) was examined in adult male rats. Testicular MIF mRNA and protein in testicular interstitial fluid measured by ELISA and western blot were only marginally reduced by EDS treatment, in spite of the fact that the Leydig cells were completely destroyed within 7 days. Immunohistochemistry using an affinity-purified anti-mouse MIF antibody localized MIF exclusively to the Leydig cells in control testes. At 7 days post-EDS treatment, there were no MIF immunopositive Leydig cells in the interstitium, although distinct MIF immunostaining was observed in the seminiferous tubules, principally in Sertoli cells and residual cytoplasm, and some spermatogonia. A few peritubular and perivascular cells were also labelled at this time, which possibly represented mesenchymal Leydig cell precursors. At 14 and 21 days, Sertoli cell MIF immunoreactivity was observed in only a few tubule cross-sections, while some peritubular and perivascular mesenchymal cells and the re-populating immature Leydig cells were intensely labeled. At 28 days after EDS-treatment, the MIF immunostaining pattern was identical to that of untreated and control testes. The switch in the compartmentalization of MIF protein at 7 days after EDS-treatment was confirmed by western blot analysis of interstitial tissue and seminiferous tubules separated by mechanical dissection. These data establish that Leydig cell-depleted testes continue to produce MIF, and suggest the existence of a mechanism of compensatory cytokine production involving the Sertoli cells. This represents the first demonstration of a hitherto unsuspected pattern of cellular interaction between the Leydig cells and the seminiferous tubules which is consistent with an essential role for MIF in male testicular function.

Animals↗
PubMed1999

An essential role for macrophage migration inhibitory factor (MIF) in angiogenesis and the growth of a murine lymphoma.

BACKGROUND: Macrophage migration inhibitory factor (MIF) has been shown to counterregulate glucocorticoid action and to play an essential role in the activation of macrophages and T cells in vivo. MIF also may function as an autocrine growth factor in certain cell systems. We have explored the role of MIF in the growth of the 38C13 B cell lymphoma in C3H/HeN mice, a well-characterized syngeneic model for the study of solid tumor biology. MATERIALS AND METHODS: Tumor-bearing mice were treated with a neutralizing anti-MIF monoclonal antibody and the tumor response assessed grossly and histologically. Tumor capillaries were enumerated by immunohistochemistry and analyzed for MIF expression. The effect of MIF on endothelial cell proliferation was studied in vitro, utilizing both specific antibody and antisense oligonucleotide constructs. The role of MIF in angiogenesis also was examined in a standard Matrigel model of new blood vessel formation in vivo. RESULTS: The administration of anti-MIF monoclonal antibodies to mice was found to reduce significantly the growth and the vascularization of the 38C13 B cell lymphoma. By immunohistochemistry, MIF was expressed predominantly within the tumor-associated neovasculature. Cultured microvascular endothelial cells, but not 38C13 B cells, produced MIF protein and required its activity for proliferation in vitro. Anti-MIF monoclonal antibody also was found to markedly inhibit the neovascularization response elicited by Matrigel implantation. CONCLUSION: These data significantly expand the role of MIF in host responses, and suggest a new target for the development of anti-neoplastic agents that inhibit tumor neovascularization.

Animals↗
PubMed1998

Pharmacological intervention in age-associated brain disorders by Flupirtine: Alzheimer's and prion diseases.

