Omneity® Pellets
All-In-One Vitamin & Mineral Pellet
Topic:Enzymes
Enzymes are biological catalysts that facilitate biochemical reactions in horses by lowering the activation energy required for these processes. They are involved in various physiological functions, including digestion, metabolism, and cellular repair. Common enzymes in equine biology include amylase, lipase, and lactate dehydrogenase, each playing a specific role in the breakdown of nutrients and energy production. The activity and concentration of these enzymes can vary in response to different physiological and pathological conditions, serving as potential indicators in veterinary diagnostics. This page compiles peer-reviewed research studies and scholarly articles that explore the function, regulation, and clinical implications of enzymes in equine health.
Metmyoglobin/azide: the effect of heme-linked ionizations on the rate of complex formation. The kinetics of formation and dissociation of the horse metmyoglobin/azide complex has been investigated between pH 3.5 and 11.5. The ionic strength dependence of the reaction has been determined at integral pH values between 5 and 10. Hydrazoic acid, HN3, binds to metmyoglobin with a rate constant of (3.8 +/- 1.0) x 10(5) M-1 s-1. Protonation of a group with an apparent pKa of 4.0 +/- 0.3 increases the rate of HN3 binding 6.5-fold to (2.5 +/- 0.8) x 10(6) M-1 s-1. The ionizable group is attributed to the distal histidine, His-64. The azide anion, N-3, binds to metmyoglobin with a rate constan...
Immunolocalization of cathepsin B in equine dyschondroplastic articular cartilage. A polyclonal antiserum raised in sheep against human cathepsin B was tested for specificity and cross-reactivity with the horse homologue by SDS-PAGE and Western blotting, prior to being used for immunolocalization of the enzyme in equine articular cartilage. In Western blots, the antiserum recognized the 30 kDa single chain and 25 kDa heavy chain of the mature enzyme in purified bovine cathepsin B, and corresponding bands at 32 and 27 kDa in equine chondrocyte and fibroblast lysates. This antiserum was then used to compare the expression and distribution of cathepsin B in normal and dyschondr...
Equine neutrophil myeloperoxidase in plasma: design of a radio-immunoassay and first results in septic pathologies. The strangulated intestinal pathologies of horses are accompanied by a local activation of the neutrophils, that can be revealed by measuring the tissular enzymatic activity of the granulocytic enzyme myeloperoxidase (MPO). To estimate the possible spreading of this neutrophil activation to the systemic circulation, we designed a radioimmunoassay (RIA) for equine neutrophil myeloperoxidase (MPO) (EC 1.11.1.7) using a specific rabbit antiserum. MPO was labeled with 1 mCi 125I by a technique of self-labeling in the presence of 10(-4) M hydrogen peroxide. The RIA was performed by incubation of 10...
Conformationally restricted carbamate inhibitors of horse serum butyrylcholinesterase. Conformationally restricted carbamate inhibitors, exo-2-norbornyl-N-butylcarbamate (1), endo-2-norbornyl-N-butylcarbamate (2), l-adamantyl-N-butylcarbamate (3), and 2-adamantyl-N-butylcarbamate (4) as active site-directed irreversible inhibitors of horse serum butyrylcholinesterase are investigated for values of the dissociation constant (KI), the carbamylation constant (k2), and the bimolecular rate constant (ki). Compound 1 is the most potent inhibitor of the enzyme and the values of KI and ki are 20 nM and 1.1 x 10(5) M-1sec-1, respectively.
Production of gelatinases and tissue inhibitors of matrix metalloproteinases by equine ovarian stromal cells In vitro. Matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) play very important roles in extracellular matrix (ECM) remodeling in ovarian follicle growth and ovulation. Equine follicles are embedded in cortex that is at the center of the ovary, and they must expand/emigrate to the fossa, the only site in the ovary for ovulation. Therefore, equine ovarian stromal cells (EOSC) are probably involved in ECM remodeling during follicle growth. This study examined whether cultured EOSC synthesize gelatinases and TIMPs, molecules essential for ECM remodeling in other systems. Results showed...
