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Biomedical subjects

B N Violand

Publications and source records attributed to B N Violand.

24 records · Page 2Linked to original sources
PubMed1977

Isolation and characterization of native and lower molecular weight forms of sheep plasminogen.

Two major forms of native sheep plasminogen (SPg-a) have been isolated from plasma by affinity chromatography. These forms differ in molecular weight, charge characteristics, affinity for epsilon-aminocaproic acid (epsilon-Ahx), and carbohydrate content. Upon treatment of SPg-a with plasmin, lower molecular weight plasminogens can be isolated. A plasminogen (SPg-b) of molecular weight approximately 8,000 less than native plasminogen is rapidly produced when either major plasminogen form is treated with plasmin. The molecular weight differences found in the major SPg-a forms are retained in the SPg-b forms, derived from each SPg-a. Upon protracted treatment of either major form of SPg-a or SPg-b with plasmin, a plasminogen (SPg-c) or molecular weight approximately 32,000 less than SPg-b is produced. A single peptide (P) is also produced in this step. The SPg-c species produced from each original SPg-a major form possess essentially the same molecular weights and carbohydrate compositions; but the P cleaved retains the molecular weight and carbohydrate differences found in each major SPg-a or SPg-b form. A large decrease in the S20,w of SPg-a is observed upon the binding of epsilon-Ahx to this protein. A much smaller alteration in the S20,w of SPg-b and SPg-c is observed upon binding of epsilon-Ahx to these proteins.

Amino Acids↗
PubMed1977

Purification and some properties of the Glu- and Lys-human plasmin heavy chains.

The heavy polypeptide chains of human Glu-plasmin and human Lys-plasmin have been isolated in native solvents, after partial reduction and carboxymethylation of the corresponding plasmins. Two major forms of each heavy chain can be eluted, after adsorption to Sepharose/lysine, utilizing a gradient of epsilon-aminocaproic acid as the eluant. The elution profile of these heavy chains is practically identical to the elution behavior previously observed for human Glu- and Lys-plasminogen, and human Glu- and Lys-plasmin adsorbed to these columns. Sedimentation velocity analysis of the heavy chain of human Glu-plasmin, in the presence of epsilon-aminocaproic acid, demonstrated that a gross conformational alteration occurs in this peptide accompanying binding of this amino acid. A much smaller conformational alteration occurs under similar circumstances with the human Lys-plasmin heavy chain. We find that the NH2-terminal peptide released in the Glu-plasminogen to Lys-plasminogen and Glu-plasmin to Lys-plasmin conversions is also released in the Glu-plasmin heavy chain to Lys-plasmin heavy chain conversion. This reaction is catalyzed at a significant rate only by plasmin and not by urokinase. Finally, no strong interaction between streptokinase and the isolated plasmin heavy chains is observed.

Fibrinolysin↗
PubMed1976

Mechanism of the urokinase-catalyzed activation of human plasminogen.

When human plasminogen (Glu-Pga) is activated by urokinase in the presence of pancreatic trypsin inhibitor, the plasmin produced (Glu-Pma) exclusively contains a heavy chain (Glu-Ha) derived intact from the original NH2 terminus of Glu-Pga. Similar activations, utilizing a low molecular weight synthetic plasmin acylating agent, p-nitrophenyl-p-(pyridiniummethyl) benzoate, still result in a plasmin molecule with approximately 50% of the plasmin heavy chain containing the intact NH2 terminus of the original Glu-Pga. Activations performed at high levels of urokinase in the absence of any inhibitors initially produce Glu-Pma. However, the final stable plasmin, Lys-Pmb, which is obtained contains a heavy chain (Lys-Hb) which arises by plasminolysis of a small peptide from the NH2 terminus of Glu-Ha. Alternatively, Lys-Pmb can be formed in a separate series of reactions initially involving plasminolysis of Glu-Pga to yield Lys-Pgb. The peptide removed in this step is identical to the peptide removed in the Glu-Ha to Lys-Hb reaction. Next, urokinase catalyzes the conversion of Lys-Pgb to Lys-Pmb without further loss of peptide material. This latter pathway involving Lys-Pgb is probably the major pathway for human Lys-Pmb generation. These studies support a mechanism of activation of human plasminogen which involves at least two bond cleavages in Glu-Pga. However, these same studies strongly indicate that the Nh2-terminal peptide need not be released from Glu-Pga prior to plasmin formation. Further, we feel that plasmin and not urokinase catalyzes cleavage of the NH2-terminal peptide bond from Glu-Pga and the Glu-Ha heavy chain of Glu-Pma.

Endopeptidases↗