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.
The enzymic reduction and kinetics of oxidation of cytochrome b-245 of neutrophils. 1. The absorption coefficient of human neutrophil plasma-membrane reduced-minus-oxidized cytochrome b-245 was determined [delta epsilon (mM; 559-540 nm) = 21.6 cm-1]. 2. Neutrophil polymorphonuclear leucocytes (neutrophils) were prepared from human, ox, horse and pig blood. In each case plasma-membrane fractions were found to contain low-potential cytochrome b. When membranes from horse neutrophils were incubated anaerobically with either NADH or NADPH the cytochrome b became reduced. Prior stimulation of the cells with phorbol myristate acetate did not increase the rate or extent of cytochrom...
Energy metabolism of the contagious equine metritis bacterium. The energy metabolism of the English E-CMO strain of contagious equine metritis bacterium was studied in whole cells and cell extracts. This bacterium appears to have an active Krebs cycle and probably obtains energy by oxidative phosphorylation since glycolysis and the hexose monophosphate pathways appear to be absent. These conclusions are based on the findings that [U-14C]glucose incorporation by this bacterium is below the level of detection, and that respiration is stimulated by Krebs cycle intermediates (i.e., malate, citrate, and succinate), but not by glucose, fructose, maltose, or suc...
Resonance-enhanced Raman identification of a ternary chemical intermediate during the equine liver alcohol dehydrogenase reduction of p-(dimethylamino)benzaldehyde. The nature of the binding of aromatic aldehyde and aromatic alcohol substrates to the catalytic zinc of equine liver alcohol dehydrogenase has been studied by using resonance-enhanced Raman spectroscopy. When an excess of both enzyme and coenzyme to substrate is used, a stable ternary chemical intermediate is formed between liver alcohol dehydrogenase and the reduced coenzyme, nicotinamide adenine dinucleotide, and the aldehyde, p-(dimethylamino)benzaldehyde, in the pH range 8.5-0.6. Resonance-enhanced Raman spectra clearly show that this same intermediate is formed between the excess enzyme, ...
The conformational transition of horse heart porphyrin c. The heme iron of horse heart cytochrome c was selectively removed using anhydrous HF. The product, porphyrin c, exhibits the viscosity, far ultraviolet circular dichroic, and fluorescence properties characteristic for native cytochrome c. However, porphyrin c is more susceptible to denaturation by guanidine hydrochloride and by heat than is the parent cytochrome. All of the conformational parameters of porphyrin c exhibit a common reversible transition centered at 0.95 m guanidine hydrochloride at 23 degrees C and pH 7.0. Guanidine denatured porphyrin c refolds in two kinetic phases having tim...
Pancreatic colipase: crystallographic and biochemical aspects. A detailed study of the crystallization of hog and horse colipases has been undertaken. Several crystallographic varieties have been obtained and a 0.3-nm resolution structure determination is actually in progress. The sequence of the A form of horse colipase (one methionine) is given. From spectrophotometric experiments and sequence comparisons, the involvement of the aromatic residue in position 52 in the micelle binding site has been demonstrated.
Selenium status of thoroughbreds in the United Kingdom. The activity of glutathione peroxidase (GSH-Px) was measured in the erythrocytes of 600 Thoroughbred horses in training; the selenium concentrations in whole blood and serum was measured in over 80 of these Thoroughbreds. A quadratic relationship was demonstrated between erythrocyte GSH-Px and whole blood or serum selenium concentration. There was no significant difference in the activity of aspartate aminotransferase, creatine kinase, or gamma-glutamyl transferase in the serum of Thoroughbreds with high erythrocyte GSH-Px activity (more than 25 u/ml) when compared with those with low erythroc...
Biochemical constituents of cerebrospinal fluid in premature and full term foals. Total protein content and a variety of enzyme activities and electrolyte values were determined in 73 cerebrospinal fluid (CSF) samples from 66 horses and ponies. The foals (48) were divided into 3 categories-spontaneously delivered normal foals (Group A), full term induced normal foals (Group B) and premature induced non-surviving foals (Group C). CSF samples from a group of 18 normal adults (Group D) were included for comparison. Paired serum and CSF samples were collected on 32 occasions and subjected to similar analyses. CSF sodium and chloride were always higher than serum sodium and chlo...
