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The fatty acids ( FA) profile was determined in n-3 enriched (Columbus™) Belgian eggs and pork in order to evaluate to what extent the n-3 fatty acids, which are very sensitive to oxidation, are resistant to storage or cooking. In standard eggs or pork, no change of the fatty acid profile was observed after storage or cooking without culinary fat, as well as in Columbus™ eggs and pork after storage. Some cooking processes (eggs in custard and meat in oven) induced a slight significant loss of n-3 fatty acids in Columbus™ eggs or pork (11.1% in fat from eggs cooked in custard vs. 15.3% in raw Columbus™ eggs and 11.0% in fat from oven cooked meat vs. 11.6% in raw Columbus™ meat). As expected, when Columbus™ pork is cooked with culinary fat, its fatty acid profile is modified according to the nature of the fat used. [ABSTRACT FROM AUTHOR]

The titration curves of the histidine residues of porcine lutropin and its isolated α and β subunits have been determined by following the pH-dependence of the imidazole C-2 proton resonances. The isolated α subunit contains a buried histidine, whose C-2 proton does not exchange with solvent, and which has the unusually low pK of 3.3. In the native hormone all the histidine residues have relatively normal pK values (between 5.7 and 6.2). The four histidine C-2 proton resonances have been assigned to specific residues in the amino-acid sequence, by means of deuterium and tritium exchange experiments on the α subunit and its des(92-96) derivative. The histidine with a pK of 3.3 is identified as His-α87. The effects of pH on tyrosine and methyl proton resonances show that the titration of His-87 in the isolated α subunit is accompanied by a significant conformational change which involves loosening of the protein structure but which is not a normal unfolding transition. The role of conformational changes in the generation of biological activity by subunit association in the glycoprotein hormones is discussed. [ABSTRACT FROM AUTHOR]

The amino acid sequence of the porcine β subunit has been established by studies of peptides isolated after tryptic, thermolytic and staphylococcal protease treatments of the reduced and carboxy-methylated chain. The primary structure of the amino-terminal region of the molecule has been solved by automatic sequencing of the reduced and tritium-labeled carboxymethylated subunit. The amino acid sequence of porcine follitopin β subunit differs from that of its human counter- part by several amino acid replacements, deletion or addition of one or several residues. The porcine chain appears shorter at both its amino and carboxy-terminal ends. The chemical evolution of follitropin is briefly considered and compared to these of thyrotropin and lutropin. [ABSTRACT FROM AUTHOR]

The amino acid sequences of both the α and β subunits of porcine thyrotropin have been studied. Bovine thyrotropin primary structure was taken as a model for ordering the tryptic peptides of porcine thyrotropin. The amino acid sequence of the α subunit is identical to that of porcine luteinizing hormone, while oligosaccharide side-chains differ in composition. The primary structure of the β subunit differs from that of bovine thyrotropin by six amino acid replacements, in positions 22, 24, 26, 36, 62 and 69, and by the absence of a methionyl residue at the carboxy terminus. Chemical evolutions of thyrotropin and luteinizing hormone are compared. [ABSTRACT FROM AUTHOR]

The iodination of porcine luteinizing hormone and its subunits, in the presence of lactoperoxidase and hydrogen peroxide has been studied as a function of iodide concentration. The maximum incorporations were 11 iodine atoms per molecule of hormone while it was possible to incorporate up to 10 and 5 iodine atoms per molecule in the isolated α and Β subunits respectively. Both tyrosyl residues of the Β subunit (Β-37 and Β-59), readily iodinated when the subunit, is isolated, are found to be non-reactive in the native hormone. They could thus bc located on poly peptide portions involved in the binding of the subunits. The reactivities of the tyrosines of porcine luteinizing hormone were found to be in the order: α-21 > α-92 ... α93 > α-41 > α-30 ... Β-37 ... Β-59. The susceptibility of peptidic bonds α-20α-21 and α-24-α-25 to trypsin indicates that this part of the molecule, containing Tyr-α-21, is at the surface of the hormone in aqueous solution. Although the Lys-α-95-Ser-α-96 bond is susceptible to trypsin it is not cleaved by carboxypeptidases. Thus, the carboxy-terminal part of the α chain in the native hormone is at the surface of the molecule but its carboxyl end is probably shielded. [ABSTRACT FROM AUTHOR]

Spectrophotometric titrations of porcine and bovine luteinizing hormones and of their subunits have been performed. Despite specific differences in primary structure, similar results were obtained for both hormones as well as for each of their two subunits. While only five out of seven phenolic hydroxyl groups of tyrosyl residues were ionized in the native hormones at alkaline pH, all were titrated in the isolated subunits. From circular dichroism spectra and spectrophotometric titration data it can be assumed that two tyrosyl residues, buried in the native hormones, are exposed to the solvent medium in the isolated subunits. [ABSTRACT FROM AUTHOR]

The primary structure of porcine luteinizing hormone α-subunit was established by determination of the amino acid sequence of its tryptic peptides, which were aligned by homology with the known sequence of ovine luteinizing hormone α-subunit. Its polypeptide chain is shorter by six amino acid residues at its amino-terminus, when compared to the ovine α-subunit. Furthermore four amino acid replacements are observed in the porcine as compared with the ovine chain. Heterogeneity of both carbohydrate prosthetic groups of porcine luteinizing hormone α-subunit is indicated by the different sugar compositions of the glycopeptides isolated in the course of this work. [ABSTRACT FROM AUTHOR]