Effects of Denaturation and Amino Acid Modification on Fluorescence Spectrum and Hemagglutinating Activity of Hericium erinaceum Lectin

Meng GONG, Jie AN,
Hong-Zhou Lü, Chuan-Fang WU, Yi-Jin LI,
Jing-Qiu CHENG, and Jin-Ku BAO*
( College of Life Sciences, Sichuan University, Chengdu 610064, China )

Abstract A sialic acid-binding
lectin (Hericium erinaceum lectin, HEL), isolated from fresh fruiting
bodies of Hericium erinaceum, was treated with various temperature and
pH to investigate its fluorescence spectra and hemagglutinating activity. It
was found that the hemagglutinating activity of HEL was relatively
steady below 60 °C and at pH from 6 to 11, and the change of hemagglutinating
activity was relative to the change of hydrophobic areas where tryptophan residues
located. In fluorescence quenching study of HEL by acrylamide and KI, it was
indicated that nearly all the tryptophan residues of HEL located on the surface
of
the molecule, and most of them were in hydrophobic areas or negatively charged
areas. Chemical modification of HEL proved that there were about twelve tryptophan
residues in a HEL molecule and all of them were located on the surface or in
the shallow groove of the molecule, and eight of them were essential for hemagglutinating
activity; aspartic acid or glutamic acid residues were involved in maintaining
the crucial conformation of activity center and made great contribution to the
hemagglutinating activity of HEL, but they could not touch the sialic acid molecule
directly; tyrosine residues also played a role in the hemagglutinating activity
of HEL; while arginine, serine, threonine, histidine residues had no effect
on the hemagglutinating activity of HEL.

Key words sialic acid-binding
lectin; Hericium erinaceum lectin; fluorescence spectrum and fluorescence
quenching; hemagglutinating activity; chemical modification

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Received: February, 16, 2004 Accepted:
April, 20, 2004
This work was supported by a grant from the National Natural Science Foundation
of China (General Program) (No. 30000032)
*Corresponding author: Tel, 86-28-8541-0672; E-mail, [email protected]