Abstract
A galactose-specific lectin was purified from the skin mucus of African catfish (Clarias gariepinus) and the physicochemical properties determined. Phosphate buffered saline extract of the skin mucus of African catfish specifically agglutinated erythrocytes of rabbit and human blood group B, but did not agglutinate bat, rat, hen and human blood A and O erythrocytes. The haemagglutinating activity of the lectin was completely inhibited by lactose while galactose and melibiose inhibited the activity to some extent and was calcium-independent. The purified lectin has a native and subunit molecular weight of 63, 000 and 20, 000 Daltons, respectively suggesting a homotrimeric structure for the protein. The protein contained 126 amino acid residues per subunit. This was characterized by large amount of polar amino acids that constituted about 60% of the total amino acids. The lectin showed maximum activity over the pH range 6 – 9 and was heat stable up to 50°C. Ethylenediaminetetraacetic acid (EDTA) had no inhibitory effect on its haemagglutinating activity. Periodic acid–Schiff (PAS) staining showed that the lectin was not a glycoprotein. Chemical modifications of serine and arginine residues of the protein did not affect its haemagglutination activity while modifications of cysteine, tryptophan and histidine residues led to total loss of its activity. The study concluded that African catfish skin mucus lectin exhibited similar physicochemical properties with lectins from other fish skin mucus. Key words: African catfish, Lectin, haemagglutination, skin mucus, galactose-specific, Clarias gariepinus
Highlights
Lectins are heterogeneous class of proteins that bind and reversibly to carbohydrates (Lis and Sharon, 1998)
Skin mucus lectins of several species of fish have been shown to bind microorganisms (Tasumi et al, 2002; 2004: Tsutsui et al, 2006, 2007). These findings suggest that lectins contribute to the self-defense mechanism against these microorganisms and support the report that fish skin secretions contain immunoglogulins as well as various innate-defense factors such as complements, C-reactive protein, lysozyme, hemolysin, anti-microbial peptides and lectins (Suzuki et al, 2003; Argayosa et al, 2011; Benhamed et al, 2014)
It was observed that African catfish skin mucus lectin agglutinated only erythrocytes from human blood Group
Summary
Lectins are heterogeneous class of proteins that bind and reversibly to carbohydrates (Lis and Sharon, 1998). Majority of the studies on lectin have been carried out on plant lectins, on the seeds of legume species (Sharon and Lis, 1990; Chrispeels and Raikhel, 1991). They have attracted immense interest because of the various biological activities such as cell agglutination, antiviral, antitumor, antiproliferative, antifungal and immunomodulatory
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
