Inhibition of the reactivation of acid-dissociated lactate dehydrogenase isoenzymes by their aminoterminal CNBr fragments.

The catalytic activity of lactate dehydrogenase isoenzymes (LDH) depends on their tetrameric structure. Stabilization of this quaternary structure is achieved by interaction of the N-terminal part of one subunit with the C-terminal region of the other subunit. The N-terminal peptides from pig M-LDH and H-LDH which are responsible for this stabilization were obtained by CNBr-fragmentation and purification on reversed-phase HPLC.

Human low-molecular-weight urinary urokinase. Partial characterization and preliminary sequence data of the two polypeptide chains.

Low-molecular-weight urokinase (molecular weight 33100) was separated by analytical and preparative isoelectric focusing into five major subforms with isoelectric points between 8.7 and 9.6.

Comparison of the primary structure of the N-terminal CNBr fragments of human, bovine and porcine plasminogen.

The primary structures of the N-terminal CNBr fragment of human, bovine and porcine plasminogen were determined by automated Edman degradation in a combination of liquid and solid-phase techniques and also by applying the carboxypeptidase method. The comparison of the fragments showed three highly homologous and two variable regions. The heptapeptide sequence responsible for intramolecular interaction is preserved in a conservative region, whereas the sequence of the acidic loop varies considerably between the species.

Peptides isolated from human liver with specific inhibitory effects on reassociation/reactivation of in vitro dissociated lactic dehydrogenase (LDH-M4 and -H4) isozymes.

Two different peptides have been purified from human liver, similar to those previously reported (Schoenenberger, G.A., and Wacker, W.