Alzheimer's disease, a major form of dementia in the elderly has become an increasingly important health problem in developed countries. In vitro studies on primary neurons demonstrate that Flupirtine (Katadolon) at a concentration of 1 microg/ml, significantly reduces the neurotoxic (apoptotic) effect displayed by A beta25-35, a segment of the amyloid beta-protein precursor the etiologic agent of Alzheimer's disease. Flupirtine, which has been in clinical use since 10 years ago, prevents the toxic effect of PrP, the presumed etiologic agent of the Creutzfeldt-Jakob disease as well as the excitatory amino acid glutamate on cortical neurons. Flupirtine displays a bimodal activity. Its strongest cytoprotective effect against glutamate-induced neurotoxicity was measured if administered at least 120 min prior to the addition of the glutamate. A likewise potent anti-apoptotic activity was measured if cells were simultaneously incubated with Flupirtine and the apoptotic inducers. Administration of Flupirtine during postincubation time in the experiments with glutamate did not result in neuroprotection. In parallel with the determination of the effect of Flupirtine on the toxin (A beta, PrP or glutamate)-induced neuronal death the effect of the drug on the intracellular Ca2+ level [Ca2+]i, was measured. It is well established that incubation of neurons with glutamate causes an increase in [Ca2+]i. It was found that a simultaneous administration of Flupirtine and glutamate did not reduce the glutamate-induced high Ca2+ level. Only if the cells had been preincubated for approximately 30 min with the drug the intracellular Ca2+ level was significantly lower. Experimental evidence given here shows that the molecular basis for the antiapoptotic effect of Flupirtine against glutamate, triggered during pre-incubation, is an increased expression of the protooncogene bcl-2. The neuroprotective effect determined during coincubation with the inducer is attributed to a normalization of the glutathione level which dropped in the presence of the inducers. It is concluded that Flupirtine is a promising drug to treat neurodegenerative disorders occurring with age, e.g. Alzheimer's disease and prion based diseases, like Creutzfeldt-Jakob disease. This conclusion is corroborated by the favourable pharmacokinetic profile of Flupirtine.

Aging↗
PubMed1998

Hormonal regulation and germ cell-specific expression of heat shock protein 60 (hsp60) in the testis of macaque monkeys (Macaca mulatta and M. fascicularis).

Decrease of heat shock protein 60 (hsp60), a mitochondrial chaperonin, in germ cells of men has been shown to be associated with low spermatogenic efficiency. In the present study, we have investigated the hormonal regulation of hsp60 in a pre-clinical primate animal model. Hsp60 production in the testes of the intact cynomolgus monkey (Macaca fascicularis) and animals that had been treated with the GnRH antagonist Cetrorelix for 25 days was studied by immunohistochemistry. In addition, testes of untreated adult rhesus monkeys (Macaca mulatta) and immature animals either exposed to human chorionic gonadotrophin (hCG), human follicle stimulating hormone (FSH) or hCG and FSH in combination, as well as vehicle-treated controls were analysed. In adult monkeys, specific hsp60 staining was observed in Leydig cells, spermatogonia and early primary spermatocytes. The labelling in Sertoli cells was not stage dependent. The hsp60 staining pattern was unaffected by gonadotrophin releasing hormone (GnRH) antagonist treatment. Western blot analysis confirmed the presence of a single band of 60 kDa in testicular homogenates of the cynomolgus monkey. In the testis of immature rhesus monkeys, hsp60 immunoreactivity was visible in gonocytes, spermatogonia and in Sertoli cells, whereas interstitial cells were negative. In the experimental study, hCG alone or in combination with FSH caused a substantial and marked upregulation of the chaperonin in Leydig cells. Human FSH alone did not affect hsp60 expression. We conclude that hCG is an important regulator of Leydig cell hsp60 expression during development, whereas FSH in immature animals and GnRH in adult monkeys is of less importance.

Animals↗
PubMed1998

Spermatogenesis.

Spermatogenesis is a complex process involving mitotic cell division, meiosis and the process of spermiogenesis. The regulation of spermatogenesis involves both endocrine and paracrine mechanisms. The endocrine stimulation of spermatogenesis involves both follicle stimulating hormone (FSH) and luteinizing hormone, the latter acting through the intermediary testosterone, produced by the Leydig cells in the testis. Since the germ cells do not possess receptors for FSH and testosterone, the hormonal signals are transduced through the Sertoli cells and peritubular cells by the production of signals that have yet to be defined. Although the hormonal signals are essential for successful spermatogenesis, there is increasing evidence that a multiplicity of growth factors and cytokines are involved in local control mechanisms influencing stem cell renewal by mitosis and the complicated process of the two meiotic cell divisions. The final complex metamorphosis which converts a round cell into the complex structures of the spermatozoa is well defined at a structural level, but the control systems regulating this process still remain to be elucidated.

