Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.7 (plasmin)
 9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

More than 100 chromogenic and fluorogenic peptide substrates are now available for the evaluation of coagulation and related parameters. Many of these substrates exhibit undesirable physical properties, such as insolubility, surface adsorption, and interaction with endogenous plasma proteins. Some of these substrates are capable of inhibiting serine protease generation during activation in the global assay. In order to develop synthetic chromogenic substrates with desirable physical and biochemical characteristics, modified amino acids, such as CHG, CHT, and Nleu, have been utilized. Similarly, to provide a favorable molecular environment to facilitate enzyme and synthetic substrate interactions, various molecular manipulations, such as the introduction of bulky groups, is helpful in developing substrates for protein Ca and C1-esterase. Substrates for Factor Xa, CH3-O-CO-CHG-Arg-pNA (bovine Xa, Km 2.5 X 10(-4) M; human, Km 3.5 X 10(-4) M); thrombin, H-D-CHT-Ala-Arg-pNA (bovine thrombin, Km 3 X 10(-6) M; human thrombin, Km 6 X 10(-6) M); plasmin, H-D-Nleu-CHT-Lys-pNA (human plasmin, Km 2.2 X 10(-5) M) were found to have identical or superior biochemical characteristics to the earlier substrates. These newer substrates were found to be more soluble (greater than 5 X 10(-4) M) in physiologic buffer, less susceptible to autoamidolysis at reaction conditions, and did not produce opacity of the test solution in final concentrations of 5 X 10(-4) M. Comparable results on normal and pathologic plasma samples were obtained in various laboratory assays that utilize currently available substrates for Factors Xa and IIa, kallikrein, and plasmin (R = greater than 0.9). We propose that prior to the application of a new synthetic substrate in a given assay, a careful biochemical and physical screening of the substrate, the assay conditions, and the interaction of substrates with plasma proteins is highly desirable.
 ...
PMID:Newer synthetic peptide substrates in coagulation testing: some practical considerations for automated methods. 665 59

Endogenously produced dicarbonyls, such as methylglyoxal (MG), are involved in advanced glycation end-product formation and thus linked to the pathophysiology of diabetic chronic complications. While the search for synthetic new antiglycation agents continues, little attention has been paid to putative antiglycation agents in natural compounds. Given the link between glycation and oxidation, in this work, we study the effects of methylglyoxal on two model systems; plasminogen and antithrombin III (AT III), then we set out to unravel a possible antiglycation effect for extracts of the flavonoid-rich common herbal species Achyrocline satureoides (AS) and Ilex paraguariensis (IP). Using SAR-PRO-ARG-pNA as a specific thrombin substrate, we show that incubation of plasma with MG decreases heparin activation of AT III by up to a 70%, in a dose-dependent manner. A parallel dose-dependent decrease in plasminogen activity reaching more than 50% was shown using D-BUT-CHT-lys-pNA as a plasmin-specific substrate. Extracts of AS and IP display a dose dependent inhibition of the action of the dicarbonyl, already significant at a 1/100 dilution of the herbal infusions. The inhibition was comparable to that obtained by using millimolar concentrations of known AGE inhibitors such as aminoguanidine and carnosine as well as micromolar concentrations of the antioxidant ascorbic acid. We believe our system of whole plasma glycation over 16 h with micromolar concentrations of MG, coupled with the measurement of activities of plasminogen and AT III by specific substrates provides a straightforward, practical method for monitoring the action of putative antiglycation agents. If predictably milder glycated forms of AT III and plasminogen were to be secreted in vivo, the loss of activities shown here could act synergistically to generate hyperthrombicity.
 ...
PMID:The botanical extracts of Achyrocline satureoides and Ilex paraguariensis prevent methylglyoxal-induced inhibition of plasminogen and antithrombin III. 1242 87

Objectives We undertook the present work to device a simple method to study the effects of inhibitors on functional impairment of proteins by the action of glycating agents. Design and methods For that purpose, we first tested the feasibility and optimized the conditions to employ glycation of human plasma coupled with AT III and plasminogen activity measurement, using coagulation test kits available in most clinical laboratories. Results Using D-BUT-CHT-lys-pNA as a plasmin-specific substrate, we show that incubation of plasma with fructose, glyceraldehyde or MG but not glucose decreases plasminogen activity reaching more than 40% in 16 h. A parallel dose-dependent decrease in heparin activation of AT III by up to a 50% was demonstrated using SAR-PRO-ARG-pNA as a specific thrombin substrate. We studied the effects of aminoguanidine, carnosine, quercetin aglycone, alpha tocopherol and ascorbic acid. Conclusion The methods afforded good discrimination between the known different reactivities of glycating sugars as well as the action of known antiglycation agents. They provide a practical system for monitoring the action of putative antiglycation agents.
 ...
PMID:A practical method to study functional impairment of proteins by glycation and effects of inhibitors using current coagulation/fibrinolysis reagent kits. 1263 66