Topic:Peptides
Peptides are short chains of amino acids that are involved in various biological processes in horses. They function as signaling molecules, influencing physiological activities such as metabolism, immune response, and tissue repair. Peptides can be naturally occurring or synthetically derived, and they may serve as therapeutic agents in veterinary medicine. In equine health, peptides are studied for their potential applications in enhancing performance, supporting recovery, and managing conditions like osteoarthritis. This page compiles peer-reviewed research studies and scholarly articles that explore the structure, function, and potential applications of peptides in the context of equine health and disease management.
Equine Cushing’s disease: differential regulation of beta-endorphin processing in tumors of the intermediate pituitary. Equine Cushing's disease is caused by an adenomatous hyperplasia of the intermediate pituitary which secretes high levels of beta-endorphin, ACTH, and other peptide derivatives of POMC. In the present study we found that plasma and cerebrospinal fluid immunoreactive beta-endorphin (i beta-endorphin) levels were 60- and 120-fold higher than control values in horses with Cushing's disease. There were no significant differences in intermediate lobe i beta-endorphin concentrations, although anterior lobe i beta-endorphin was significantly reduced in Cushing's horses, presumably because high levels...
Characterization of the serological cross-reactivity between glycoproteins of the human immunodeficiency virus and equine infectious anaemia virus. The reported serological relatedness between the major glycoproteins of human immunodeficiency virus (HIV gp120) and equine infectious anaemia virus (EIAV gp90) was examined using purified antigens in radioimmunoprecipitation (RIP), radioimmunoassay (RIA) and immunoblot assays with reference serum from acquired immunodeficiency syndrome (AIDS) patients, an anti-gp120 goat serum and EIAV-infected horse serum. To assess the contributions of glycoprotein oligosaccharide and peptide components to any observed reactivities, antigens treated with endoglycosidase F to remove carbohydrate were assayed...
Horse urinary kallikrein, II. Effect of subsite interactions on its catalytic activity. The effect of secondary-subsite interactions on the catalytic efficiency of horse urinary kallikrein was studied using as substrates oligopeptides and peptidyl-4-nitroanilides with L-Arg at P1. The known secondary specificity of tissue kallikreins for hydrophobic residues at P2 was also demonstrated for horse urinary kallikrein and a higher preference of this enzyme for L-Phe over L-Leu at P2 was evident. Interaction of subsites S3 with D-Pro and D-Phe enhanced the catalytic efficiency but tripeptidyl-4-nitroanilides with acetyl-D-Pro, L-Pro and acetyl-L-Pro at P3 were no better substrates tha...
Microanalysis of the amino-acid sequence of monomeric beta-lactoglobulin I from donkey (Equus asinus) milk. The primary structure and its homology with a superfamily of hydrophobic molecule transporters. The complete primary structure of donkey beta-lactoglobulin I was determined by pulsed-liquid phase microsequencing of tryptic peptides. The protein has been isolated in monomeric form and it corresponds to monomeric beta-lactoglobulin of type I. With the inclusion of donkey beta-lactoglobulin I there are 13% common residues amongst the members of the beta-lactoglobulin family. Donkey beta-lactoglobulin I is homologous to the retinol-binding protein, bilin-binding protein and five other proteins belonging to the new superfamily of hydrophobic molecule transporters. A rapid method for peptide i...
Regional distribution and species variation of prolactin binding sites in the brain. The binding of 125I-labeled ovine prolactin (125I-oPRL) to membranes from different brain regions of pigeon, rabbit, rat, pig, calf, horse, and ewe was studied. The hypothalamus from rabbit, pig, horse, and pigeon showed a low but specific binding for 125I-oPRL clearly different from the other brain regions examined (cortex and cerebellum), whereas in the brain from rat, calf, and ewe the binding was very small and quite uniform in the various regions. Also the membranes from choroid plexus of rabbit, pig, calf, and horse showed an evident specific binding for prolactin. The binding of 125I-oP...
The characterization of equine herpes virus-1-infected cell polypeptides recognized by equine lymphocytes. Ponies, without evidence of previous exposure to Equine herpes virus-1 (EHV-1), were experimentally infected with EHV-1 subtype 2 and investigated for lymphocyte transformation to virus-infected cell polypeptides, as shown by separation with gel electrophoresis. Animals made significant responses to Western blot fractions that corresponded to molecular weights of approximately 30,000, 40,000-45,000, 60,000-65,000, 80,000-95,000 and 100,000-140,000 MW. These molecular weight ranges correlated with the positions of major EHV-1 subtype 2 glycoproteins that were found at migration distances approx...
Comparative topography of the immunoreactive alpha-melanocyte-stimulating hormone neuronal systems in the brains of horses and rats. The present study describes and compares the topography of alpha-melanocyte-stimulating hormone (alpha-MSH)-immunoreactive neurons in the forebrain of rats and horses. Two groups of immunoreactive cells were present in both species. These groups were distinguished by their cross-immunoreactivity and topography. The topography of cell bodies with cross-immunoreactivity for peptides derived from pro-opiomelanocortin (POMC) including adrenocorticotropin, 16K, alpha-MSH and beta-endorphin was similar in both species. However, the topography of perikarya which stained only for alpha-MSH, and not fo...
[Isolation and purification of proteolytic enzymes on organo-silica sorbents with immobilized gramicidin S]. Biospecific sorbents for affinity chromatography of proteolytic enzymes have been synthesized by attaching cyclopeptide antibiotic gramicidin S to organo-silica supports. It is shown possible to attach gramicidin S to the organo-silica supports using glutaric aldehyde, p-benzoquinone, soluble and insoluble carbodiimides. The sorbents prepared by these methods were successfully applied for the purification of the crude pepsin from horse gastric juice and proteolytic complex produced by Acremonium chrysogenum.
Site-directed chemical modification of horse cytochrome c results in changes in antigenicity due to local and long-range conformational perturbations. Comparative binding studies with peptide fragments of the whole antigen, or with evolutionarily related intact proteins with varying degrees of sequence homology, have been used extensively to map antigenic sites on proteins to the resolution of single amino acid residues. These methods are limited, however, since high affinity antibodies will often not react with peptides and evolutionarily related proteins are available for only a few antigens. In this study we use site-directed chemical modification of horse cytochrome c to identify residues involved in the binding sites of four monoclonal ...
The role of aromatic side chain residues in micelle binding by pancreatic colipase. Fluorescence studies of the porcine and equine proteins. Fluorescence techniques have been employed to study the interaction of porcine and equine colipase with pure taurodeoxycholate and mixed micelles. Nitrotyrosine-55 of porcine colipase is obtained by modification with tetranitromethane (low excess, in the presence of taurodeoxycholate) of the protein followed by gel filtration and ion-exchange chromatography. Verification of the residue modified was obtained by h.p.l.c. peptide purification and sequence analysis. Reduction and quantitative reaction with dansyl chloride yields a fluorescent derivative that is twice as active in conjunction with ...
Influence of chemotactic agents on the locomotion of equine polymorphonuclear and mononuclear leucocytes. Subpopulations of equine leucocytes, polymorphonuclear and mononuclear cells, were separated from whole blood on a discontinuous Percoll gradient and used in studies of chemokinesis and chemotaxis. Polymorphonuclear cells responded to the chemo-attractant properties of zymosan-activated plasma in Boyden chamber and agarose microdroplet assays but they responded only slightly (Boyden chamber) or not at all (agarose microdroplet) to the peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP). Equine mononuclear cell movement was increased by FMLP in both assay systems and these cells also respond...
Structural studies on equine glycoprotein hormones. Amino acid sequence of equine chorionic gonadotropin beta-subunit. The complete amino acid sequence of the beta-subunit of equine chorionic gonadotropin (eCG beta) has been established by both automated Edman and manual 5-dimethylaminonaphthalene-1-sulfonyl-Edman degradations. Specific fragments were produced by cleavage with Staphylococcus aureus V8 protease, trypsin, or dilute HCl. For the sequence analyses of the heavily glycosylated COOH-terminal portion, a chemical deglycosylation procedure with trifluoromethanesulfonic acid was employed. The peptide chain of eCG beta consists of 149 amino acid residues. Five or more oligosaccharide chains are attached t...
Structural studies on equine glycoprotein hormones. Amino acid sequence of equine lutropin beta-subunit. The amino acid sequence was determined for equine lutropin beta (eLH beta). Large fragments were derived from reduced, carboxymethylated eLH beta by digestion with Staphylococcus aureus V8 protease, by cyanogen bromide cleavage, and by cleavage of acid-labile Asp-Pro bonds. The fragments were purified by gel filtration and high performance liquid chromatography (HPLC). The fragments were sequenced by automated Edman degradation to establish the primary structure of eLH beta. Some peptides were further digested with chymotrypsin and the resulting peptides purified by HPLC. In addition to sequen...
