Chemistry Reference
In-Depth Information
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3.3.3
Adducts Containing Catalytic Modules Synthesized Prior to Incorporation into Polymers
To develop a methodology applicable to the design of a wide range of multinuclear
active sites on the backbones of insoluble polymers we prepared a molecular entity,
composed of various catalytic elements, with a precisely defined structure and then
attached it to a polymeric backbone. Thus, we synthesized catalytic modules contain-
ing one, two, or four metal-chelating sites, which were subsequently attached to a poly-
styrene derivative to produce
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-
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[55].
These polymer metallocatalysts effectively cleaved peptide bonds of myoglobin by
hydrolysis. Proteolytic activity increased considerably as the catalytic group density was
raised: the ratio of k
cat
/K
m
was 1:13:100 for the mono-, di-, and tetranuclear catalysts,
respectively. In the degradation of myoglobin by the dinuclear catalyst (
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), two pairs of
intermediate proteins accumulated, as revealed by MALDI-TOF MS of the reaction
mixture (Figure 3.11). To identify the cleavage sites leading to the formation of the
protein fragments, C-terminal sequencing was carried out by incubating the inter-
mediate proteins with carboxypeptidase A. Analysis based on MALDI-TOF MS of
the products obtained by treatment with carboxypeptidase A identified the peptide
linkages of Gln(91)-Ser(92) and Ala(94)-Thr(95) as the initial cleavage sites leading
to the formation of the protein fragments.
