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.
Van den Oord AH, Wesdorp JJ, Van Dam AF, Verheij JA.In commercial samples of equine myoglobin and samples of equine and bovine myoglobin prepared in the laboratory, a small amount of the protein was present as an aggregate. The presence of the myoglobin aggregate could be demonstrated by gel filtration on Sephadex G-100 Superfine, which also provided a means of isolating it. Gel filtration on Sephadex G-100 showed the molecular weights of the equine and bovine moyglobin aggregates to be about 35000 and 34000 respectively, thus supporting the hypothesis that they are dimers. This was confirmed for the equine myoglobin by ultracentrifugation meas...
Simon SR, Cantor CR.The UV circular-dichroism spectra of human and horse hemoglobins have been determined at various degrees of partial saturation with oxygen. Spectra of the two native hemoglobins were compared with spectra of the corresponding proteins modified with a reagent known to eliminate the conformational rearrangement normally associated with cooperativity. Such comparison indicates that one region, around 260 mmu, is sensitive chiefly to the state of the hemes; changes in another region, around 285 mmu, may be correlated with the conformational transformation linked to cooperative interactions. All ci...
Montgomery PC, Dorrington KJ, Rockey JH.Three independent methods have been used
to determine the molecular weights of the heavyand light-polypeptide chain subunits of equine yGab-,
yGc-, and yT-immunoglobulins. Extensively reduced
and alkylated proteins were filtered through standard
columns of Sephadex G-100 or G-200 in 8 M urea405
M propionic acid. Subunit molecular weights were obtained from the linear elution volume, V,, us. logarithm
molecular weight relationship defined for each column
with rabbit yG-globulin heavy and light chains and
horse heart cytochrome c. Molecular weights also were
determined by equilibrium se...
Williams MA, Harrison PM.Horse ferritin was fractionated both by starch-gel electrophoresis and by gel filtration on Sephadex G-200. Monomer fractions contained up to 98% of monomer and oligomer fractions up to 76% of oligomers as determined by quantitative electron microscopy. Percentages obtained from electron micrographs correlated well with analytical starch-gel electrophoretograms and ultracentrifuge patterns. Amino acid analyses of monomer- and oligomer-enriched fractions showed no significant differences. Ferritin oligomers did not apparently dissociate on dilution for electron microscopy or on storage. Apoferr...
Turner GA, Taylor DM.The interactions between tetravalent plutonium and horse serum proteins were studied in vitro by electrophoresis on cellulose acetate and by gel filtration. The results show that in horse serum, as in other mammalian sera, the plutonium is associated principally with the transferrin component of the beta1-globulins. The formation of the plutonium-transferrin complex requires the presence of HCO3-, and plutonium is displaced from the complex by excess iron, thus indicating that similar binding sites may be involved in the complexing of iron and plutonium. The plutonium complex is considered to ...
Babel I, Stella RC, Prado ES.Previous experiments indicated that horse urinary kallikrein (UK) hydrolyzes salminei- e and polyarginine, a but not polylysine. This paper reports the action of UK on bradykinyl-serine, methionyllysyl-bradykinin and lysyllysyl-bradykinin.
Oliver L, Hartree AS.The cystine-containing peptides of horse growth hormone were isolated and their amino acid sequences determined. Four unique half-cystine residues occur in two peptides, one containing 11 and the other, at the C-terminus of the protein, 15 amino acids. These sequences are compared with published data on growth hormones from other species.
O'Callaghan DJ, Hyde JM, Gentry GA, Randall CC.Infection of exponential-phase suspension cultures of mouse fibroblast cells (L-M) with equine abortion virus (EAV) resulted in inhibition of cell growth and marked alterations in host metabolic processes. The synthesis of deoxyribonucleic acid (DNA) and ribonucleic acid was inhibited within 4 hr after infection and was suppressed by more than 90% by the time of maximal virus replication (14 to 18 hr). The overall rate of protein synthesis, however, was similar in uninfected and virus-producing cells as determined by measurements of net protein and isotope incorporation. The time course of vir...