Animals↗
PubMed1998

Local regulation of macrophage subsets in the adult rat testis: examination of the roles of the seminiferous tubules, testosterone, and macrophage-migration inhibitory factor.

In the adult rat testis, macrophages belong to one of two subsets differentiated by expression or lack of expression of the resident macrophage surface antigen recognized by monoclonal antibody ED2. Local regulation of the testicular macrophage subsets was investigated in normal and 4-wk experimentally cryptorchid adult rats with and without s.c. testosterone implants (T-implants). Macrophage subsets ED2(+) (resident-type) and ED2(-) (monocyte-like) were identified immunohistochemically and counted in perfusion-fixed frozen testis sections. Depletion of the spermatogenic cells by cryptorchidism had no effect on testicular macrophage numbers. Inhibition of Leydig cell and seminiferous tubule function by low-dose (3 cm) T-implants caused a 40% reduction in ED2(+) resident macrophages in both scrotal and abdominal testes. High-dose (24 cm) T-implants, which inhibit Leydig cell function while maintaining normal seminiferous tubule function, also reduced the number of resident macrophages by approximately 40%, although this reduction was at least partially prevented in the abdominal testes. In the scrotal testis only, the ED2(-) monocyte/macrophage subset was significantly reduced in number by low-dose, but not high-dose, T-implants. The concentration of the Leydig cell-secreted cytokine macrophage-migration inhibitory factor (MIF) in testicular fluid was reduced by cryptorchidism, but not by the T-implants. When data from all experimental groups were combined, ED2(+) resident macrophage numbers showed a significant positive correlation with parameters of Leydig cell function (serum LH and testicular testosterone levels) but a negative correlation with MIF levels. This study indicates that Leydig cells regulate testicular macrophage numbers directly, rather than via an effect upon the seminiferous epithelium, in the adult rat testis. The data also suggest that testosterone and MIF play only a minor role, if any, in this regulation.

Animals↗
PubMed1998

Cytoplasmic carbonic anhydrase II of rat coagulating gland is secreted via the apocrine export mode.

Two different pathways for protein secretion are described for epithelial cells of rat coagulating gland and dorsal prostate: the classical merocrine and the alternative apocrine release mode. Apocrine-secreted proteins are synthesized on cytoplasmic polyribosomes and are subsequently exported in protrusions on the apical cell surface (aposomes). In this article we report the identification and purification to homogeneity of a 29-kD protein from the secretion of rat coagulating gland. N-terminal amino acid sequence analyses revealed 100% identity to rat brain carbonic anhydrase II (CAH II). In addition, the 29-kD protein showed CAH enzyme activity. On Western blot analysis, a polyclonal anti-CAH II antibody raised in rabbit reacted specifically with the rat and human but not bovine CAH II isoforms. Immunohistochemical studies on rat coagulating gland showed strong labeling for CAH II protein in aposomes. Immunoelectron microscopy confined CAH II protein to the cytoplasm and aposomes, whereas no staining was visible in the compartments of the classical merocrine route, the endoplasmic reticulum and Golgi apparatus. The resident cytoplasmic protein lactate dehydrogenase, however, was not found in the secretion. Taken together, the morphological and biochemical data clearly indicate that cytoplasmic CAH II from rat coagulating gland is specifically selected and then secreted via the apocrine pathway.

Amino Acid Sequence↗
PubMed1998

Localization of follistatin in the rat testis.

