| Summary: | 碩士 === 國立臺灣大學 === 生化學研究所 === 81 === Because a rabbit antiserum against bovine pancreatic(bp-)
DNase had an inhibitory effect on bp-DNase butnot on porcine
pancreatic (pp-) DNase, we raised an antiserum against pp-DNase
and analyzed for its inhibitory effects.This anti-pp-DNase
antiserum inhibited pp-DNase but not bp-DNase.We identified 15
peptides which account for over 90 % of the entire sequence
of DNase. Four of the 15 peptides contain antigen determinat
sites as determined with anti bpDNase polyclonal antibody and
one of four peptides bp-DNase was positive using two monoclonal
anti-bp-DNase antibodies. We found the inhibitery effect of
the polyclonal antibody can be recovered by the Cu-iodoacetate
inactivated DNase.But the effect can not be recovered by the
three protease digests of DNase. We looked for a peptide that
is 1] among the non-conservable protein sequence regions
between bp-DNase and pp-DNase 2] antigenic regions 3] the
regions is sensitive to hydrolysis by trypsin, chymotrypsin
and thermolysin.This peptide is a 21 residue peptide
corresponding to bp-DNase which was chemically synthesized and
able to reverse the inhibitory effect. The antibody inhibitory
effect depend on the metal ions used (Mn2+= Co2+= Ca2+ plus
Mg2+> Mg2+). This order is the same as the order of metal ion
for SiteI.Metal ions also have have effects on the mode of
action of DNase. The DNase catalyzed pBR322 hydrolysis
produced a significant amount of double strand cut with Mn2+,
Co2+ or Mg2+ plus Ca2+ as activators and no double strand cuts
were observed with only Mg2+as activator.The anti-bp- DNase
antiserum inhibited the DNase action on double strand cut
with Mn2+, Co2+ or Mg2+ plus Ca2+ as activators. The
inhibitory effect of the antiserum is caused by the binding of
an antibodyto Site I. The binding produce a reduced DNase
hydrolysis rate and the inhibition of double cuts on duplex DNA.
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