Course and extent of variation of equine infectious anemia virus during parallel persistent infections. Comparisons of peptide and oligonucleotide maps of glycoproteins and RNA from nine isolates of equine infectious anemia virus (EIAV) that were generated during parallel infections of two Shetland ponies revealed that each isolate was structurally unique. Each EIAV isolate contained a unique subset of variant peptides, oligonucleotides, or both, indicating that structural variation in EIAV is a random and noncumulative process and that a large spectrum of possible EIAV variants can be generated in infected animals.
Beta-endorphin: peripheral opioid activity of homologues from six species. The peripheral opioid activity of six homologous beta-endorphins (beta-EPs) were assayed on the guinea pig ileum and the vas deferens of the mouse, the rat and the rabbit. In the guinea pig ileum assay, human beta-EP (beta h-EP) was less potent than camel, turkey, and ostrich beta-EPs, of the same potency as equine beta-EP and more active than des-acetyl salmon beta-EP. In the rat vas deferens, mammalian beta-EPs showed higher activity than those from the bird and the fish, whereas in the mouse vas deferens assay, beta h-EP is more active than those from other species. In the rabbit vas defere...
Acid-stable protease inhibiting polypeptides formed from denatured horse plasma by proteolysis. 1. Trypsin digestion of perchloric acid precipitated horse plasma yielded polypeptides with inhibitory properties for trypsin, chymotrypsin and, to a small extent, kallikrein. 2. The Mr of the inhibitory polypeptides were 73,000 and 24,000. 3. The number, enzyme specificity and Mr of the inhibitory polypeptides differed from the values known for the human being. 4. The inhibitory polypeptides were purified by affinity chromatography on Sepharose-trypsin and by gel filtration through Sephadex G-75. 5. Protease inhibitory polypeptides were generated in the same manner by chymotrypsin, elastase, ...
Shedding and interspecies type sero-reactivity of the envelope glycopolypeptide gp120 of the human immunodeficiency virus. Two glycopolypeptides with molecular weights 160,000 and 120,000 (gp120) are regularly recognized by human immunodeficiency virus (HIV)-specific antisera in lysates of cells persistently infected with HIV. In the present study, gp120 was characterized as the major envelope glycopolypeptide of HIV. Gp120 was identified as the external viral glycoprotein by radiosequencing and by its presence in purified virus. However gp120 was predominantly shed as a soluble protein into the culture fluid. Furthermore gp120 was precipitated by sera from horses infected with equine infectious anaemia virus (EIA...
Equine arteritis virus-induced polypeptide synthesis. Intracellular virus-specific proteins induced by equine arteritis virus (EAV) have been compared with in vitro translation products of virion and intracellular EAV RNAs. In infected BHK-21 cells, the two major virion proteins (C and E1) and polypeptides with mol. wt. of 60,000 (p60), 42,000 (p42) and 30,000 (p30) were found. There were no indications that the viral proteins were processed from a larger precursor as shown by pulse-chase, amino acid analogue and protease inhibitor experiments. The six polyadenylated RNAs that occur in EAV-infected cells were isolated and translated in an mRNA-de...
Isolation and characterization of latherin, a surface-active protein from horse sweat. A protein, latherin, with unusual surface activity was isolated from horse sweat by gel filtration and ion-exchange chromatography. The protein has a Stokes radius, determined by gel filtration, of 2.47 nm, and in the ultracentrifuge sediments as a single species with S20,W 2.05 S, indicating an Mr of 24,400. On SDS/polyacrylamide-gel electrophoresis the molecule behaves as a single peptide chain of apparent Mr 20,000. Latherin contains a high proportion of hydrophobic amino acids (37.2%), and the leucine content (24.5%) is exceptionally high. The unusual composition of the protein may account...
Occurrence and distribution of 5-S-cysteinyl derivatives of dopamine, dopa and dopac in the brains of eight mammalian species. The 5-S-cysteinyl derivatives of dopamine, dopa (3,4-dihydroxyphenylalanine) and dopac (3,4-dihydroxyphenylacetic acid) were synthesized and used as reference compounds in high performance liquid chromatography analyses of extracts from various brain regions of eight mammalian species. All three metabolites were detected in the brains of all the species studied. The regional distribution of the metabolites was similar to that of dopamine; the metabolite concentrations ranged from less than 0.1 percent to more than 1 percent of the dopamine level, the highest ratios generally being found in sub...
