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Unconjugated bilirubin inhibits C1 esterase activity.

Clinical biochemistry (2009-01-20)
Sandra M Arriaga, Cecilia L Basiglio, Aldo D Mottino, Adriana M Almará
ABSTRACT

To evaluate if unconjugated bilirubin (UB) inhibits C1 esterase activity. Esterase activity was evaluated by C1-mediated hydrolysis of N-acetyl-L-tyrosine ethyl ester, and binding of UB to C1r and C1s was assessed by dot-blot analysis. UB inhibited C1 enzymatic activity. C1r, C1s and human serum albumin bound [(14)C]-UB to a similar extent. UB inhibits C1 esterase activity, apparently due to a direct pigment-protein interaction. This could explain the inhibitory action of UB on complement activation.

MATERIALS
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Brand
Product Description

Sigma-Aldrich
N-Acetyl-L-tyrosine ethyl ester monohydrate