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.
Fujiki Y, Rathnam P, Saxena BB.A tentative amino acid sequence of the beta-subunit of equine follicle-stimulating hormone (FSH) was derived from the sequences of tryptic, thermolytic as well as peptic, subtilisin, and chymotryptic peptides. Equine FSH-beta is analogous to human FSH-beta except six amino acid substitutions at positions 12, 16, 21, 62, 108, and 114. The amino acid sequence suggests that the hormone-specific beta-subunits of FSH are similar at the interspecies level, whereas the amino acid sequences of the hormone nonspecific alpha-subunits show variations.
Rathnam P, Fujiki Y, Landefeld TD, Saxena BB.Six hundred milligrams of follicle-stimulating hormone (FSH), containing 110 NIH-FSH-S1 units/mg, was isolated from 9 kg of equine pituitary glands. The equine FSH was dissociated into alpha- and beta-subunits. A tentative amino acid sequence of the alpha-subunit was determined. The alpha-subunit contained 82 amino acids. The equine FSH-alpha is shorter by 10 to 14 amino acids at the NH2 terminus and has several substitutions at several positions as compared with human FSH-alpha and bovine thyroid-stimulating hormone-alpha. At the intraspecies level, the alpha-subunits of human FSH, human lute...
Braunitzer G, Schrank B, Stangl A, Bauer C.The sequence analysis of llama (Lama glama, Camelidae) hemoglobin is described. The chains were separated, cleaved by trypsin as previously described, quantitatively characterized and sequenced in the sequenator. The llama hemoglobin differs from the human hemoglobin in that it has 25 different amino acids in the alpha chain and 24 different amino acids in the beta chain. The interaction between protein and phosphate is discussed. The earlier finding that the O2 affinity of the llama hemoglobin is dependent on its content of 2, 3-bisphosphoglycerate is interpreted here as a mutation of the 2, ...
Lucke JN, Hall GM.Blood samples were taken from 15 horses before and after a 50-mile ride to examine the changes occurring in some biochemical constituents. There was a significant (P less than 0.05) decrease in plasma potassium, calcium and magnesium concentrations and a rise in inorganic phosphate but there was no alteration in plasma sodium, chloride or protein levels or change in haematocrit. After the ride there was a highly significant (P less than 0.01) fall in blood glucose corresponding with increased lipolysis and a rise in plasma free fatty acids (P less than 0.001) and glycerol (P less than 0.001). ...
Fujita K, Suzuki I, Ochiai J, Shinpo K, Inoue S, Saito H.We found that aloe extract contains a lectin-like substance which reacts with serum proteins of various animals. Furthermore, in human serum 2 proteins, alpha2-macroglobulin and alpha1-antitrypsin, were shown to be reactive with aloe extract.
Joppich-Kuhn R, Luisi PL.The interaction between horse liver alcohol dehydrogenase and the oxidized and reduced forms of the 3-thionicotinamide--adenine dinucleotide coenzyme analogues (sNAD and sNADH) has been investigated by ultraviolet absorption, fluorescence and circular dichroism. The fluorescence of sNADH is enhanced when bound to the enzyme, and the protein fluorescence is quenched by both sNADH (60--65%) and sNAD (65%). The possible origin of the larger quenching produced by sNAD with respect to that of NAD is discussed. Coenzyme dissociation constants have been determined by monitoring the quenching of the p...
Méténier L, Kaminski M.Immunochemical and enzymatic analyses of horse serum carboxylesterase were carried out with respect to the existence of a silent gene. Sera with positive phenotypic expression of esterase, both heterozygotes and presumed homozygotes, were compared with:--sera with positive phenotypic expression but genotypically +/O;--sera with a negative phenotypic expression, i. e. genotypically O/O;--sera of natural +/O "hemi-zygotes": mules (donkey lacking the esterase);--positive sera heated at 60 degrees C;--positive sera after specific inhibition of enzymatic activity. Titration by immunocompetition has...
Papkoff H, Bewley TA, Ramachandran J.Pregnant mare serum gonadotropin and its subunits have been further characterized. Ultracentrifugation of the gonadotropin at pH 1.3 and 11.5 showed little evidence of dissociation compared to pH 8.2. Highly purified subunits are obtained by urea dissociation and ion-exchange chromatography followed by gel-filtration. Circular dichroism spectra of the gonadotropin and its subunits are much like those of ovine lutropin and its subunits in that there is little evidence for secondary structure and one or more tyrosine residues are inaccessible in the intact gonadotropin compared to the subunits. ...
