Degradation of N5-(2-hydroxyethyl)-L-glutamine and L-glutamic acid homopolymers and copolymers by papain
Jazyk angličtina Země Nizozemsko Médium print
Typ dokumentu časopisecké články
PubMed
1982924
DOI
10.1016/0141-8130(90)90003-s
PII: 0141-8130(90)90003-S
Knihovny.cz E-zdroje
- MeSH
- cirkulární dichroismus MeSH
- gelová chromatografie MeSH
- glutamáty chemie metabolismus MeSH
- koncentrace vodíkových iontů MeSH
- konformace proteinů MeSH
- kyselina glutamová MeSH
- papain metabolismus MeSH
- peptidy chemie metabolismus MeSH
- polymery MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- glutamáty MeSH
- kyselina glutamová MeSH
- papain MeSH
- peptidy MeSH
- poly-N(5)-(2-hydroxyethyl)glutamine MeSH Prohlížeč
- polymery MeSH
The rate of degradation of poly[N5-(2-hydroxyethyl)-L-glutamine] (PHEG), poly(L-glutamic acid) (PGA) and poly[HEG-co-GA] random copolymers by papain was measured in the pH range 4.0-7.5, employing the gel permeation chromatography method. The effect of the degree of ionization on the polymer conformation was measured by circular dichroism (c.d.). PHEG, which is uncharged, had a random coil conformation and an almost constant degradation rate within the whole pH interval. The ionization of PGA increased with increasing pH and was accompanied by conformational transition from helix to random coil. The hydrolysis of PGA by papain depended on pH with the optimum at about pH 5, indicating that both the high content of helix (at pH less than 5) and increasing charge density (at pH greater than 5), decreased the degradation rate. Contrary to PGA, pH profiles of the degradation rate of poly[HEG-co-GA] copolymers are monotonous and do not decrease at pH less than 5. In the copolymers the HEG residues act as a helix breaker and limit the formation of helical conformation. The role of structural features of a macromolecular substrate, i.e. the charge, helical conformation and the nature of amino acid residues, in the interaction between enzyme and polymer is discussed.
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