Isolation and characterization of beta- and gamma-caseins from horse milk. Three groups of casein components were isolated from horse milk. Group I is almost insoluble at acid and neutral pH, and is rather heterogeneous on alkaline gels with or without sodium dodecyl sulphate. Group II shows strong similarity to beta-casein from other species, as concluded from its amino acid composition and its N- and C-terminal sequences. This group consists of five electrophoretically distinguishable forms, all containing ester phosphate groups but no carbohydrate. Group III is composed of C-terminal fragments of the beta-like (group II) fraction and probably arises from the actio...
[Purification of alpha-1,4 leads to 1,4-glucosyltransferase from horse blood serum]. The purification of alpha-1,4-1,4-glucosyltransferase from the equine serum is presented. Ion-exchange chromatography on DE-11, DE-32 and CM-32 celluloses was applied in the successive steps of isolation. Gel-filtration on Bio-Gel P-200 was the last step of purification; it gave the protein which was homogeneous on disc polyacrylamide gel electrophoresis. The purification degree was of the order 2100 at about 40% yield.
[Properties of alpha-1,4 leads to -glucosyltransferase from the muscles and blood serum of horses]. Alpha-1,4 leads to 1,4-glucosyltransferase preparations from horse muscles and serum were studied. The enzyme proteins from both tissues are very similar. Both proteins have a molecular weight of 240 000 and consist of four subunits of 60 000 daltons each. pH 5,0 is optimal for the activity. Only substrates with alpha-1, 4-linkages can serve as glucosyl donors for transferase reactions. Km values for both enzymes differ very slightly. At low substrate concentrations the hydrolytic activity can be found in addition to transferase reactions. At the concentration of the substrate higher than 40 m...
Isolation and some properties of equine alpha 1-antitrypsin. 1. Equine alpha 1-antitrypsin was isolated from horse plasma by a combination of ammonium sulfate and acidification precipitation followed by ion-exchange chromatography on DEAE-cellulose, molecular sieve chromatography on Sephadex G-200 and affinity chromatography on Cibacron Blue-agarose. 2. The purified protein showed a single precipitin arc on immunoelectrophoresis in agarose but gave two bands on discontinuous polyacrylamide gel electrophoresis (PAGE). 3. Both bands appeared to interact equally with trypsin and were thought to represent two isoinhibitors of equine alpha 1-AT.
Subcellular distribution of particle-associated enzymes in horse neutrophil leukocytes. The subcellular components of purified neutrophil leukocytes from horse blood were fractionated by isopyknic equilibration in sucrose and metrizamide gradients. Five classes of particles have been identified: dense azurophil granules containing the bulk of the lysosomal acid hydrolase and peroxidase activity (A); less dense particles, containing all the lysozyme activity, but not resolved from a second population of azurophils B, and particles of low density, biochemically characterized as a plasma membrane fraction (C). Isopyknic equilibration in sucrose disclosed a minor membrane fraction (D...
Energy metabolism in the erythrocytes of thoroughbred horses connected with perinatal physiological hemolysis. 1. The metabolism in the erythrocytes of thoroughbred horses in a sequential study from umbilical cord to the 1st month was investigated. 2. Emphasis was put on hemolytic period at which: (a). PFK, GSH-Px and GSH play a significant role. (b). There is a lower glucose consumption determined by a decreased activity in several enzymatic steps. (c). Singularly high concentrations of 2-3DPG and ATP were detected. 3. It has been suggested that the metabolic adjustments were achieved by an increased activity of the hexose monophosphate shunt, G-3PD and AK.
The optimum pH of renal adenosine triphosphatase in rats: influence of vanadate, noradrenaline and potassium. In the presence of vanadate, the optimum pH of renal (Na+, K+)-ATPase in rats is reduced and lies in the range of intracellular pH. This explains the difference in optimum pH observed with ATP extracted from equine muscle. Removal of vanadate from such ATP (with noradrenaline) raises the optimum to the accepted range obtained with synthetic ATP. Changes in the sensitivity of the enzyme to potassium concentration contribute to the alterations in optimum pH. The optimum pH of Mg-ATPase is unaffected by vanadate. Since vanadate may be an intracellular regulator of (Na+, K+)-ATPase changes of opti...
