Topic:Protein
Proteins are essential macromolecules that play diverse roles in the physiology and health of horses. They are composed of amino acids and are involved in various biological processes, including tissue growth, repair, and the synthesis of enzymes and hormones. Dietary proteins are a key component of equine nutrition, influencing muscle development, immune function, and overall performance. Horses require a balanced intake of essential amino acids, which must be obtained through their diet, as they cannot be synthesized endogenously. This page compiles peer-reviewed research studies and scholarly articles that explore the types, functions, and dietary requirements of proteins in horses, as well as their impact on equine health and performance.
beta-Endorphin: isolation, amino acid sequence and synthesis of the hormone from horse pituitary glands. Beta-endorphin has been isolated from equine pituitaries. Its amino acid sequence is identical to that of ovine, bovine and camel beta-endorphins except for substitution of the threonine residue at position 6 by serine. The equine beta-endorphin has also been synthesized by the solid-phase method. In comparison with the human hormone, equine beta-endorphin was shown to possess 3 times the receptor-binding activity in rat membrane preparations and 1.6 times the analgesic potency in the mouse tail-flick assay.
The interaction of equine platelet tropomyosin with skeletal muscle actin. Whereas skeletal muscle tropomyosin binds strongly to muscle F-actin in a buffer containing 30 mM KCl and 1-2 mM free Mg2+, equine platelet tropomyosin only binds stoichiometrically (1 tropomyosin molecule per 6 actin monomers) at higher Mg2+ concentrations (7-8 mM free Mg2+). At low free Mg2+ concentrations (1.5 mM) the binding of the platelet protein is only marginally increased by raising the KCl concentration to an optimal value (0.10-0.20 M). This weaker binding can be attributed to the relatively poor head-to-tail polymerization of platelet tropomyosin and its fewer actin-binding sites. ...
Amino acid sequence of horse colipase B. The complete sequence of the 96 residues composing horse colipase B has been determined by automated analysis of the intact protein, of two CNBr peptides and two tryptic peptides arising, respectively, from the citraconylated chain and from the unreduced protein. The single histidine of the protein is located at position 29 as in horse colipase A. His86, present in the C-terminal region of the pig cofactor and supposed to play a role in the folding molecule, is not conserved in horse B. Large pieces of the pig and horse B chains were found to be identical or very similar, especially the N-term...
Nucleic acid-protein interactions. Degradation of double-stranded RNA by glycosylated ribonucleases. 1. Extensively glycosylated ribonucleases, like the enzymes from pig and horse pancreas, show a much higher activity on double-stranded RNAs than similarly charged, carbohydrate-free RNAases under stranded assay conditions (relatively high salt concentrations). Glycosylated pig and horse pancreas RNAases also show a larger destabilizing effect on double-stranded poly[d(A-T)] X poly[d(A-T)], than that displayed by bovine RNAase A under these conditions. Both activities show a similar dependence on the ionic strength of the medium. 2. A partial enzymic removal of the heterosaccharide side chains...
Crystallization and properties of creatine kinase from equine skeletal muscle. A crystalline creatine kinase was obtained from equine skeletal muscle. The enzyme was homogeneous, as judged by ultracentrifugation and disc electrophoresis on polyacrylamide gel. The crystalline enzyme had a specific activity of 110 units per mg of protein, that is, 14-fold purification over the crude extract of equine skeletal muscle. The molecular weight of the enzyme was determined to be 84,600 by the conventional low-speed sedimentation equilibrium method, and s020,w was 5.32S. Eight cysteine residues were found on amino acid analysis, two of which were essential for the enzymatic activi...
Isolation and characterization of two glycophorins from horse erythrocyte membranes. Crude glycophorin fraction was prepared from horse erythrocyte membranes by extraction with lithium diiodosalicylate and partition in aqueous phenol. Two glycophorins, designated glycophorins HA and HB, were isolated by two different techniques: preparative gel electrophoresis in the presence of sodium dodecyl sulfate and ion-exchange chromatography in the presence of the nonionic detergent Ammonyx LO. Each glycophorin formed at least two bands on gel electrophoresis, which corresponded to a dimeric form and a monomeric form. Glycophorin HA, the major component, had a blocked amino-terminus an...
Stabilization of the C-terminal part of pig and horse colipase by carboxypeptidase and trypsin inhibitors. Pig and horse colipases have been purified by a common procedure using trypsin and carboxypeptidase inhibitors as stabilizers. Two forms of pig colipase were identified: a predominant A1 form with about 103-105 residues, and a minor slightly degraded A2 form in which the last two C-terminal residues, Asp and Ser, were lacking. This type of degradation is considerably slowed down by carboxypeptidase inhibitors. A total of four forms of the horse cofactor were characterized: two (A1 and B1) were probably isocolipases which differed by only a few substitutions. Both contained the same number of r...
