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ISSN 0582-9879 Acta Biochim et Biophysica Sinica 2004, 36(2):99-104 CN 31-1300/Q
Effect of Zn(II) on the
Structure and Biological Activity of Natural β-NGF
Guang-Hua ZHAO, Ping
YU1, Xiao-Song HU*, and Lei ZHAO1
( College of Food Science & Nutritional Engineering, China Agricultural
University, Beijing 100083, China;
1Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences,
Beijing 100071, China )
Abstract Only β-NGF, the
subunit of the 7S NGF complex, exhibits NGF activity, but the function of the
zinc ion in native β-NGF has received little attention. Flameless atomic absorption
spectroscopy (FAAS) measurements reveal that native β-NGF contains Zn(II) with
a Zn(II)/β-NGF stoichiometry of 1:14.6. The presence of Zn(II) in the native
molecule results in significant changes of the secondary structure and local
tertiary structure around Trp(s) with respect to those of apo β-NGF, as suggested
by spectra of fluorescence and circular dichrosim. Stopped-flow studies show
that there are at least two steps during the interaction of Zn(II) with the
apo form. In comparison with its apo form, the native β-NGF shows a higher ability
to trigger the proliferation of TF1 cells and mediate the survival of PC12.
Thus it is most likely that the structural changes caused by the presence of
Zn(II) directly lead to the increase in the biological activity of β-NGF. All
results indicate that Zn(II) in native β-NGF plays an important role in the
structure and the biological activity of the protein.
Key words Zn(II); β-NGF;
apo β-NGF; secondary structure; tertiary structure; biological activity
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Received: October 8, 2003 Accepted:
December 8, 2003
*Corresponding author: Tel, 86-10-62343553; Fax, 86-10-62343553; E-mail, [email protected]