Identification of stage-specific and hormonally induced polypeptides in the uterine protein secretions of the mare during the oestrous cycle and pregnancy. Uterine secretions were obtained on Days 4, 8, 12, 14, 16, 18 and 20 of the oestrous cycle and early pregnancy. Acid phosphatase activity was significantly affected by day of the cycle, reaching a maximum at days 12-14 during the luteal phase and then declining to almost undetectable levels, by Day 20. In pregnant animals, activity continued to increase beyond Day 14. Two-dimensional polyacrylamide gel electrophoresis showed that albumin was a major component. However, a number of unique proteins of non-serum origin appeared in mid-cycle but had disappeared by Day 20. One of these was a basic ...
Furosemide, Patella vulgata beta-glucuronidase and drug analysis: conditions for enhancement of the TLC detection of apomorphine, butorphanol, hydromorphone, nalbuphine, oxymorphone and pentazocine in equine urine. We have investigated the action of five sources of beta-glucuronidase enzymes on the hydrolysis of glucuronides of apomorphine, butorphanol, hydromorphone, nalbuphine, oxymorphone and pentazocine in equine urine. For all glucuronides tested, Patella vulgata beta-glucuronidase yielded the largest thin layer chromatographic (TLC) spots. For oxymorphone, P. vulgata was the only treatment to yield detectable TLC spots under test parameters. For these six drugs, TLC spot size and chromatographic quality were compared between control horses and horses pretreated with furosemide four hours earlier. F...
Dehydroepiandrosterone synthesis by the fetal foal and its importance as an oestrogen precursor. The gonads of the fetal horse were found to be relatively devoid of 3 beta-hydroxysteroid dehydrogenase and other enzymes which metabolize dehydroepiandrosterone (DHA). In short-term in-vitro incubation experiments fetal liver converted DHA to the potential equilin precursor, 7 alpha-hydroxy DHA. DHA was converted to oestrone when incubated with extracts of horse placenta but 7 alpha-hydroxy DHA was not converted to equilin. Levels of DHA measured in peripheral blood of mares throughout pregnancy paralleled those of equilin and oestrone, and DHA concentrations fell rapidly after fetal gonadect...
Comparison of the interaction of equine LH and human chorionic gonadotrophin to equine testicular receptors. Human chorionic gonadotrophin (hCG) can be used to study horse luteinizing hormone (LH) receptors in stallion testicular tissue. hCG was more stable than horse LH during radioiodination when compared by their abilities to bind to testicular receptor sites. During incubation, neither hormone lost binding activity at 4 degrees C. Horse LH lost binding activity during incubation at 25 degrees C and both hormones lost binding activity at 37 degrees C. Both hormones bound to the same receptor sites which are specific for the hormones. The receptor sites were not degraded when incubated at 4 degrees...
Titration of antiserum to South American rattlesnake (Crotalus durissus terrificus) venom by measuring inhibition of phospholipase A2 activity. Horse antiserum to the venom of Crotalus durissus terrificus, A South American rattlesnake, inhibits the phospholipase activity of the crude venom. There is a close relationship between this inhibitory property and the neutralizing potency of the antiserum in vivo. This may provide the basis for a rigorous standardization of anticrotalid venom in vitro.
Endotoxin-induced change in hemograms, plasma enzymes, and blood chemical values in anesthetized ponies: effects of flunixin meglumine. A study was made of flunixin meglumine (FM), an analgesic agent with antiprostaglandin activity, in the management of endotoxin-induced changes in ponies. Three groups of 5 ponies each were used: A--controls, B--nontreated ponies with endotoxin-induced shock, and C--ponies with endotoxin-induced shock treated with FM. Shock was induced in anesthetized ponies with IV injections of Escherichia coli endotoxin. Disruption of glucose homeostasis, insulin levels, hemograms, aerobic metabolism, and cell damage as indicated by plasma enzymes were observed. Treatment with FM (5 minutes) after shock was...
Metabolism of purine nucleosides and phosphoribosylpyrophosphate in thymocytes and splenocytes of various mammalian species. 1. Activities of ADA, PNP and AK were measured in splenocytes and thymocytes of newborn children, young horses, pigs, sheep, rats and mice and compared with the activities previously found in peripheral lymphocytes. 2. With all species, except horse, the activity of ADA (per 10(6) cells) was higher in thymocytes than in lymphocytes. Activity of ADA was highest in splenocytes of pig and sheep. Activity of ADA was lowest in all lymphoid cells of the horse and only about 10% of the activity in human splenocytes and lymphocytes. 3. With all species, except horse, the activity of PNP was lower in t...