Stefani M, Berti A, Camici G, Manao G, Cappugi G, Ramponi G.Horse muscle acylphosphatase consists of a main chain S-S bound to glutathione. It was found that removal of the glutathione by reduction and successive carboxymethylation of the only cysteine of the main chain affects the stability of the enzyme, mainly with respect to thermal inactivation. On the other hand, the kinetic properties of the enzyme are affected very little.
Reitnour CM.Utilisation of nitrogen was studied in 4 crossbred ponies. A latin square design was used to study the effects of corn gluten meal, casein or urea when added to a low protein basal diet. Apparent nitrogen digestion, nitrogen retention, total plasma protein, plasma urea and plasma-free amino acids were measured. The addition of corn gluten meal, casein or urea to the basal ration increased apparent digestion of nitrogen. Casein produced a significantly greater (P less than 0.05) nitrogen retention than corn gluten meal or urea. Plasma urea nitrogen increased significantly (P less than 0.01) in ...
Gahne B, Juneja RK.Cattle and horse plasma samples of known post-albumin types were radiolabelled with 14C-vitamin D3. These samples were then analysed by polyacrylamide gel electrophoresis, followed by autoradiography. The patterns observed were identical to those of post-albumin variants. The polymorphic post-albumin protein of cattle and horse was thus identified as the vitamin D binding protein and homologous to the Gc protein of human plasma.
Juneja RK, Gahne B, Sandberg K.Horizontal polyacrylamide gel electrophoreses, on 10% separation gel, of horse serum revealed polymorphism of the vitamin D binding protein (Gc protein) and another post-albumin protein (Pa). Family data supported the hypothesis that Gc and Pa types were controlled by autosomal codominant alleles. For both Gc and Pa proteins, the homozygous types showed a single fraction while the heterozygous type had two fractions. Pa types were found to be identical to the post-albumin types reported earlier by starch gel electrophoresis. Two Gc alleles, GcF and GcS, and three Pa alleles, Pa D, Pa F and Pa ...
Jemmerson R, Margoliash E.Of the antigenic determinants so far identified for cytochrome c, only one involves more than a single amino acid substitution between the immunogen and host proteins. Both a threonine at position 89 and a glutamic acid at position 92 control one of the three antigenic sites identified in horse cytochrome c, as expressed in rabbits. Three antibody subpopulations, all directed against this region of the molecule, were isolated from the serum of a single rabbit by adsorption on a series of insolubilized cytochromes c. Antibody fluorescence quenching titrations with a variety of cytochromes c wer...
Ito S, Yamada Y, Hayashi M, Matsubara Y.Somatostatin-, glucagon- and insulin-containing cells in the rat and horse pancreatic islets were investigated by an indirect immunofluorescent technique using antibodies to insulin, glucagon and somatostatin. In the rat pancreatic islets, insulin-containing cells were located centrally, and glucagon and somatostatin or somatostatin-like substance (SLS)-containing cells were peripherally disposed and glucagon-containing cells were situated more peripherally as compared with distribution of somatostatin-containing cells. On the other hand, in the horse pancreatic islets, insulin-containing cell...
Osheroff N, Feinberg BA, Margoliash E, Morrison M.Iodination of horse cytochrome c with the lactoperoxidase-hydrogen peroxide-iodide system results initially in the formation of the monoiodotyrosyl 74 derivative. This singly modified protein was obtained in pure form by ion exchange chromatography and preparative column electrophoresis. It shows an intact 695 nm absorption band, the midpoint potential of the native protein, a nuclear magnetic resonance spectrum which indicates an undisturbed heme crevice structure, a normal reaction with antibodies directed against native horse cytochrome c, and circular dichroic spectra in which the only cha...
Main AR, McKnelly SC, Burgess-Miller SK.A butyrylcholinesterase of mol.wt. approx. 83000 was observed in pooled rabbit serum. The enzyme was named monomeric butyrylcholinesterase to distinguish it from the larger oligomeric butyrylcholinesterase of horse and human serum whose subunits are the same size as the monomeric enzyme. The active-site concentration of monomeric butyrylcholinesterase in the pooled serum was 0.18mum, which is five times the concentration of butyrylcholinesterase in pooled horse serum. This was surprising, since the horse serum is regarded as a rich source of butyrylcholinesterase, whereas rabbit serum is not g...