The cellular localization of the activin-binding protein, follistatin, in the rat testis has been a matter of some controversy with different investigators claiming that Sertoli cells, Leydig cells or germ cells are the primary cell types containing this protein. The localization of mRNA encoding follistatin was re-examined using reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization as well as the distribution of follistatin by immunohistochemistry. The results demonstrate that mRNA encoding follistatin is located in many germ cells including type B spermatogonia, primary spermatocytes with the exception of the late leptotene and early zygotene stages, and spermatids at steps 1 to 11. It is also found in Sertoli cells and endothelial cells but not in Leydig cells. Immunohistochemistry, using two different antisera to follistatin, showed that this protein was localized to spermatogonia, primary spermatocytes at all stages except the zygotene stage, spermatids at all stages and to endothelial cells and Leydig cells in the intratubular regions. The failure to detect mRNA for follistatin in Leydig cells using RT-PCR and in situ hybridization suggests that the immunohistochemical localization in these cells reflects binding of follistatin produced elsewhere. The widespread localization of follistatin, taken together with its capacity to neutralize the actions of activin, may indicate that follistatin modulates a range of testicular actions of activin, many of which remain unknown.

Animals↗
PubMed1998

MIF expression in the rat brain: implications for neuronal function.

BACKGROUND: The mediator known historically as macrophage migration inhibitory factor (MIF) has been identified recently as being released into the circulation by the anterior pituitary gland as a consequence of stress or during a systemic inflammatory response. Macrophages and T cells also secrete MIF, both in response to proinflammatory factors or upon stimulation with glucocorticoids. Once released, MIF "overrides" or counterregulates the immunosuppressive effects of steroids on cytokine production and immune cellular activation. To further investigate the biology of MIF and its role in the neuroendocrine system, we have studied the regional and cellular expression of MIF in brain tissue obtained from normal rats and rats administered LPS intracisternally. MATERIALS AND METHODS: Rat brain sections were analyzed by immunohistochemistry utilizing an affinity-purified, anti-MIF antibody raised to recombinant MIF, and by in situ hybridization using a digoxigenin-labeled, antisense MIF cRNA probe. The kinetics of MIF mRNA expression in brain were compared with that of IL-1, IL-6, and TNF-alpha by RT-PCR of total brain RNA. The cerebrospinal fluid content of MIF and TNF-alpha proteins was analyzed by Western blotting and ELISA. RESULTS: A strong baseline expression pattern for MIF was observed in neurons of the cortex, hypothalamus, hippocampus, cerebellum, and pons. By in situ hybridization, MIF mRNA was found predominantly in cell bodies whereas MIF protein was detected mostly within the terminal fields associated with neurons. There was a marked pattern of MIF immunoreactivity within the mossy fibers of the dentate gyrus and dendrites of the hippocampal CA3 field. These structures have been shown previously to be involved in glucocorticoid-induced tissue damage within the hippocampus, suggesting an association between MIF and targets of glucocorticoid action. The intracisternal injection of LPS increased MIF mRNA and protein expression in brain and MIF immunoreactivity was due in part to infiltrating monocytes/macrophages. MIF protein also was found to be rapidly released into the cerebrospinal fluid. This response corresponded with that of LPS-induced cytokine release and MIF mRNA expression increased in a distribution that colocalized in large part with that of TNF-alpha, IL-1 beta, and IL-6. CONCLUSION: The significant levels of baseline and inducible MIF expression in the brain and its regional association with glucocorticoid action underscore the importance of this mediator as a physiological regulator of the inflammatory stress response and further define its role within the neuroendocrine system.

Animals↗
PubMed1997

Insulin secretion is regulated by the glucose-dependent production of islet beta cell macrophage migration inhibitory factor.

Macrophage migration inhibitory factor (MIF), originally identified as a cytokine secreted by T lymphocytes, was found recently to be both a pituitary hormone and a mediator released by immune cells in response to glucocorticoid stimulation. We report here that the insulin-secreting beta cell of the islets of Langerhans expresses MIF and that its production is regulated by glucose in a time- and concentration-dependent manner. MIF and insulin colocalize by immunocytochemistry within the secretory granules of the pancreatic islet beta cells, and once released, MIF appears to regulate insulin release in an autocrine fashion. In perifusion studies performed with isolated rat islets, immunoneutralization of MIF reduced the first and second phase of the glucose-induced insulin secretion response by 39% and 31%, respectively. Conversely, exogenously added recombinant MIF was found to potentiate insulin release. Constitutive expression of MIF antisense RNA in the insulin-secreting INS-1 cell line inhibited MIF protein synthesis and decreased significantly glucose-induced insulin release. MIF is therefore a glucose-dependent, islet cell product that regulates insulin secretion in a positive manner and may play an important role in carbohydrate metabolism.