Cibacron Blue-induced modification of neutral proteinase from horse blood leukocytes. The proteolytic activity of the elastase-like proteinase from granules of horse blood leukocytes is retained on a column of Cibacron Blue-Sepharose and can be eluted with 0.5 M KSCN. During this procedure its mol. wt. is reduced from 49000 to 30000 and isoelectric point is shifted towards higher pH. The inactive protein not adsorbed on Cibacron Blue-Sepharose is strongly acidic and shows a mol. wt. of 20000. Upon mixing this protein with the modified enzyme the native proteinase is reconstituted as shown by polyacrylamide gel electrophoresis at pH 8.3 and isoelectric focusing in a sucrose grad...
Immunodeficiency disease in animals. Significant contributions to understanding the role of lymphocyte subpopulations in the immune response and to the characterization of immunodeficiencies in children have been achieved through study of animal models of immunodeficiency. Additional contributions can be made in two important areas. One is through identification of relevant, naturally-occurring models of adenosine deaminase deficiency and purine nucleoside phosphorylase deficiency. The second, and potentially more important contribution, would be the identification of the metabolic basis for existing immune deficiencies. The nece...
Limited trypsinolysis of porcine and equine colipases. Spectroscopic and kinetic studies. Porcine and equine colipases have been submitted to mild tryptic digestion. Proteolysis occurs at the Arg5-Gly6 bond with the loss of the N-terminal pentapeptide. Studies of native and trypsin-treated colipases by circular dichroism and laser chemically induced dynamic nuclear polarization indicate that proteolysis induces conformational changes in the region of the tyrosine cluster. Experiments in the presence of phospholipid provide further evidence showing that these residues are in or close to the region of the protein interacting with aggregated lipids. Kinetic studies of the reaction of ...
Species specificity of estrogen biosynthesis in pregnancy. Immunochemical difference of placental NADPH-cytochrome c (P-450) reductase in human, baboon and horse. NADPH-cytochrome c (P-450) reductases from human placental aromatase II and from horse placental microsomes were solubilized and purified to show a single band of 83,000 daltons in SDS-polyacrylamide gel electrophoresis. Rabbits were immunized with purified human placental aromatase II NADPHcytochrome c (P-450) reductase. The resulting antibodies (Reduc-Ab) were used to examine the species specificity of estrogen biosynthesis and the reductase activity in humans, baboons, horses and rats. Rcduc-Ab suppressed androstenedione aromatase activity in human, baboon and horse placental microsomes wit...
Effects of aflatoxins in young ponies. Sixteen clinically normal, healthy ponies were randomly assigned to 4 groups and given aflatoxin B1 in doses of 0.045, 0.030, 0.015, and 0 (control) mg/kg of body weight per day for 21 days (or total doses of 0.945, 0.630, 0.315, and 0 mg/kg). The animals were allowed to recover for 3 months and then were reassigned to 4 treatment groups such that each group during the 2nd trial included a pony from each of the groups of the 1st trial. The animals in the new groups were intubated and were given aflatoxin in doses of 0.4, 0.2, 0.1, and 0 (control) mg/kg/day for 5 days ( or total doses of 2.0, 1...
Distribution of 5′-nucleotidase and gamma glutamyl transferase activities in the tissues of the horse. In the horse, 5'-nucleotidase (5'-NT) activity is found mainly in homogenates of lung, kidney, small intestine, mammary gland, liver and pancreas. Lower activities are present in brain and muscle. Activity can be demonstrated histochemically in the glomeruli and tubules of the kidney, in the sinusoidal borders of the hepatocytes and the bile duct epithelium as well as in the blood vessels of all organs. There is no significant difference between the 5'-NT activity in serum and plasma of normal horses and of horses suffering from a range of orthopaedic conditions. Previous findings that gamma g...
Primary structure of 3-phosphoglycerate kinase from horse muscle. I. Purification of cyanogen bromide peptides and amino acid sequence of peptide CB5 (104 residues). 3-Phosphoglycerate kinase was isolated from horse muscle and subjected to the action of cyanogen bromide. The resulting peptides were separated using gel filtration combined with either ion exchange chromatography on phosphocellulose in 6 M urea or high voltage paper electrophoresis. The sequence of the largest peptide, CB5, has been determined by a combination of automated and manual Edman degradation carried out on the intact peptide and derivatives obtained by proteolytic digestion. The isolation of two peptides derived from CB5 by cleavage of the bond between Asp109 and Pro110 facilitated ...