Physico-chemical properties of pregnant mare serum gonadotropin. Pregnant mare serum gonadotropin exhibits a dissociation at acid pH as shown by the drop of s20,w values from 3.52 S at pH 8.1 to 2.52 S at pH 2.0. The dissociation is accompanied by an absorbance change with a maximum at 287 nm and a parallel loss of both follicle-stimulating hormone (FSH) and luteinizing hormone (LH) activities as followed by radioreceptor assays. The apparent pKa of the acid transition is 3.45 with an extremely slow and temperature-dependent rate at pH 2.0 (1.8 . 10(-4) s-1 at 37 degrees C). By gel filtration the molecular weight of the active hormone is estimated to be 45 ...
Activation of pigeon erythrocyte adenylate cyclase by cholera toxin. Partial purification of an essential macromolecular factor from horse erythrocyte cytosol. A cytosolic, macromolecular factor required for the cholera toxin-dependent activation of pigeon erythrocyte adenylate cyclase and cholera toxin-dependent ADP-ribosylation of a membrane-bound 43,000 dalton polypeptide has been purified 1100-fold from horse erythrocyte cytosol using organic solvent precipitation and heat treatment. This factor, 13,000 daltons, does not absorb to anionic or cationic exchange resins, is sensitive to trypsin or 10% trichloroacetic acid and is not extractable by diethyl ether. Activation of adenylate cyclase by cholera toxin requires the simultaneous presence of AT...
Rapid-scanning spectral evidence for catalytically nonequivalent but interconvertible forms of equine liver alcohol dehydrogenase. These rapid-scanning stopped-flow kinetic studies of the equine liver alcohol dehydrogenase-catalyzed reduction of p-nitrobenzaldehyde by NADH and (4R)-4-deuterio NADH (NADD) under single turnover conditions establish : (1) The reaction is biphasic using NADD as coenzyme, k1 approximately 200 sec-1, k2 = 0.5 sec-1 and the amplitude ratio (A1)/(A1 + A2) approximately equal to 0.5. (2) Each phase of the reaction involves the oxidation of enzyme-bound reduced coenzyme. (3) The recycling of sites in the presence of 20 mM pyrazole is negligible. (4) The rates of E(NAD-pyrazole) complex formation at...
Fibrinolytic activity without fibrinogenolysis during long-distance racing in horses. Fourteen horses were studied during a 157-km endurance ride. Two humans who ran the 157 km were also evaluated at the finish. Fibrin monomer samples were examined by two-dimensional gel electrophoresis and sodium dodecyl sulfate polyacrylamide gel electrophoresis. Two major species of horse Beta-chain with higher molecular weights and different isoelectric mobilities than human beta-chain were observed. Horse alpha-chains had higher molecular weights than human alpha-chains but similar alpha-chain heterogeneities. Mean euglobulin lysis time (ELT) in the horses was accelerated to similar levels...
Predicted secondary structure of horse muscle acylphosphatase. Comparison with circular dichroism measurements. We have predicted the secondary structure of horse muscle acylphosphatase by the statistical method of Chou and Fasman. In addition, we have studied the circular dichroism spectra of the enzyme, obtaining values for comparison to the predicted results. Discrepancies were found for the alpha-helix content estimated by the two methods.
[Circadian variations in the content of plasma constituants in the brood mare]. Twenty-one circadian blood sample profiles were made in heavy brood mares during pregnancy, lactation or the dry, non-pregnant period. The mares were fed forage-rich diets containing different levels of energy and nitrogen (table 1). Each profile consisted of 7 samples taken at 8 a.m., 11 a.m., 3 p.m., 7 p.m., 11 p.m., 4 a.m. and 8 a.m. The animals were fed at 8:30 a.m. The eleven plasma components evaluated were glucose, non-esterified fatty acids, beta-hydroxybutyrate, acetate, alanine, insulin (energy metabolites), urea, total protein (nitrogen metabolites), calcium, inorganic phosphorus an...
Variations in the properties of equine chorionic gonadotropin. The objectives of this paper are to review the chemical and biological properties of equine chorionic gonadotropin (eCG, PMSG) isolated from the serum. Comparisons are made with eCG isolated from endometrial cups, trophoblast cell culture medium, and low titer serum. The results show that eCG can vary, depending on the source, in both chemical and biological (LH and FSH activity) properties.
