Purification and characterization of a lectin from the white shrimp Litopenaeus setiferus (Crustacea decapoda) hemolymph.
A 291-kDa lectin (LsL) was purified from the hemolymph of the white shrimp Litopenaeus setiferus by affinity chromatography on glutaraldehyde-fixed stroma from rabbit erythrocytes. LsL is a heterotetramer of two 80-kDa and two 52-kDa subunits, with no covalently-liked carbohydrate, and mainly composed by aspartic and glutamic acids, glycine and alanine, with relatively lower methionine and cysteine contents. Edman degradation indicated that the NH2-terminal of the 80-kDa subunit is composed DASNAQKQHDVNFLL, whereas the NH2-terminal of the 52-kDa subunit is blocked. The peptide mass fingerprint of LsL was predicted from tryptic peptides from each subunit by MALDI-TOF, and revealed that each subunit showed 23 and 22%, respectively, homology with the hemocyanin precursor from Litopenaeus vannamei. Circular dichroism analysis revealed beta sheet and alpha helix contents of 52.7 and 6.1%, respectively. LsL agglutinate at higher titers guinea pig, murine, and rabbit erythrocytes its activity is divalent cation-dependent. N-acetylated sugars, such as GlcNAc, GalNAc, and NeuAc, were the most effective inhibitors of the LsL hemagglutinating activity. Sialylated O-glycosylated proteins, such as bovine submaxillary gland mucin, human IgA, and fetuin, showed stronger inhibitory activity than sialylated N-glycosylated proteins, such as human orosomucoid, IgG, transferrin, and lactoferrin. Desialylation of erythrocytes or inhibitory glycoproteins abolished their capacity to bind LsL, confirming the relevance of sialic acid in LsL-ligand interactions.
Alpuche
Juan
J
Laboratorio de Ecología y Biología Marina Experimental, UMP, Facultad de Ciencias, UNAM. Sisal, Yucatán, C.P. 97130, México.
Pereyra
Ali
A
Agundis
Concepción
C
Rosas
Carlos
C
Pascual
Cristina
C
Slomianny
Marie-Christine
MC
Vázquez
Lorena
L
Zenteno
Edgar
E
D000818:Animals; D002241:Carbohydrates / Q000737:chemistry; D002413:Cations, Divalent / Q000494:pharmacology; D006384:Hemagglutination / Q000187:drug effects; D006458:Hemolymph / Q000737:chemistry / Q000378:metabolism*; D037102:Lectins / Q000737:chemistry* / Q000302:isolation & purification; D033561:Penaeidae / Q000378:metabolism*
D002241:Carbohydrates; D002413:Cations, Divalent; D037102:Lectins