Topper MJ, Prasse KW.To adapt manual human chromogenic assays for coagulation factors VII (F.VII), VIII:coagulant (F.VIII:C), IX (F.IX), and X (F.X), and C1-esterase inhibitor (C1-INH) for use with an automated analyzer, and to measure the activity of these proteins in horses. Methods: 10 healthy horses were used to determine ranges for the assays. Pooled plasma for standards was collected from an additional 20 healthy horses. Methods: A computer-assisted analyzer was programmed from the manual method for commercially available human F.VII, F.VIII:C, F.IX, F.X, and C1-INH chromogenic assay kits. Standards were pre...
Estepa JC, Lopez I, Mayer-Valor R, Rodriguez M, Aguilera-Tejero E.The aim of this study was to evaluate the influence of two commonly used anticoagulants (K3EDTA and lithium heparin) on refractometric and spectrophotometric measurement of total protein (TP) concentration in equine peritoneal fluid samples. The influence of a commercial solution of K3EDTA, a solution of K3EDTA in distilled water and lithium heparin on the refractometric and spectrophotometric (biuret) quantification of TP content in peritoneal fluid samples was assessed. Total protein concentration measured by refractometry was consistently overestimated in samples with commercial K3EDTA. The...
Frape DL.The majority of recent experiments in equine nutrition relates to the metabolism of protein, non-protein nitrogen, carbohydrate, calcium and phosphorus. An understanding of the significance of the nitrogen cycle is emerging in which there is a two-way movement of compounds across the wall of the G.I. tract. Some quantitative estimates of the role of microflora in this process have been made for comparison with similar processes in ruminants. However, the pathway by which the microflora contributes to the nitrogen economy and the extent to which this occurs is not established in the horse. It i...
Rückert C, Kriete M, Jaenicke S, Winkler A, Tauch A.The complete genome sequence of the type strain Corynebacterium uterequi DSM 45634 from an equine urogenital tract specimen comprises 2,419,437 bp and 2,163 protein-coding genes. Candidate virulence factors are homologs of DIP0733, DIP1281, and DIP1621 from Corynebacterium diphtheriae and of sialidase precursors from Trueperella pyogenes and Chlamydia trachomatis.
Matczuk AK, Zhang M, Veit M, Ugorski M.Equine arteritis virus (EAV), an enveloped positive-strand RNA virus, is an important pathogen of horses and the prototype member of the Arteiviridae family. Unlike many other enveloped viruses, which possess homotrimeric spikes, the spike responsible for cellular tropism in Arteriviruses is a heterotrimer composed of 3 glycoproteins: GP2, GP3, and GP4. Together with the hydrophobic protein E they are the minor components of virus particles. We describe the expression of all 3 minor glycoproteins, each equipped with a different tag, from a multi-cassette system in mammalian BHK-21 cells. Copre...
Yamada S, Suruga K, Ogawa M, Hama T, Satoh T, Kawachi R, Nishio T, Oku T.The appearance of NO2- reducing activity of cytochrome c (Cyt c) upon heat denaturation was investigated with equine heart Cyt c. Denatured equine heart Cyt c (dCyt c), which was treated at 100 degrees C for 30 min, had NO2- reducing activity in the presence of dithionite and methylviologen in an aqueous solution under anaerobic conditions. In contrast, hemoglobin and myoglobin had no such activity under the same conditions. Using spectroscopic methods, we found that the appearance of this activity in the Cyt c was due to the following intramolecular changes: unfolding of the peptide chain, ex...
Yee S, Peyton DH.The redistribution of the initially-formed myoglobin heme-insertion isomers from the initially formed 50/50 mixture to the equilibrium ratio of 90/10 has long been assumed to occur by one of two mechanisms, both of which require the rupture of the heme iron-protein bond (La Mar, G.N., Toi, H. and Krishnamoorthi, K. (1984) J. Am. Chem. Soc. 106, 6395-6401). In this study we compared the use of nuclear magnetic resonance and optical spectroscopic techniques as methods for studying the reorientation of heme within myoglobin. We found that kinetics determinations of the heme insertion isomer redis...
Rakotoarisoa L, Mironneau C, Sayet I, Mironneau J.Specific binding of the Ca++ antagonist desmethoxyverapamil, (-)-[3H]D888, to cell membranes of equine portal vein smooth muscle was inhibited in a concentration-dependent manner by guanosine 5'-O-(gamma-thio)triphosphate and ATP but was little affected by guanosine 5'-O-(beta-thio)diphosphate, noradrenaline or phorbol 12-myristate 13-acetate ester. Inhibition constants for GTP and ATP were in the range of 0.1 to 0.3 mM. From Scatchard plots and dissociation kinetic experiments, it is proposed that D888 high affinity binding sites are transferred into low affinity sites. In intact strips of ra...