Animals↗
PubMed1997

The pathogenic role of macrophage migration inhibitory factor in immunologically induced kidney disease in the rat.

Macrophage migration inhibitory factor (MIF) plays a pivotal role in the inflammatory response in endotoxemia and in the delayed-type hypersensitivity response, but its potential as a regulator of immunologically induced disease is unknown. We have addressed this issue by administering a neutralizing anti-MIF antibody in a rat model of immunologically induced crescentic anti-glomerular basement membrane (GBM) glomerulonephritis. Six individual experiments using paired inbred littermates were performed. Rats were primed with rabbit immunoglobulin on day -5 and then injection with rabbit anti-rat GBM serum on day 0. Pairs of animals were treated with anti-MIF or a control monoclonal antibody from the time of anti-GBM serum administration until being killed 14 d later. Control antibody-treated animals developed severe proteinuria and renal function impairment with severe histological damage due to marked leukocytic infiltration and activation within the kidney. In contrast, anti-MIF treatment substantially reduced proteinuria, prevented the loss of renal function, significantly reduced histological damage including glomerular crescent formation, and substantially inhibited renal leukocytic infiltration and activation (all P <0.001 compared with control treatment). Inhibition of renal disease by anti-MIF treatment was attributed to preventing the marked upregulation of interleukin-1beta, leukocyte adhesion molecules including intercellular adhesion molecule-1 and vascular cell adhesion molecule-1, and inducible nitric oxide synthase expression seen in the control antibody-treated animals. This inhibition of progressive renal injury was mirrored by the complete suppression of the skin delayed-type hypersensitivity response to the challenge antigen (rabbit IgG). Interestingly, anti-MIF treatment did not effect the secondary antibody response or immune deposition within the kidney, indicating that MIF participates in cellular-based immunity in this primed macrophage-dependent anti-GBM glomerulonephritis. In conclusion, this study has demonstrated a key regulatory role for MIF in the pathogenesis of immunologically induced kidney disease. These results argue that blocking MIF activity may be of benefit in the treatment of human rapidly progressive glomerulonephritis, and suggest that MIF may be important in immune-mediated disease generally.

Animals↗
PubMed1997

Differential distribution of the mitochondrial heat-shock protein 60 in rat gastrointestinal tract.

Immunohistochemical studies on various parts of the rat gastrointestinal tract by means of an antibody against the mitochondrial chaperonin, heat-shock protein 60 (hsp60), has revealed a cell-specific distribution pattern. The active form of hsp60 is a heptameric complex that is involved in the import and refolding of nuclear-encoded proteins destined for the mitochondrial matrix. This chaperonin is detectable in highly replicating cells, e. g., keratinizing cells of the esophagus and short-living epithelial cells of the intestine. In the stomach, some of the oxyntic cells contain hsp60-positive mitochondria lying near intracellular canaliculi. Neuronal cells of the enteric nervous system present intense positive staining for hsp60 in some areas. All other non-epithelial cells of the digestive tract show weak or no hsp60 immunoreactivity. The presence of hsp60 in mitochondria seems to reflect two different forms of mitochondrial renewal: (1) total reformation of mitochondria and their content after mitotic division and (2) regeneration of these organelles following high activity, e. g., ATP synthesis.

Adenosine Triphosphate↗
PubMed1997

Distribution of heat-shock protein 60 immunoreactivity in testes of infertile men.

