- Tytuł:
- Structural aspects of l-asparaginases, their friends and relations
- Autorzy:
-
Michalska, Karolina
Jaskolski, Mariusz - Powiązania:
- https://bibliotekanauki.pl/articles/1041150.pdf
- Data publikacji:
- 2006
- Wydawca:
- Polskie Towarzystwo Biochemiczne
- Tematy:
-
Ntn-hydrolase
l-asparaginase
isoaspartyl peptidase - Opis:
- Enzymes capable of converting l-asparagine to l-aspartate can be classified as bacterial-type or plant-type l-asparaginases. Bacterial-type l-asparaginases are further divided into subtypes I and II, defined by their intra-/extra-cellular localization, substrate affinity, and oligomeric form. Plant-type l-asparaginases are evolutionarily and structurally distinct from the bacterial-type enzymes. They function as potassium-dependent or -independent Ntn-hydrolases, similar to the well characterized aspartylglucosaminidases with (αβ)2 oligomeric structure. The review discusses the structural aspects of both types of l-asparaginases and highlights some peculiarities of their catalytic mechanisms. The bacterial-type enzymes are believed to have a disordered active site which gets properly organized on substrate binding. The plant-type enzymes, which are more active as isoaspartyl aminopeptidases, pose a chemical challenge common to other Ntn-hydrolases, which is how an N-terminal nucleophile can activate itself or cleave its own α-amide bond before the activation is even possible. The K+-independent plant-type l-asparaginases show an unusual sodium coordination by main-chain carbonyl groups and have a key arginine residue which by sensing the arrangement at the oligomeric (αβ)-(αβ) interface is able to discriminate among substrates presented for hydrolysis.
- Źródło:
-
Acta Biochimica Polonica; 2006, 53, 4; 627-640
0001-527X - Pojawia się w:
- Acta Biochimica Polonica
- Dostawca treści:
- Biblioteka Nauki
Artykuł