Hubbard CD, Shoupe TS.A transient phase for the hydrolysis of indophenyl acetate by the commercial preparation of horse serum cholinesterase was observed on a stopped-flow spectrophotometer. It was found that the transient process is a reaction of the ester with a major component of the preparation and is not caused by the serum cholinesterase enzyme. This noncholinesterase component was isolated and the dependence of its concentration and that of the ester upon the transient liberation of the indophenolate ion were determined. Studies with the isolated component and subsequent analyses have led to the tentative id...
Pain R, Sneddon JC, Cochrane CA.Franz diffusion cells containing uniformly dehydrated equine blood clots to simulate fibrinous eschar were used to measure the rate of debridement of fibrin by novel and traditional wound dressings, under standardised conditions of temperature, pH and humidity. Significant increases in protein breakdown occurred within 24 hours with all the dressings, but not thereafter. In general, dressings hydrated in normal saline were better as debriding agents than dressings hydrated in water. Autolytic debriding agents were 47 per cent more effective than chemical debriding agents; specifically, hydrofi...
Greenaway EC, Sepulveda MF, Cunningham FM, Goode NT.Eosinophils have been implicated in the pathogenesis of the seasonal equine allergic skin disease, sweet itch. Protein kinase C (PKC) is involved in regulating eosinophil function and antigen challenge has been reported to alter PKC isotype expression in blood eosinophils from allergic human subjects. Here we have compared the pattern of PKC isotype expression in eosinophils from sweet itch ponies with that in cells from normal ponies both during the active and inactive phases of the disease. A role for PKC in histamine-induced eosinophil activation was also investigated. Conventional PKCs alp...
Kalpokas I, Martínez MN, Cavestany D, Perdigón F, Mattos RC, Meikle A.We investigated the early effects of the equine embryo on maternal serum concentrations of insulin-like growth factor 1 (IGF1), leptin and adiponectin, uterine immune cells and genes and proteins related to embryo development and the maintenance of pregnancy. Ipsilateral endometrial expression was assessed on Days 7 and 13 after ovulation for the following transcripts: oestrogen receptor ERα (ESR1), progesterone receptor (PGR), progestin and adipoQ receptor family member 5 (PAQR5), oxytocin receptor (OXTR), prostaglandin-endoperoxide synthase 2 (PTGS2), raf-1 proto-oncogene serine/threonine k...
Brems DN, Liu YC, Stellwagen E.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...
Stratil A, Tomásek V, Bobák P, Glasnák V.Homozygous horse transferrin (Tf O) is highly heterogeneous. In starch gel electrophoresis it gives at least 9 zones. Two main components (2a and 4b) were purified by rivanol and ammonium sulphate precipitation, DEAE-Sephadex chromatography and SP-Sephadex chromatography. Molecular weights of 75 200 and 80 500 for components 2a and 4b, respectively, were determined by sedimentation equilibrium ultracentrifugation. Amino acid compositions of the two components were similar, and there were no differences in the N-terminus (glutamic acid followed by glutamine) and the C-terminus (valine). Differe...
Williams RC.The evolutionary distance between two sets of proteins was estimated using the techniques of Miyata and Yasunaga (1980) and Kimura (1980). Human beta 2-microglobulin was compared with the homologous murine molecule, while human and equine alpha-globin were similarly treated. It was found that a large amount of molecular evolution has occurred in beta 2-microglobulin since its divergence from the common ancestor of mice and humans. Kimura's estimate of evolutionary distance, K, is 0.353, while those of Miyata and Yasunaga are KS = 0.708 and KA = 0.171. The respective values for human and equine...
Aida Y, Okada K, Kageyama R, Amanuma H.Tumor-associated antigens that are expressed in lymphosarcoma B cells of cattle with enzootic bovine leukosis had been analyzed in terms of their reactivity with 13 monoclonal antibodies (MAB). By use of flow cytometry and radioimmunoprecipitation, 1 of the MAB (c143) that recognized a tumor-associated antigen cross-reacted with blood lymphocytes (BL) from various mammalian species. By use of flow cytometry, the c143 MAB reacted with 10 to 49% of BL derived from human beings, mice, dogs, horses, pigs, llamas, sheep, goats, and cattle. Titer of the c143 MAB with BL from horses, pigs, human bein...