The 2.03 signal as an indicator of dinitrosyl-iron complexes with thiol-containing ligands. The parameters of EPR signal from dinitrosyl-iron complexes (DNIC) with bovine serum albumin (BSA), horse hemoglobin (Hb), and apometallothionein (apo-Mt) of horse kidney incorporating one (BSA, Hb) or two thiol-containing ligands (apo-Mt) were compared. The EPR signal from DNIC-BSA was characterized by the rhombic symmetry of g tensor at room temperature of signal recording (ambient temperature) or at 77K in the solution frozen in the presence of glycerol. In freezing of the solution in the absence of glycerin, under the exposure of DNIC-BSA to negatively charged sodium dodecyl sulfate (SDS) ...
Localisation of gelatinase activity in epidermal hoof lamellae by in situ zymography. In situ gelatin zymography is a technique, which utilises a gelatin-based emulsion overlay to detect and, more importantly, localise the gelatinase activity in underlying tissue. Gelatinase A [matrix metalloproteinase-2 (MMP-2)] and gelatinase B [matrix metalloproteinase-9 (MMP-9)] are present in equine hoof homogenates and supernatants from cultured hoof explants by SDS-PAGE gelatin zymography, and it has been assumed that the enzymes are derived solely from matrix and epithelia and not from other sources such as leucocytes. Using in situ zymography, gelatinases are shown to be localised with...
The effect of drugs commonly used in the treatment of equine articular disorders on the activity of equine matrix metalloproteinase-2 and 9. Loss of articular cartilage, which is the most important pathological lesion occurring in osteoarthritis, has been shown to be enzymatically mediated. The matrix metalloproteinases (MMPs) are a group of enzymes which have been implicated in this degradation of articular cartilage matrix. The use of pharmacological agents to inhibit this catabolic process in the joint is a potential route for therapeutic intervention. The gelatinase MMPs, MMPs-2 and 9, were purified by affinity chromatography from equine cell cultures. The ability of phenylbutazone, flunixin, betamethasone, dexamethasone, methy...
Iron loading into ferritin by an intracellular ferroxidase. An intracellular, membrane-bound enzyme exhibiting both p-phenylenediamine oxidase activity and ferrous iron oxidase activity was isolated with the plasma membrane fraction of horse heart and studied for its ability to load iron into ferritin. The ferroxidase activity of the tissue oxidase was stimulated approximately twofold by horse spleen apoferritin, and the iron was loaded into ferritin. The loading of iron into ferritin by the tissue oxidase was inhibited by anti-horse serum ceruloplasmin antibody. The stoichiometry of iron oxidation and oxygen consumption during iron loading into ferrit...
Pressure and temperature dependence of enantioselective excited-state quenching of chiral Tb(III) and Eu(III) tris(pyridine-2,6-dicarboxylate) chelates by various C-type ferricytochromes. For mitochondrial ferricytochrome c from horse, cow and tuna and for bacterial cytochrome c-550 from Paracoccus versutus, the pressure and temperature dependence of their quenching of racemic Tb(DPA)3(3-) and Eu(DPA)3(3-) (DPA = pyridine-2,6-dicarboxylate) luminescence in aqueous solution is investigated. Of these energy transfer reactions the activation volumes (delta V#) and energies (Ea) are determined for the ranges P = 0-3 kbar and T = 15-40 degrees C. For the lambda enantiomers of Tb(DPA)3(3-) and Eu(DPA)3(3-), delta V# and Ea are almost the same for all proteins: 0.4 < or = delta V# ...
Equilibrium and kinetics of the folding of equine lysozyme studied by circular dichroism spectroscopy. The equilibrium unfolding and the kinetics of unfolding and refolding of equine lysozyme, a Ca2+-binding protein, were studied by means of circular dichroism spectra in the far and near-ultraviolet regions. The transition curves of the guanidine hydrochloride-induced unfolding measured at 230 nm and 292.5 nm, and for the apo and holo forms of the protein have shown that the unfolding is well represented by a three-state mechanism in which the molten globule state is populated as a stable intermediate. The molten globule state of this protein is more stable and more native-like than that of alp...