Opiate-like and adrenocorticotrophin-like materials in equine pancreas. Equine pancreatic acetone powder was extracted with an acetone-water-HCl mixture. An acid acetone powder resulted by adding a copious volume of acetone to the extract. The powder was subjected to salt fractionation, gel filtration and chromatography on CM-cellulose. Steroidogenic activity, ACTH-like immunoreactivity and opiate receptor binding activity were distributed among the CM-cellulose chromatographic fractions derived from material unretarded as well as from material retarded on Sephadex G-25. The data indicates a separation of steroidogenic and opiate receptor binding activities, and t...
Comparison of specificity of human and horse leucocyte proteinases with synthetic peptide substrates. Highly purified horse leucocyte proteinases 1, 2A and 2B hydrolyze synthetic substrates which are decomposed also by human leucocyte elastase but they are unable to hydrolyze typical substrates of cathepsin G. Thus in distinction to other mammalian species horse leucocytes are devoid of cathepsin G and contain only elastases.
Complexities in the denaturation of horse metmyoglobin by guanidine hydrochloride. The denaturation of horse metmyoglobin by guanidine hydrochloride was studied at pH 6.4 and 25 degrees C. Measurements of both the peptide circular dichroism and the absorbance in the Soret region suggest that the extent of renaturation strongly depends on the time interval during which the protein is exposed to concentrated solutions of the denaturant. From the equilibrium measurements of the absorption in the Soret region, it is concluded that the unfolding of metmyoglobin is complex. This is further supported by kinetic studies of denaturation which suggest the occurrence of the least four ...
Demonstration of a COOH-terminal extension on equine lutropin by means of a common acid-labile bond in equine lutropin and equine chorionic gonadotropin. The beta subunits of equine lutropin and equine chorionic gonadotropin were incubated in 0.013 N HCl for 30 min at 110 degrees C and separated into two fragments by reverse-phase high performance liquid chromatography. The amino acid and carbohydrate compositions of both fragments from each subunit were analyzed. The results demonstrated that equine lutropin-beta has a glycosylated COOH-terminal extension that differs only in carbohydrate composition from the COOH-terminal portion of equine chorionic gonadotropin-beta. This is the first demonstration of a glycosylated COOH-terminal extension i...
The amino-acid sequence of beta-lactoglobulin II from horse colostrum (Equus caballus, Perissodactyla): beta-lactoglobulins are retinol-binding proteins. beta-Lactoglobulin isolated from horse colostrum is heterogeneous and contains two components: beta-lactoglobulin I and beta-lactoglobulin II. These two proteins are monomeric and show differences in their electrophoretic mobilities, chain lengths and primary structures. The complete amino-acid sequence of beta-lactoglobulin II was determined by automated Edman degradation of the intact protein and of the peptides derived from these by digestion with trypsin or chymotrypsin and by chemical cleavage with cyanogen bromide. Unlike other beta-lactoglobulins which contain 162 amino acids, horse bet...
Antigenic determinants of acylphosphatase from porcine skeletal muscle. 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...
The primary structure of monomeric beta-lactoglobulin I from horse colostrum (Equus caballus, Perissodactyla). beta-Lactoglobulin-like proteins were detected in horse colostrum and normal milk using immunological techniques. In contrast to the beta-lactoglobulins sequenced so far these proteins are monomeric and genetically not homogenous. In this paper we report the first primary structure of a monomeric beta-lactoglobulin from horse colostrum. By means of an automatic liquid-phase sequenator the sequence of peptides obtained by tryptic digestion and by cyanogen bromide cleavage was determined. A limited tryptic digestion and hydrolysis with chymotrypsin provided the necessary overlapping peptides. Th...
Partial amino-acid sequence and cysteine reactivities of cytosolic aspartate aminotransferase from horse heart. Cytosolic aspartate aminotransferase (L-aspartate:2-oxoglutarate aminotransferase, EC 2.6.1.1) from horse heart has five cysteine residues, two of which can be titrated with 5,5'-dithiobis(2-nitrobenzoid acid) in the native enzyme with no impairment of catalytic activity. The rate of modification is unaffected by the presence of substrates. Reaction with N-ethylmaleimide leads to loss of catalytic activity, the rate of inactivation being increased by the presence of substrates. Peptides containing 361 amino-acid residues (about 88% of the total number in the protein) have been isolated and ali...