Fig. 7. FXIIIA catalytic activity studies.

Transglutaminase activity of FXIIIA was determined via a coupled spectrophotometric assay, as described under Experimental Procedures. (A) Representative absorbance curves monitoring FXIIIA-mediated ammonia release followed by oxidation of NADH. (i) – FXIIIA fully cleaved by thrombin in the presence of 4 mM CaCl₂; (ii) – same as (i), with addition of 5% DMSO; (iii) – FXIIIA sample with ~50% of the A-subunits cleaved by thrombin in the presence of 4 mM CaCl₂; (iv) – FXIIIA incubated in the presence of 100 mM CaCl₂; (v) – FXIIIA incubated in the presence of 100 mM MgCl₂. (B) transglutaminase activity of FXIIIA is presented by the rate of ammonia-dependent NADH oxidation. Measurements were performed in triplicates for each condition outlined in part A. NADH oxidation rate in the presence of 100 mM MgCl₂ was essentially the same as that in absence of FXIIIA. Values are presented as mean ± SD (n=3).