title: Ultrasensitive fluorogenic substrates for serine proteases.
abstract: Selective, sensitive assays for the quantitation of serine proteases involved in coagulation and fibrinolysis have been developed employing fluorogenic substrates containing a 6-amino-1-naphthalenesulfonamide leaving group (PNS-substrates). Over one hundred substrates were evaluated for hydrolysis by the serine proteases of blood coagulation and fibrinolysis, and substrate structure-efficiency correlations were examined. PNS-substrates which contain Lys in the P1 position are specific for Lys-plasmin and are either not hydrolyzed or hydrolyzed at a relatively low rate by factor Xa, thrombin, or urokinase-type plasminogen activator (uPA). These substrates allow quantitation of Lys-plasmin at concentrations as low as 1 pM. Eighteen of over 90 substrates tested for factor XIa are hydrolyzed by this enzyme at a relatively high rate reaching a k(cat), value of 170 s(-1) and allowing quantitation of factor XIa at 10 fM. Eighteen of almost 90 PNS-substrates tested display high specificity for thrombin, some exceeding that for factor Xa by >10,000-fold and >100-fold for activated protein C (APC). Seven of these substrates have a k(cat) over 100 s(-1) and three of them have a K(M) below 1 microM. They allow the quantitation of thrombin at concentrations as low as 20 fM. For APC, uPA and the factor VIIa/tissue factor complex, quantitation is feasible at 1 pM concentration. For factor Xa and factor VIIa the limits are 0.4 pM and 40 pM respectively. The PNS-substrates presented in this study may be employed for the development of direct and sensitive serine protease assays.
authors.affiliation: Department of Biochemistry, Health Science Complex, University of Vermont, Burlington 05405, USA.
authors.forename: S
authors.initials: S
authors.lastname: Butenas
authors.forename: M E
authors.initials: ME
authors.lastname: DiLorenzo
authors.forename: K G
authors.initials: KG
authors.lastname: Mann
mesh_terms: D000817:Anilino Naphthalenesulfonates / Q000737:chemistry / Q000378:metabolism*; D002863:Chromogenic Compounds / Q000737:chemistry / Q000378:metabolism*; D015945:Factor XIa / Q000378:metabolism; D005341:Fibrinolysin / Q000378:metabolism; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D010446:Peptide Fragments / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012680:Sensitivity and Specificity; D012697:Serine Endopeptidases / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013917:Thrombin / Q000378:metabolism; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism
chemical_list: D000817:Anilino Naphthalenesulfonates; D002863:Chromogenic Compounds; D005456:Fluorescent Dyes; D010446:Peptide Fragments; D011994:Recombinant Proteins; C033809:lys-plasmin; D012697:Serine Endopeptidases; D015945:Factor XIa; D013917:Thrombin; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator