Unit:
Τομέας Βιοχημείας Μοριακής ΒιολογίαςLibrary of the School of Science
Dissertation committee:
Σίδερης Διαμάντης Αναπλ. Καθηγ.(Επιβλέπων), Φραγκούλης Εμμανουήλ Καθηγ., Βοργιάς Κωνσταντίνος Καθηγ.
Original Title:
Λεπτομερής ενζυμικός χαρακτηρισμός μιας νέας ανθρώπινης ριβονουκλεάσης
Summary:
The RNase κ family is an orthologous protein family, represented in a wide
range of metazoans expanding from Cnidaria to mammals. The present thesis
concerns the human representative of the RNase κ family. The further enzymatic
study of human RNase κ constituted the first goal, while the second objective
was the identification of functional amino acids.
Concerning our first goal, human RNase κ was found to specifically hydrolyze
the ApG and ApU bonds in single stranded RNA substrates, while its enzymatic
activity was proved to be strongly affected by the nucleotide sequence
extending on both sides of the cleavage site. Moreover, we demonstrated that
cysteine residues 6 and 69 of the human protein form an intramolecular
disulfide bond, that is necessary for its catalytic activity. On the other
hand, the remaining cysteine residues 7, 14 and 85 are not implicated in the
enzymatic activity. Finally, the site-directed mutagenesis of conserved amino
acid residues resulted in the identification of an arginine residue responsible
for the non-specific binding of the RNA substrate.
Keywords:
Ribonuclease κ, Disulfide bonds, Catalytic activity, Site-directed mutagenesis , RNA decay
Number of references:
239
Number of pages:
vii, 213
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