Posthuma CC, Pedersen KW, Lu Z, Joosten RG, Roos N, Zevenhoven-Dobbe JC, Snijder EJ.The replication/transcription complex of the arterivirus equine arteritis virus (EAV) is associated with paired membranes and/or double-membrane vesicles (DMVs) that are thought to originate from the endoplasmic reticulum. Previously, coexpression of two putative transmembrane nonstructural proteins (nsp2 and nsp3) was found to suffice to induce these remarkable membrane structures, which are typical of arterivirus infection. Here, site-directed mutagenesis was used to investigate the role of nsp3 in more detail. Liberation of the hydrophobic N terminus of nsp3, which is normally achieved by c...
Kriegshäuser G, Kuechler E, Skern T.Equine rhinitis A virus (ERAV) is a picornavirus which causes an acute respiratory infection in horses worldwide, and virus neutralization (VN) has been the standard method for the detection of ERAV antibody in horse serum. Previous studies have identified recombinant virion protein VP1 (rVP1) purified under native conditions to be of high potential for the development of a diagnostic ERAV enzyme-linked immunosorbent assay (ELISA). This study presents an optimized protocol for the expression and purification of native full-length rVP1. Furthermore, we demonstrate that, upon denaturation, rVP1 ...
Reitnour CM, Salsbury RL.Protein digestion, nitrogen retention, plasma protein, plasma urea, and plasma-free amino acids were determined for ponies fed 3 different protein supplements. Substitution of casein, corn gluten meal, or corn gluten meal plus lysine for a portion of the cornstarch in a low-protein basal ration increased apparent digestion of protein. Substitution with either casein or corn gluten meal plus lysine produced a significant increase (P less than 0.05) in nitrogen retention, whereas the corn gluten meal substitution did not. Nitrogen retention, expressed as percentage of nitrogen absorbed, was incr...
Dai CB, Xiao Y, Lu H, Shen RX, Shao YM.Membrane protein GP90 of China equine infectious anemia virus (EIAV) vaccine strain (DLV) and its parental wild type LN strain were expressed with Bac-to-Bac baculovirus expression system and BALB/c mice were inoculated with purified protein, thereby to explore the availability of protein for differential diagnosis and potential for preparing genetically engineered vaccine. Methods: The authors infected donkey PBMC culture with China EIAV vaccine strain (DLV) and its parental wild type LN strain, extracted its proviral DNA as template, amplified the GP90 of DLV and LN, respectively, and expres...
Miller PA, Lawrence LM.Six mature Quarter Horse mares were used in a crossover design to assess the effect of dietary protein level on metabolic response to exercise. After a 2-wk adaptation period to either a 12.9% (control) or an 18.5% CP (high-protein) diet, each mare performed a standard exercise test. The test consisted of a 15-min exercise period at 4.5 m/sec on a 9% grade motorized treadmill. Exercise resulted in an increase in heart rate (P less than .001), but there was no difference (P less than .05) between dietary treatments. In the jugular vein, lactate increased (P less than .01) from 6.3 to 52.0 mg/10...
Sticht H, Willbold D, Rösch P.Two molecular dynamics (MD) simulations were performed in order to increase the understanding of the dependence of protein conformation on solvent environment. The protein used for these simulations is the transcriptional activator of the equine infectious anemia virus (EIAV-Tat). The structure of this protein has been determined by nuclear magnetic resonance (NMR) in aqueous solution (Willbold et al., Science 264, 1584 (1994)) and in 40% (v/v) trifluoroethanol (TFE) (Sticht et al., Eur. J. Biochem., submitted) showing considerable differences in the stability of the secondary structure elemen...
Hilbert BJ, Rowley G, Antonas KN, McGill CA, Reynoldson JA, Hawkins CD.Sodium hyaluronate was injected into normal horse joints and joints that had undergone an arthrotomy and experimental cartilage damage. The elimination half-life for hyaluronic acid in normal joints was found to be approximately 96 h. The injection caused a non-significant increase (42%) in synovial fluid protein concentration and a fall in the intrinsic viscosity of the fluid. In the arthrotomy group the synovial fluid hyaluronic acid concentration fell after surgery but it was unaffected by the injection of sodium hyaluronate. An initial rise in the intrinsic viscosity of the synovial fluid ...
