Dodecamer is required for agglutination of Litopenaeus vannamei hemocyanin with bacterial cells and red blood cells.
Hemocyanins are multi-functional proteins, although they are well known to be respiratory proteins of invertebrate to date. In the present study, the agglutination ability of two oligomers of hemocyanin, hexamer and dodecamer, with pathogenic bacteria and red blood cells (RBCs) is investigated in pacific white shrimp, Litopenaeus vannamei. Hexameric hemocyanin exhibits an extremely high stability even in the absence of Ca(2+) and in alkaline pH. Dodecamer (di-hexamer) is easily dissociated into hexamers in unphysiological conditions. Hexamer and dodecamer are interchanged reciprocally with environmental conditions. Both oligomers can bind to bacteria and RBCs, but agglutination is observed only using dodecamer but not using hexamer in agglutination assay. However, the agglutination is detected when hexamer is utilized in the presence of antiserum against hemocyanin. These results indicate that dodecamer of hemocyanin is required for agglutination with bacteria and RBCs. It can be logically inferred that there is only one carbohydrate-binding site to bacterial cells and RBCs in the hexamer, while at least two sites in the dodecamer. Our finding has provided new insights into structural-functional relationship of hemocyanin.
Center for Proteomics, Department of Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian 361005, People's Republic of China.
Jian-yi
JY
Pan
Yue-ling
YL
Zhang
San-ying
SY
Wang
Xuan-xian
XX
Peng
D000818:Animals; D001419:Bacteria / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D006384:Hemagglutination; D006433:Hemocyanins / Q000378:metabolism*; D008970:Molecular Weight; D033561:Penaeidae / Q000737:chemistry*; D011485:Protein Binding; D013329:Structure-Activity Relationship
D006433:Hemocyanins