Submitted to: Poultry Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/20/2014
Publication Date: 6/1/2014
Citation: Packialakshmi, B., Liyanage, R., Rasaputra, K., Lay, J., Rath, N.C. 2014. Isolation and characterization of chicken bile matrix metalloproteinase. Poultry Science. 93(6):1495-1502. Interpretive Summary: We found the chicken bile contains enzymes that break down collagen, a type of protein present in many connective tissues of animals such as muscle and skin. We assumed that these enzymes, called matrix metalloproteinases (MMP), may be involved in normal digestion of raw proteins that may be present in diets of many animals, including birds. We characterized this chicken enzyme using biochemical procedures and identified it as one MMP-2 that can break collagen. Additionally, we found that certain food types particularly the proteins can increase the activities of this enzyme in bile. Our study suggests how some connective tissue proteins may be digested in the intestine of birds without prior denaturation.
Technical Abstract: Avian bile is rich in matrix metalloproteinases (MMP), the enzymes that cleave extracellular matrix (ECM) proteins such as collagens and proteoglycans. Changes in bile MMP expression have been correlated with hepatic and gall bladder pathologies but the significance of their expression in normal, healthy bile is not understood. We hypothesized that the MMP in bile may aid the digestion of native collagens that are resistant to conventional gastric proteases. Hence, the objective of this study was to characterize the bile MMP and check its regulation in association with dietary factors. We used substrate zymography, azocoll protease assay, and gelatin affinity chromatography to detect, and purify MMP from chicken bile. Using zymography and SDS PAGE, 5 bands at 70, 64, 58, 50, and 42 kDa were observed. The bands corresponding to 64, 50 and 42 kDa were identified as MMP2 using trypsin in-gel digestion and matrix assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS) peptide mass fingerprinting. Chickens fed diets containing gelatin supplements showed higher levels of MMP expression in the bile by both azocoll assay and zymography. We conclude that the bile MMP may be associated with the digestion of collagens and other ECM proteins in avian diets.