Equine TIMP-1 and TIMP-2: identification, activity and cellular sources. Matrix metalloproteinases (MMPs) are the main enzymes involved in connective tissue turnover. Regulation of MMPs is achieved by controlling production, activation of the pro-enzymes together with the presence of inhibitors, such as, tissue inhibitors of metalloproteinases (TIMPS). The presence of TIMPs in equine synovial fluid was assessed by the ability of the fluid to inhibit equine MMP-9 activity using a gelatin degradation ELISA. The cellular source of the TIMPs was determined using culture supernatants of resident articular cells (chondrocytes and synovial fibroblasts) and invading inflam...
[Differentiation of domestic horse and Przewalskis horse using various DNA sequences]. The electrophoretic mobility of seven erythrocyte enzymes and spectra of fragments amplified by RAPD-PCR with primers UBC-85 and UBC-126 were comparatively analyzed in domestic horse and Przewalski's horse. All tested genetic markers were classified into two groups differing in their involvement in differentiation of the two closely related horse species. Markers from different groups differed neither in their type (a polymorphic protein or an amplification product) nor in their biochemical role (for enzymes).
[Population genetic parameters of aboriginal Yakut horses as related to modern breeds of the domestic horse Equus caballus L]. This study was the first to analyze the polymorphic characteristics of a wide range of biochemical markers in aboriginal Yakut horses. A total of 124 alleles, including 48 alleles of seven blood-group loci and 76 alleles of ten loci for enzymes and other proteins, were studied. For these polymorphic systems, a computer analysis of the genetic distances between 85 horse breeds of different origin from all parts of the world was performed. The low level of hereditary variation in the Yakut horses confirmed that this breed is old and has long been an isolated population. Phylogenetic analysis dem...
Endocrine and reproductive consequences of certain endotoxin-mediated diseases in farm mammals: a review. After giving an overview of the general pathology of endotoxin-mediated diseases, the authors summarise the endotoxin-induced endocrine changes and their clinical consequences, with particular regard to reproduction. The consequences of temporary activation of the cyclooxygenase-2 and lipoxygenase enzyme systems resulting in elevated release of various prostanoids are discussed in cyclic and pregnant ruminants, sows and mares. The clinical failures attributable to increased glucocorticoid secretion as well as the endotoxin-induced changes in thyroid function and in peripheral level of some oth...
The potential of collagenase as a new therapy for separation of human retained placenta: hydrolytic potency on human, equine and bovine placentae. The purpose of this study was to determine to what degree bacterial collagenase may digest human placentae compared to equine and bovine placentae. Placenta samples from human, equine and bovine were incubated with bacterial collagenase solution at various concentrations. The degree of hydrolysis and collagen breakdown was measured by the release of total proteins and hydroxyproline into the incubation media. Also, whole placentae were injected via umbilical cord arteries with collagenase solution (200 U/ml, 200 ml total volume in human and 1000 ml in equine) and hydrolysis determined chemical...
Triiodothyronine (T3), insulin and characteristics of 5′-monodeiodinase (5′-MD) in mare’s milk from parturition to 21 days post-partum. It is generally accepted that hormones and tissue growth factors are supplied from mother to neonate via mammary secretion. Among the protein hormones, insulin and prolactin are considered as the most important milk components for neonates. The significance of the thyroid hormones, namely triiodothyronine (T3) generated locally by 5'-monodeiodinase (5'-MD) in the mammary tissues, for the mammary gland itself and for suckling neonates is still under consideration. In the present study the activity of the 5'-MD and the concentrations of T3 and insulin in mare's colostrum and milk during the firs...