Kizaki T, Mizuno Y, Takasawa T, Shiokawa H.Analysis of the quantitative precipitin reaction of acylphosphatase from porcine skeletal muscle with rabbit antiserum indicated the presence of at least two antigenic determinants on the porcine enzyme molecule. Immunological cross-reactivities of acylphosphatases from equine and rabbit skeletal muscles were examined. In double immunodiffusion with the antiserum, the precipitin lines of the porcine and equine enzymes completely fused, while the rabbit enzyme gave no precipitin line. The reaction between the 125I-labeled porcine enzyme and its antibody was inhibited to the same extent by the p...
Kolmakova MV, Kuskova ZR, Ratner GM, Laptakova LM.Horse serum albumin has been shown to meet the requirements to protein preparations for microanalysis and thus to be suitable for use in kits of reagents for the radioimmunological determination of insulin and myoglobin, for the determination of tick-borne encephalitis virus antigen by the method of the enzyme immunoassay and for the stabilization of proteins in the hemagglutination test and the hemagglutination inhibition test.
Word TA, Larsen RW.Here the molar volume and enthalpy changes associated with the early events in the folding of ferrocytochrome c (Cc) at high pH have been examined using time resolved photoacoustic calorimetry (PAC). The data reveal an overall volume change of 1.3 ± 0.3 mL mol and an enthalpy change of 13 ± 7 kcal mol occurring subsequent to photodissociation of the unfolded CO bound Cc species in <∼20 ns. Two additional kinetic phases are observed that are associated with non-native His binding (ΔH and ΔV of 2 ± 4 kcal mol and -0.5 mL mol, τ ∼ 2.5 μs ) and Met binding (ΔH an...
Milne EM, Doxey DL, Gilmour JS.The analysis of peritoneal fluid is of value in the differential diagnosis of equine colic but its characteristics have not been evaluated in grass sickness. Peritoneal fluid was collected from 15 normal horses and from 11 cases of medical colic, 11 cases of surgical colic, 20 cases of acute grass sickness and 13 cases of subacute grass sickness. The fluid was analysed for its appearance, total and differential white cell count, specific gravity, total protein concentration and total and intestinal alkaline phosphatase activity. Fluid from cases of medical colic was normal in these respects. S...
Barbey C, Cauchard S, Cauchard J, Laugier C, Hartke A, Petry S.Rhodococcus equi remains a significant pathogen, causing severe pneumonia in foals. The development of vaccines and serologic diagnosis could be greatly facilitated by studying the humoral immune response to this equine pathogen. In this study, a crude extract of R. equi ATCC 33701-secreted proteins combined with the Montanide® ISA70 adjuvant was found to be highly immunogenic in mice with the highest titer of 99,000 on day 42 after the first subcutaneous immunization. This immune response was dependent on the quantity of proteins injected and the presence of adjuvant. By dot-blotting, eight ...
Ueno Y, Uemura R, Niwa H, Higuchi T, Sekiguchi S, Sasaki Y, Sueyoshi M.Equine proliferative enteropathy (EPE) caused by Lawsonia intracellularis is characterized by hypoproteinemia. There are currently no reliable reports that provide a reference value for the total serum protein (TP) concentration to clinically diagnose EPE. The objective of this study was to statistically determine the reference value. Feces and sera of 99 foals with EPE-like clinical signs and of 35 healthy foals were obtained. The samples were used for specific-gene detection of L. intracellularis, TP measurement, and specific-antibody detection against L. intracellularis. Based on these resu...
Dubin A, Potempa J, Turyna B.Horse blood leucocyte cytosol exhibits a broad inhibitory activity against serine proteinases. The purified inhibitor was exposed to investigated enzymes (trypsin, chymotrypsin, elastases and serine proteinase from S. aureus) for variable time and the products were analyzed by gradient polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. The molar ratio I:E, association rate constants k on and inhibition constants Ki for the enzymes and inhibitor were determined. The examined elastases form stable, stoichiometric complexes with the inhibitor (Ki less than 10(-10) M), ...
