ΜΕΛΕΤΗ ΤΗΣ L-ΑΣΠΑΡΑΓΙΝΑΣΗΣ ΣΤΟ ΠΡΩΤΟΖΩΟ T. PYRIFORMIS

L-ASPARAGINASE OF TETRAHYMENA PYRIFORMIS IS A MEMBRANE BOUND ENZYME. MOST OF ITS ACTIVITY ( 80%) IS ASSOCIATED WITH MICROSOMES AND THE REMAINING WITH THE PELLICLES. INTACT PROTOZOA CAN HYDROLYZE L- ASPARAGINE AT A RATIO OF 60 NMOLE/10 6 CELLS/HR WHILE THE INFLUX OF THIS AMINOACID IS ONLY 8 NMOLE/10 6 CELLS/HR. UPON THESE STUDIES L- ASPARAGINASE OF PELLICLES CAN BE CONSIDERED AS AN ECTOENZYME. L- ASPARAGINASE CAN BE SOLUBILIZED BY CHAOTROPIC AGENTS, N-BUTANOLE OR BY 0.1 M PHOSPHATE BUFFER PH 8.0 AFTER PRETREATMENT OF THE MICROSOMES WITH 2% W/VTRITON X-100. PURIFICATION OF L-ASPARAGINASE WAS ACHIEVED BY CHROMATOGRAPHY ON PHENYL-SEPHAROSE CL-4B AND SEPHAROSE 6B COLUMNS. THE SPECIFIC ACTIVITY OF THE PURIFIED L-ASPARAGINASE WAS 5.5 UNITS/MG PROTEIN AND THE PURIFICATION FACTORWAS AROUND 300. L-ASPARAGINASE SHOWS A MOLECULAR WEIGHT OF 230,000 DETERMINEDBY CHROMATOGRAPHY ON SEPHAROSE 6B COLUMN AND CONSISTS OF SIX SUBUNITS OF 39,000 MOLECULAR WEIGHT AS DETERMINED BY SDS ELECTROPHORESIS. THE KM OF THE ENZYMEIS 2.2 MM AND ITS ISOELECTRIC POINT IS 6.8. IT DOES NOT HYDROLYZE L-GLUTAMINENOR D-ASPARAGINE AND FROM THE ANALOGUES TESTED IT HYDROLYZES ONLY A- N-METHYL-D,L-ASPARAGINE, WHILE ANALOGUES WITH SUBSTITUENTS IN THE B- POSITION INHIBIT L-ASPARAGINASE ACTIVITY IN A COMPETITIVE MANNER. ITS OPTIMUM PH IS 8.6 IN 50 MMTIRS-HCL AND 1 MM B-MERCAPTOETHANOL. FROM THE IONS TESTED ONLY ZN2+ INHIBITS 50% THE ENZYME ACTIVITY AT A 20 MM CONCENTRATION. L-ASPARAGINASE ACTIVITY REACHES MAXIMUM VALUES AT THE STATIONARY PHASE OF GROWTH OF TETRAHYMENA PYRIFORMISAND FLUCTUATES UPON THE GROWTH CONDITIONS AND THE COMPOSITION OF THE MEDIUM.

Grantor dc:publisher

Aristotle University Of Thessaloniki (AUTH)

Year dc:date

1987

Author dc:creator

• Τριανταφύλλου, Δημήτριος

• L-asparaginase
• L-ASPARAGINASE OF T. PYRIFORMIS
• L-ασπαραγινάση
• L-ΑΣΠΑΡΑΓΙΝΑΣΗ ΔΕΣΜΕΥΜΕΝΗ ΣΕ ΜΕΜΒΡΑΝΕΣ
• MEMBRANE BOUND L-ASPARAGINASE
• PURIFICATION OF L-ASPARAGINASE
• STUDY OF PROPERTIES OF L-ASPARAGINASE
• Βιοχημεία
• Ενζυμολογία
• ΚΑΘΑΡΙΣΜΟΣ ΤΗΣ L-ΑΣΠΑΡΑΓΙΝΑΣΗΣ
• ΜΕΛΕΤΗ ΤΩΝ ΙΔΙΟΤΗΤΩΝ ΤΗΣ L-ΑΣΠΑΡΑΓΙΝΑΣΗΣ
• Φυσικές Επιστήμες
• Χημεία
• Natural Sciences
• Chemical Sciences

Language dc:language

gre

Identifier

10.12681/eadd/0300

OAI identifier oai:identifier

oai:10442/0300