Jirgensons B, de Haas GH.Conformation of porcine, bovine, and equine pancreatic phospholipases A2 (EC 3.1.1.4) and their zymogens was studied by the circular dichroism (CD) probe in the far and near ultraviolet spectral zones.
All these phospholipases and their zymogens displayed CD curves suggesting the presence of moderate amounts of α-helical conformation. However, on the basis of known primary structure and recent X-ray structural analysis of prophospholipase A2 crystals (Drenth, J., Enzing, C.M., Kalk, K.H. and Vessies, J.C.A. (1976) Nature 264, 373–377), it has to be concluded that the positive CD band cen...
Barstow LE, Young RS, Yakali E, Sharp JJ, O'Brien JC, Berman PW, Harbury HA.Horse heart cytochrome c can be split with cyanogen bromide into a heme peptide (residues 1-65) and a nonheme peptide (residues 66-104). In a process involving (i) complex formation between the two fragments and (ii) restoration of the severed peptide linkage, a fully active cytochrome c preparation can be re-formed. Use has been made of this process to couple the heme peptide to peptide 66-104 synthesized by the Merrifield solid-phase procedure. The semisynthetic product formed in this manner is indistinguishable from reconstituted cytochrome c prepared with nonsynthetic peptide 66-104.
Schochetman G, Fine D, Arthur L, Gilden R, Heberling R.A new retravirus (SMRV) isolated from a squirrel monkey, Saimiri sciureus, has an Mg2+-dependen reverse transcriptase and a buoyant density of 1.17 g/cm3 in sucrose and 1.21 g/cm3 in cesium chloride, similar to the mouse mammary tumor virus and the Mason-Pfizer monkey virus. The polypeptide patter of SMRV as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was distinct from the reported polypeptide patterns of known retraviruses. Four major polypeptides of molecular weights 40,000, 20,000, 14,000 and 8,000 were resolved in virus propagated in human, mink, and canine cell...
Peterman BF, Morton RA.The apparent equilibrium constant and rate of oxidation was investigated for the reaction of cytochrome c with iron hexacyanide. It was found that if horse heart ferricytochrome c was exposed to ferricyanide (to oxidize traces of reduced protein) the cytochrome subsequently, even after extensive dialysis, had an apparent equilibrium constant different from that of electrodialyzed protein. The effect of ferricyanide ion apparently cannot be removed by ordinary dialysis. The ionic strength dependence of the apparent equilibrium constant and bimolecular oxidation rate constant was measured in the...
Seybert DW, Moffat K, Gibson QH, Chang CK.Horse globin has been recombined with 2,4-dimethyldeuteroheme and 2,4-dibromodeuteroheme to yield the corresponding reconstituted hemoglobins, and the ligand binding reactions of these reconstituted hemoglobins have been examined in detail. Both hemoglobins exhibit relatively high n values, but 2,4-dimethyldeuterohemoglobin displays a consistently higher oxygen affinity than native hemoglobin, whereas the oxygen affinity of 2,4-dibromodeuterohemoglobin is consistently lower than that of native hemoglobin. The rate constants l’, and 1’4 for the binding of the first and fourth molecules of C...
Fernley RT.1. Angiotensin I converting enzyme from horse plasma has been extensively purified and shown to be homogeneous by disc-gel electrophoresis. 2. The metal ion involved in the catalytic reaction of the enzyme has been identified for the first time as zinc by atomic absorption spectrometry. 3. A number of other physicochemical properties of the enzyme are described and compared with results obtained by other investigators. The molecular weight was determined by gel filtration to be 113 000 daltons. The pH maximum was found to be 7-4. The chloride activation of the enzyme appears to act by facilita...
Zicker SC, Lonnerdal B.Separation of whey protein from casein in equine milk was achieved by adjustment of pH to 4.3 without addition of calcium, and by ultracentrifugation at 189,000 g for 1 hr. True protein, whey protein, and casein decreased significantly during the first 28 days of lactation with the magnitude of decrease being greatest for whey protein. The proportion of nitrogen in whey protein:casein decreased from 85:15 to 54:46 during the 28 day time period. The concentration of non-protein nitrogen remained relatively constant at 500 mg nitrogen/l but increased in proportion from 2 to 13% of the total nitr...