Characterization of a O-fatty-acylated sulfatide from equine brain. A sulfatide, O-fatty-acylated 3-sulfogalactosylceramide at C6-O on galactoside, was isolated from equine brain and the chemical structure was characterized by proton NMR and MS. The O-acylation site of the acylated sulfatide was determined by the down-field shift of protons attached to a carbon having an O-acyl group in the NMR spectrum and by analysis of a partially methylated derivative before and after acetalization of the intact sulfatide using GC-MS. The O-acyl chain length was determined by GLC, revealing that it exclusively had palmitoyl and stearoyl residues as the major fatty acids. T...
Fusion pore expansion in horse eosinophils is modulated by Ca2+ and protein kinase C via distinct mechanisms. Using the patch-clamp technique, we studied the role of protein phosphorylation and dephosphorylation on the exocytotic fusion of secretory granules with the plasma membrane in horse eosinophils. Phorbol 12-myristate 13-acetate (PMA) had no effect on the amplitude and dynamics of degranulation, indicating that the formation of fusion pores is insensitive to activation of protein kinase C (PKC). Fusion pore expansion, however, was accelerated approximately 2-fold by PMA, and this effect was abolished by staurosporine. Elevating intracellular Ca2+ to 1.5 microM also resulted in a 2-fold accelera...
Inhibition of glutathione S-transferase activity by the quinoid metabolites of equine estrogens. The risk factors for women developing breast and endometrium cancers are all associated with a lifetime of estrogen exposure. Estrogen replacement therapy (ERT) in particular has been correlated with a slight increased cancer risk, although the numerous benefits of ERT may negate this harmful side effect. Equilenin and equilin are equine estrogens which make up between 30% and 45% of the most widely prescribed estrogen replacement formulation, Premarin (Wyeth-Ayerst). In this study we have synthesized the catechol metabolites of equilenin [4-hydroxyequilenin (4-OHEN)] and equilin [4-hydroxyequ...
The activity of mixed function oxidases, estimated by in vivo antipyrine clearance, is similar in horses and camels. The activity of hepatic mixed function oxidases was compared in horses and camels (Camelus dromedarius) by studying the pharmacokinetics of antipyrine in seven camels and five horses following intravenous administration of a single dose of antipyrine (25 mg/kg). The data obtained (mean +/- SEM and median in brackets) in camels and horses, respectively, were as follows: the elimination half-lives were 3.25 +/- 0.23 (3.19) and 3.09 +/- 0.25 (2.90) hr; the apparent volumes of distribution (area method) were 0.691 +/- 0.045 (0.648) and 0.642 +/- 0.034 (0.676) l/kg; the volumes of distribution at s...
Maturation-promoting factor (MPF) and mitogen activated protein kinase (MAPK) expression in relation to oocyte competence for in-vitro maturation in the mare. In the equine species, a large proportion of oocytes fail to complete meiosis during in-vitro culture. The biochemical and molecular basis of this failure is unknown. The meiotic cell cycle is controlled in part by the maturation-promoting factor (MPF) and the mitogen-activated protein kinase (MAPK). In this study, we evaluated the oocyte competence for in-vitro maturation and the expression of MPF components (p34cdc2 and cyclin B) and MAPK after in-vitro culture. The maturation rate was influenced by the culture medium and the physiological stage of the mare at the time of oocyte recovery. We...
Gelatinolytic activity in tracheal epithelial lining fluid and in blood from horses with chronic obstructive pulmonary disease. To determine whether gelatinolytic activity in tracheal epithelial lining fluid (TELF), blood neutrophils, and blood lymphocytes from horses was metalloprotease activity, and to compare, for healthy horses and horses with chronic obstructive pulmonary disease, gelatinolytic activity in neutrophils, lymphocytes, and serum with activity in TELF. Methods: 7 horses with chronic obstructive pulmonary disease (COPD) and 4 healthy control horses. Methods: Neutrophils and lymphocytes were obtained by means of Percoll separation. Zymography was used to detect gelatinolytic activity; EDTA inhibition and...
