Thermodynamic Characteristics of Plasminogen Activation by Indirect Activators

Electrophoresis studies on the contaminating glycosaminoglycans in commercially available hyaluronic acid products

Hyaluronic acid (HA) samples showing inhibition effect on digestion with testicular hyaluronidase (HAase) were found from 16 commercially available HA products, which were supplied from 11 different manufacturers. Most of these HA samples (six samples) were derived from the rooster comb, and one sample was derived from the human umbilical cord. HA oligosaccharides produced by exhaustive digestion of these HA samples with testicular HAases were monitored by capillary electrophoresis, and we found that a few HA samples gave no oligosaccharide products. Detailed analysis of HA samples by cellulose acetate membrane electrophoresis revealed that the HA samples were not digested with HAase because of the presence of a small amount of dermatan sulfate (DS). Analysis of disaccharide units of these HA samples produced by digestion with chondroitinase ABC supported the observations. And the content of DS in the sample was estimated to be ca. 8%. In contrast, these HA samples were easily digested with bacterial hyaluronate lyases from Streptomyces hyalurolyticus and Streptococcus dysgalactiae and gave endproducts of unsaturated disaccharide or unsaturated tetra- or hexasaccharides. The results suggested that the inhibitory effect of DS on HAase is specific to endo-type hydrolase (i.e. testicular HAase). In addition, pharmaceutical preparations of HA derived from rooster comb were easily digested with testicular HAase. These findings will be useful information for clinical or cosmetic use of HA preparations in terms of their half-life.

Induction of catalytic activity of plasminogen by monoclonal antibody IV-Ic in the presence of divalent metal cations and alpha2-antiplasmin

Investigation of the influence of divalent metal cations on the induction of plasminogen catalytic activity by monoclonal antibody IV-Ic showed that the presence of metal cations in the reaction medium changes the induction by slowing down or accelerating the process. Ions of Zn(2+), Mn(2+), and Cu(2+) completely inhibit activation. Ions of Co(2+) and Ni(2+) decrease the rate of the first and second phases of the reaction more than 2 times. Ca(2+) ions do not have any effect on the activation rate. Ions of Mg(2+), Ba(2+), and Sr(2+) increase the rate of the first phase of the reaction by 1.5, 2.0, and 2.0 times and the rate of the second phase by 2.0, 3.8, and 4.7 times, correspondingly. Sr(2+) ions have the strongest stimulating effect on plasminogen activation by monoclonal antibody IV-Ic. Investigation of the dose dependent effect of Sr(2+) on the rate of plasminogen activation by monoclonal antibody IV-Ic showed stimulating effect of Sr(2+) at concentrations from 0.1 to 1.0 mM with half maximum at 0.6 mM. However, Sr(2+) ions do not affect amidolytic activity of plasmin and activation of plasminogen by streptokinase. Sr(2+) ions also do not affect monoclonal antibody IV-Ic binding to plasminogen. The effect of Sr(2+) is specific and mediated by the IV-Ic component. The presence of metal cations affects conformational changes in the process of active site formation. Metal cations also affect structure of the plasminogen molecule active site in the complex with monoclonal antibody IV-Ic and enzyme-substrate interaction. The effect of alpha(2)-antiplasmin on the induction of plasminogen catalytic activity by monoclonal antibody IV-Ic in range of concentrations from 5 to 30 nM has been studied. alpha(2)-Antiplasmin at concentration 30 nM almost completely inhibits induction of plasminogen catalytic activity by monoclonal antibody IV-Ic at the ratio plasminogen/alpha(2)-antiplasmin of 3 : 1. This can be explained by competition of alpha(2)-antiplasmin and monoclonal antibody IV-Ic for the lysine-binding sites of plasminogen and inhibition of the active center in activated complex plasminogen*-mAB IV-Ic. Divalent metal cations and alpha(2)-antiplasmin are important factors in induction of plasminogen catalytic activity by monoclonal antibody IV-Ic.