Interaction of horse plasma antithrombin III and alpha 1-proteinase inhibitor with some serine proteinases. Antithrombin III and alpha 1-proteinase inhibitor isolated simultaneously from horse citrated plasma were tested for inhibitory activity against bovine trypsin and chymotrypsin, as well as elastase-like neutral proteinases from horse leucocytes. The stoichiometry of reaction and kinetic parameters (kass, Ko) were estimated and related to the protein pattern obtained after exposure of these proteinases to horse inhibitors as analyzed by polyacrylamide gel electrophoresis (PAGE and PAGE-SDS). As shown by fast reaction rates and low values of dissociation constants the two inhibitors effectively ...
[Variations in plasma components in lactating mares at late pregnancy-early lactation (author’s transl)]. In an experiment comparing pregnant then lactating mares with dry non-pregnant mares, the changes in plasma components were studied as indicators of the metabolic utilization of energy (glucose, non-esterified fatty acids, beta-hydroxybutyrate), nitrogen (urea, proteins) or minerals (calcium, phosphorus, magnesium). The mares were fed daily 2 kg concentrate and hay ad libitum. Beta-hydroxybutyrate, magnesium and to a lesser extent glucose were the only constituents whose levels were affected within the period starting one month before and ending one month after foaling. The increase in food in...
Antigen-antibody crossed electrophoretic studies and quantitative comparisons of serum transferrin types in horses. Selected transferrin phenotypes from 14 horses were investigated by antigen-antibody crossed electrophoresis. Horse sera were subjected to starch gel electrophoresis followed by right angle electrophoresis in agarose gels containing rabbit produced anti-horse transferrin. This technique gave an additional zone in the front as compared with 2 transferrin zones seen after ordinary starch gel electrophoresis. Comparisons of transferrin concentrations in horse sera were performed by an immunodiffusion technique. Values were related to a chosen reference serum. A total of 372 horses (210 Norwegian ...
Characterization of the binding of Triton X-100 to equine and rabbit serum albumin. The binding isotherms for Triton X-100 binding to equine and rabbit serum albumin were determined by equilibrium dialysis at 16 degrees C in pH 7.0, I = 0.05 phosphate buffer. Presented in a Scatchard plot, the binding isotherms are a straight line, indicating thermodynamically independent and identical binding sites. In this model equine serum albumin is characterized as having 11 such sites with an equilibrium constant of 6.0 x 10(3) M-1. Similarly, rabbit serum albumin is characterized as having 9 such sites with an equilibrium constant of 8.0 x 10(3) M-1.
In vitro host range of equine infectious anemia virus. Equine infectious anemia virus (EIAV) was successfully inoculated onto cell cultures of canine and feline origin, resulting in chronic infections in these cultures. Infection of equine cell cultures, which were the previous sole in vitro source demonstrated for virus production, was also performed for comparative purposes. Determination of the nature of the virus produced in the heterologous as well as the equine cells was accomplished in several ways. SDS-PAGE of purified virus from the different cell lines indicated very similar protein composition. Immunological identity was observed in gel...
Fractionation and partial characterization of alpha-1-protease isoinhibitors of horse. The principal alpha-1-protease inhibitor of horse was fractionated by classical methods and analysed with a modified fibrinogen-agarose gel electrophoretic method of high sensitivity and resolving power. Starting with an electrophoretically homogeneous inhibitor in unfractionated serum, two isoinhibitor bands became apparent after fractionation with (NH4)2SO4 and DEAE-cellulose DE-52 ion-exchange chromatography. The isoinhibitors differed in electrophoretic migration and in the elution pattern from Sephadex G-100 gel filtration, but possessed identical antigenic determinants and enzyme specifi...
Helix packing and subunit conformation in horse spleen apoferritin. An electron density map of horse spleen apoferritin at 0.28-nm (2.8 A) resolution and its preliminary interpretation have been described previously. Rigorous examination of this and newer maps at the same nominal resolution but calculated from more extensive data sets, including model building in a Richards' comparator, now allows us to report on structural features in more detail. We list inter-helical angles within and between neighbouring subunits, and describe a new short region of inter-subunit anti-parallel pleated sheet. A short section of electron density not properly accounted for in ...
[The immunological relation between human and equine Gc proteins (author’s transl)]. The immunological comparison of human and equine Gc proteins showed partial identical reactions between both species. Immunizations of goats and rabbits with horse serum produced antisera able to recognize human Gc proteins.