Ledwozyw A, Jabłonka S, Tusińska E, Herbut M.Factor VIII level in horse, cattle, sheep and pig plasma was estimated by the use of synthetic chromogenic substrate S-2222 (benzoyl-isoleucyl-glutamyl-glycyl-arginyl-p-nitronilide). The highest level of this factor was stated in pig, the lowest one in sheep plasma.
Pirhonen A, Linnala-Kankkunen A, Kenney RM, Mäenpää PH.Protamine P1 amino acid sequences were determined from semen samples of the Przewalski horse, donkey, Somali wild ass, Grevy's zebra, and Grant's zebra (odd-toed perissodactyls), and compared with those of the domestic horse. Although the rate of amino acid variation of protamine P1 is known to be among the most rapidly diverging polypeptides, the equid sequences revealed only little variation. The sequence from the Przewalski horse was identical with that from the domestic horse. The other sequences differed from the corresponding sequences of the domestic and Przewalski horses in two positio...
Dzongowska-Dzongu T, Kotoński B, Hutny J.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...
Sticker LS, Thompson DL, Bunting LD, Fernandez JM.Two diets consisting of bermudagrass hay and a corn-cottonseed hull-based supplement were formulated to provide either 100% (control) or 50% (restricted) of the protein and energy requirements for maintenance for mature mares. Twelve light horse mares were fed the control diet for 7 d, and then at 0800 on d 0, six mares were switched to the restricted diet. All diets were fed as two equally sized meals at 0800 and 1600. At 0800 on d 7, mares receiving the restricted diet were switched back to the control diet. Relative to control mares, mares switched to the restricted diet had reduced plasma ...
Welles EG, Prasse KW, Duncan A, Morris MJ.An antigenic assay was developed for determination of protein C in horses. Protein C, a natural, vitamin K-dependent anticoagulant component in blood, was isolated from equine plasma, a specific antibody was produced in goats, and a rocket electroimmunophoresis assay was established. Tests were performed to verify the identity of the isolated protein C and to determine the purity of the antibody. Protein C antigen was measured in plasma from 34 clinically normal horses, and values were compared with amidolytic function values. The mean (+/- SD) values for the 2 test methods were similar (antig...
Watts EJ, Rose MT.Wounds on the limbs of horses are notoriously difficult to heal, with over production of TGFβ1 thought to be responsible for excessive scarring; in contrast, wounds in the oral cavity heal rapidly with minimal scarring. This experiment aimed to determine the effect of TGFβ1 on the production of mRNA and proteins for various extracellular matrix components by two equine fibroblast cell lines isolated from the oral mucosa and distal limb. Fibronectin mRNA was up-regulated by TGFβ1 in the limb but not the oral cells. TGFβ1 increased the ratio of mRNA for collagen types I-III for the oral cell...
Jollès J, Donda A, Amiguet P, Jollès P.Mare lactotransferrin has been purified and analyzed. Its molecular mass is 81 kDa. A 28 amino acid long N-terminal sequence was established and a first series of comparisons with other transferrins was performed.
Akimenko ZA, Ofitserov VI, Shaprov VV, Iastrebov SI.Homogeneous (according to PAGE) capsid and surface viral proteins were isolated from concentrated purified suspensions of tick-borne encephalitis and Venezuelan equine encephalomyelitis viruses by one-stage reversed-phase HPLC. The amino acid composition and the sequences of their N-terminal parts were determined.
Fujita S, Cleve H.The major glycoproteins of horse and swine erythrocyte membranes were isolated and examined chemically and immunologically. The major glycoprotein of horse erythrocyte membranes had a molecular weight of 33 000 and consisted of 46.2% protein and 53.8% carbohydrate, of which 9.4% was hexose, 10.1% hexosamine and 33.7% sialic acid. This glycoprotein was associated with activity for the infectious mononucleosis heterophile antigen. There were two different major glycoproteins in swine erythrocyte membranes. One major glycoprotein had a molecular weight of 46 200 and consisted of 34.2% protein and...
Reitnour CM.Utilisation of nitrogen was studied in 4 crossbred ponies. A latin square design was used to study the effects of corn gluten meal, casein or urea when added to a low protein basal diet. Apparent nitrogen digestion, nitrogen retention, total plasma protein, plasma urea and plasma-free amino acids were measured. The addition of corn gluten meal, casein or urea to the basal ration increased apparent digestion of nitrogen. Casein produced a significantly greater (P less than 0.05) nitrogen retention than corn gluten meal or urea. Plasma urea nitrogen increased significantly (P less than 0.01) in ...