The kringle is a name given to a sequence of seventy nine residues linked by three disulphide bridges, multiple copies of which have been found in a number of proteins involved in haemostasis. Kringles from plasminogen and prothrombin have been studied using high resolution nuclear magnetic resonance (NMR) spectroscopy. Preliminary experiments demonstrated the kringles to be globular proteins in aqueous solution having well defined tertiary folds. Resonances have been assigned in the NMR spectrum to all but two of the aromatic residues of kringle 4 of human plasminogen and in addition a number of aliphatic residues have also been assigned. The majority of these assignments have been made to specific protons in the protein with the aid of chemically modified kringle 4 derivatives and comparison with other kringle protein spectra. Nuclear Overhauser enhancement studies have demonstrated a number of structurally significant side chain interactions. The lysine binding site of kringle 4 has been explored using two ω-aminocarboxylic acids as ligands. Further structural probes have included copper and lanthanide ions as well as chemically modified kringle 4 species. Combining all the data has allowed a preliminary molecular model to be built of part of kringle 4 incorporating all the residues between the second and third disulphide bridges. Preliminary studies demonstrate the possibility of being able to refine parts of this structure to an accuracy approaching that of X-ray crystallographic studies. A similar number of assignments have been made in the spectrum of bovine prothrombin fragment 2. Comparison of the data on the kringles of both fragment 2 and kringle 4 shows the two proteins to have preserved structural elements, and in particular one of these involves the conserved residues Trp 25, Leu 45 and Trp 61. Furthermore, the two tryptophan residues have been shown to have quite unique spectral charateristics. Brief studies of human prothrombin fragment 2 reveals similar findings. The results discussed indicate that the kringle sequence gives rise to a well defined fold. In kringle 4 of human plasminogen this is seen to provide a highly specific binding site for certain ω-aminocarboxylic acids. The data is all in accord with kringles being autonomous units within the non protease portion of zymogen molecules and which are ideally suited to include the mediation of protein-protein interactions amongst their biological functions.

A genetic approach to lowering protease (plasmin) levels in milk, requires the presence of polymorphism of bovine plasminogen. This study was conducted to determine to what extent genetic polymorphism exists in dairy cattle. Bovine plasminogen was first purified from Holstein cow plasma by affinity chromatography on Lysine-Sepharose and antibodies to bovine plasminogen were raised by monthly intramuscular injection of the isolated bovine plasminogen into rabbits. For plasminogen phenotyping, blood samples were collected at random from 50 Holstein and Ayrshire cattle, and plasminogen was isolated from the plasma using lysine-Sepharose and then treated with neuraminidase. After separation by isoelectric focusing (pH 3.5-9.5) in polyacrylamide gels, Plasminogen polymorphs were detected immunologically using rabbit anti-bovine plasminogen antibodies. Additionally, the plasminogen isoforms were evaluated with a functional assay (caseinolytic overlay technique) after activation of the plasminogen with urokinase. Six plasminogen phenotypes were identified which represent products of 5 variant alleles. The 5 plasminogen variants were characterized based on their isoelectric points and designated PLG A$ sb2$ (pI 6.5 and 7.0), B$ sb2$ (pI 7.6 and 7.8), C$ sb1$ (pI 6.8), D$ sb2$ (pI 7.8 and 8.0), and E$ sb2$ (pI 6.8 and 7.0). PLG A$ sb2$ and PLG B$ sb2$ were the most common variants in these cattle. The 6 phenotypes were $ rm A sb2A sb2, B sb2B sb2, A sb2B sb2, B sb2C sb1, A sb2D sb2 and D sb2E sb2$. The phenotypic frequencies in Holstein and Ayrshire were very different, $ rm A sb2A sb2 and B sb2B sb2$ being respectively the most frequent phenotype. In addition, DNA polymorphism at bovine plasminogen gene was detected when genomic DNA was digested with the restriction enzyme Msp I and hybridized with mouse plasminogen cDNA. This is the first description of plasminogen polymorphism reported in dairy cattle. If different variants have altered activity, the detrimental effect

Diss. (sammanfattning) Göteborg : Göteborgs universitet , 2007. / Härtill 4 uppsatser.

Diss. (sammanfattning) Umeå : Univ., 2004. / Härtill 4 uppsatser.

Thesis (Ph.D.)--University of Wollongong, 2005. / Typescript. Includes bibliographical references: leaf 140-179.

Diss. (sammanfattning) Umeå : Univ., 2007. / Härtill 4 uppsatser.

Thesis (Ph. D.)--Michigan State University. Dept. of Biochemistry, 2007. / Title from PDF t.p. (viewed on Apr. 16, 2009) Includes bibliographical references. Also issued in print.

Thesis (Ph.D.)--University of Alabama at Birmingham, 2009. / Title from first page of PDF file (viewed on June 10, 2009). Includes bibliographical references.

Thesis (doctoral)--Lund University, 1997. / Added t.p. with thesis statement inserted.

Thesis (doctoral)--Lund University, 1997. / Added t.p. with thesis statement inserted.