The interaction of Streptococcus dysgalactiae with plasmin and plasminogen. The activation of plasminogen and the binding of plasmin by bacteria may have many effects which promote infection. The occurrence of such activities in streptococci is well documented; however, these are yet to be demonstrated for S. dysgalactiae. Consequently, the ability of this bacterium to activate mammalian plasminogen and bind either plasmin or its zymogen was investigated. Activation of bovine plasminogen was dependent on both the strain and the growth medium used for cultivation. Eighteen strain were able to activate bovine and ovine plasminogen and some of these also activated plasmi...
Plasma aspartate aminotransferase and creatine kinase activities in thoroughbred racehorses in relation to age, sex, exercise and training. In order to investigate the effect of age, sex and month on the response of plasma aspartate aminotransferase (AST) and creatine kinase (CK) to exercise, blood samples were collected once a month between March and September from a group of 40 2- and 3-year-old (2yo and 3yo) thoroughbred racehorses (kept under the same managemental regimen) at rest before exercise (PRE) and at 2 (2H) and 24 h (24H) post-exercise. The absolute change in activities between the 2H and PRE samples (2H delta) and the 24H and PRE samples (24H delta) was also calculated. Age had a significant effect on all measured an...
Equinins in equine neutrophils: quantification in tracheobronchial secretions as an aid in the diagnosis of chronic pulmonary disease. Equinins are a closely related group of proteins found in equine neutrophil granules. They demonstrate proteinase inhibiting activity restricted to microbial proteinase K and subtilisin, and they also possess antibacterial and antiviral properties. Antiproteinase K activity was measured in tracheobronchial secretions (TBS) of horses with mild (n = 15), moderate (n = 30) and severe (n = 16) chronic pulmonary disease, to determine its usefulness as an indicator of severity of disease and to measure neutrophil content. Determination of proteinase K inhibiting activity was based on a colorimetric ...
Multiple kinetic intermediates accumulate during the unfolding of horse cytochrome c in the oxidized state. The unfolding kinetics of horse cytochrome c in the oxidized state has been studied at 10, 22, and 34 degreesC as a function of guanidine hydrochloride (GdnHCl) concentration. Rapid (millisecond) measurements of far-UV circular dichroism (CD) as well as fluorescence quenching due to tryptophan to heme excitation energy transfer have been used to monitor the unfolding process. At 10 degreesC, the decrease in far-UV CD signal that accompanies unfolding occurs in two phases. The unobservable burst phase is complete within 4 ms, while the slower phase occurs over tens to hundreds of milliseconds. ...
Skeletal muscle glycolytic capacity and phosphofructokinase regulation in horses with polysaccharide storage myopathy. To determine whether polysaccharide storage myopathy (PSSM) in Quarter Horses is attributable to a defect in glycolysis or in the allosteric regulation of phosphofructokinase (PFK) enzyme. Methods: Muscle biopsy specimens were obtained from 6 Quarter Horses with PSSM and 8 Quarter Horse or Thoroughbred control horses. Methods: Maximal activity of glycogenolytic and glycolytic enzymes was determined spectrophotometrically. Maximal activity of PFK was determined for each horse at pH 8.0, and at pH 7.0 when variable concentrations of the activators, fructose 6 phosphate, fructose 2,6 bisphosphate...
Morphologic changes and xanthine oxidase activity in the equine jejunum during low flow ischemia and reperfusion. To determine whether xanthine oxidase and dehydrogenase activities are altered during low flow ischemia and reperfusion of the small intestine of horses. Methods: 5 clinically normal horses without histories of abdominal problems. Methods: With the horse under general anesthesia, a laparotomy was performed and blood flow to a segment of the distal jejunum was reduced to 20% of baseline for 120 minutes and was then reperfused for 120 minutes. Biopsy specimens were obtained before, during, and after ischemia for determination of xanthine oxidase and dehydrogenase activities, and for histologic a...