The immunohistochemical localization of heat-shock protein 60 (hsp60) was investigated in testicular biopsies obtained from 121 adult men with disturbed fertility. In normal unaffected tubules, hsp60 immunoreactivity was localized to spermatogonia, primary spermatocytes and Sertoli cells. In spermatogonia, cytosolic and mitochondrial labelling could be differentiated. In general, the number of stained spermatogonia decreased with the loss of spermatogenic function. A significant (P<0.01) reduction of stained spermatogonia was observed in testes with maturation arrest of spermatogenesis at the level of primary spermatocytes (30.2+/-21.6%) compared with testes exhibiting normal spermatogenesis. In addition, the decrease in the score correlated significantly with the diminution of cytosolic hsp60 immmunolabelling (coefficient r=0.25, P=0.03). There was a significant difference (P<0.01) in the percentage of cytosolic-stained spermatogonia in testes with a score equal to or greater than 5 (14.7+/-9.8%) and a score less than 5 (8. 9+/-6.9%). These observations suggest that a low level of hsp60 expression in spermatogonia may lead to a different pattern of protection, which in turn could be involved in low spermatogenic efficiency.

Adult↗
PubMed1997

Paracrine regulation of cellular interactions in the testis: factors in search of a function.

Throughout evolution, gamete generation and sex hormone production are the two processes combined in the testis. The local proximity of sex steroid-producing cells and spermatogenic cells allows multiple cellular interactions to occur and thereby facilitates the modulation and/or synchronisation of both testicular functions. This mini review provides an introduction to the vast variety of different testicular cell types, the unique bi-compartmental organization of the testis, the many factors being released in the testis and the different forms of cellular interactions occurring between testicular cells. Selected members of two groups of signal molecules (sex steroids, growth factors) are described in detail and specific examples for the intratesticular actions of signalling factors are presented.

Animals↗
PubMed1997

Migration inhibitory factor expression in experimentally induced endotoxemia.

Macrophage migration inhibitory factor (MIF) is an important constituent of the host response to stress and infection and is the first mediator that has been identified to be released from immune cells upon stimulation with glucocorticoids. MIF also has been shown to be secreted from the anterior pituitary gland, monocytes/macrophages, and T cells activated by various proinflammatory stimuli. Once released, MIF acts to counter-regulate the inhibitory effect of glucocorticoids on inflammatory cytokine production. To characterize more precisely the role of MIF in the host response to infection, we undertook a systematic analysis of MIF expression in various organs of the rat after endotoxin (lipopolysaccharide) administration. MIF protein and mRNA were analyzed by immunohistochemistry and in situ hybridization, respectively. MIF was found to be expressed constitutively in organs such as the lung, liver, kidney, spleen, adrenal gland, and skin. Significant quantities of MIF protein were detected preformed in various cell types and appeared to be released as a consequence of endotoxemia. In virtually all tissues examined, the loss of MIF protein 6 hours after lipopolysaccharide administration was accompanied by the induction of MIF mRNA and, at 24 hours, by the restoration of immunoreactive, intracellular MIF. The constitutive production of MIF by several cell and tissue types together with its rapid release from intracellular pools distinguishes MIF from other cytokines or hormonal mediators and significantly expands the physiological role of this unique counter-regulator of glucocorticoid action.

Adrenal Glands↗
PubMed1996

Transglutaminases: purification and activity assays.

Transglutaminases (TGases) are a widely distributed family of proteins found in many tissues and body fluids of vertebrates. To date the following types have been distinguished: secretory, tissue, epidermal, keratinocyte, and hemocyte TGase as well as factor XIIIa and erythrocyte hand 4.2 TGases are difficult to isolate, as they tend to form irreversible aggregates under native conditions. In this review, the isolation procedures for the different types of TGases are summarized. The most common chromatographic separation methods used for TGase purification are size-exclusion and ion-exchange chromatography. Additionally, other chromatographic methods (hydrophobic-interaction, affinity, adsorption chromatography) and electrophoretic techniques [preparative isoelectric focusing, sodium dodecyl sulphate polyacrylamide gel electrophoresis and zone electrophoresis] are described. Based on the enzymatic function of TGases (cross-linking of a primary amine and peptide bound glutamine), several established activity assays are described.

Animals↗