Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:3.5.1.1 (
asparaginase
)
2,695
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Homogeneols
L-asparaginase
with anti-lymphoma activity was prepared from Vibrio succinogenes, an anaerobic bacterium from the bovine rumen. An overall yield of pure
L-asparaginase
of 40 to 45% and a specific activity of 200 +/- 2 IU per mg of protein was obtained. The pure enzyme can be stored at -20 degrees for at least 3 months with no loss of activity. The isoelectric point of the
L-asparaginase
is 8.74. No carbohydrate, phosphorus, tryptophan, disulfide, or sulfhydryl groups were detected. The enzyme has a molecular weight of 146,000 and a subunit weight of approximately 37,000. The Km of the enzyme for L-asparagine is 4.78 X 10(-5) M and the pH optimum of the
L-asparaginase
reaction is 7.3.
D-Asparagine
was hydrolyzed at 6.5% of the rate found with the L isomer. L-Glutamine and a variety of other amides were not hydrolyzed at significant rates; the activity of the enzyme for L-glutamine was 130- to 600-fold less than that of other therapeutically effective L-asparaginases of bacterial origin. The
L-asparaginase
from V. succinogenes is immunologically distinct from the
L-asparaginase
(EC-2) of Escherichia coli.
...
PMID:Purification and characterization of L-asparaginase with anti-lymphoma activity from Vibrio succinogenes. 1 Dec 11
Yeast strains sigma1278b and Harden and Young, which synthesize only an internal constitutive form of
L-asparaginase
, do not grow on D-asparagine, as a sole source of nitrogen, and whole cell suspensions of these strains do not hydrolyze D-asparagine. Strains X2180-A2 and D273-10B, which possess an externally active form of
asparaginase
, are able to grow slowly on D-asparagine, and nitrogen-starved suspensions of these strains exhibit high activity toward the D-isomer. Nitrogen starvation of strain X218O-A2 results in coordinate increase of D- and
L-asparaginase
activity; the specific activity observed for the D-isomer is approximately 20% greater than that observed for the L-isomer. It was observed, in studies with cell extracts, that hydrolysis of D-asparagine occurred only with extracts from nitrogen-starved cells of strains that synthesize the external form of
asparaginase
. Furthermore, the activity of the extracts toward the D-isomer was always higher than that observed with the L-isomer. A 400-fold purified preparation of external
asparaginase
from Saccharomyces cerevisiae X218U-A2 hydrolyzed D-asparagine with an apparent Km of 0.23 mM and a Vmax of 38.7 mumol/min per mg of protein.
D-Asparagine
was a competitive inhibitor of L-asparagine hydrolysis and the Ki determined for this inhibition was approximately equal to its Km. These data suggest that D-asparagine is a good substrate for the external yeast
asparaginase
but is a poor substrate for the internal enzyme.
...
PMID:Utilization of D-asparagine by Saccharomyces cerevisiae. 76 32
