Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.1.1 (asparaginase)
 2,695 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Asparaginase [EC 3.5.1.1.] of Escherichia coli, an anti-tumor enzyme, was inactivated in a time-dependent fashion by mushroom tyrosinase [EC1.14.18.1.]. The inactivation did not proceed, however, when heat-inactivated tyrosinase was used. Exculusion of the atmospheric oxygen or addition of diethyldithiocarbamate, a copper selective chelating agent, prevented the inactivation. The difference absorption spectrum of tyrosinase-inactivated asparaginase versus intact asparaginase exhibited the appearance of marked absorption peaks at 300 and 350 nm. These results indicate that the tyrosyl residue(s) of asparaginase, which is essential for the activity is enzymatically modified by tyrosianes.
 ...
PMID:Studies of enzyme-catalyzed modification of proteins. I. Tyrosinase-catalyzed modification of asparaginase. 81 77

In a previous study we demonstrated thirteen amino acids to be essential and two to be partially essential for lymphocyte proliferation. Arginine is one of the essential amino acids, and the highly purified arginase strongly inhibited lymphocyte proliferation. The modulation of lymphocyte growth by various amino acid-degrading enzymes was studied. Peripheral lymphocytes were cultured in RPMI 1640 with or without amino acid-degrading enzyme for 72 h. A total of 17 commercial L-amino acid-degrading enzymes were studied. At 10 micrograms/ml, both lysine decarboxylase and asparaginase completely inhibited lymphocyte proliferation, arginase resulted in 78% inhibition and tyrosinase 57% inhibition. Other enzymes inhibited less than 20% lymphocyte proliferation; they included alanine dehydrogenase, arginine decarboxylase, aspartase, glutamic decarboxylase, glutamic dehydrogenase, glutaminase, histidase, histidine decarboxylase, leucine dehydrogenase, phenylalanine decarboxylase, phenylalanine hydroxylase, tryptophanase, and tyrosine decarboxylase. All four enzymes that strongly inhibited lymphocyte proliferation degraded amino acids that are essential for lymphocyte growth.
 ...
PMID:Modulation of lymphocyte proliferation by enzymes that degrade amino acids. 212 55

This study suggests the presence of an entero-portal recirculation of amino acids. Endogenous sources of amino acids are secreted at high concentration into the small intestine. Most of the amino acids are absorbed as the content passes down the small intestine. Plasma amino acid concentrations are on the average only 1-5% of the concentrations in the duodunum. This is true even in rats on 24 hours of water and sugar with no exogenous sources of amino acids. For example, the PLASMA:DUODENUM concentrations (mumole/litre) are: Asparagine 37:7164, Tyrosine 94:9579, and glutamine/histidine 409:9708. This entero-portal recirculation of amino acids means the potential of a method for specific depletion of body amino acids by oral ingestion of bioreactants like immobilized enzymes. Preliminary studies used artificial cells to immobilize asparaginase,glutaminase and tyrosinase by microencapsulation. Six hours after 1 oral administration, asparagine, glutamine and tyrosine in the ileum were lowered to 10% of the level of the control. Artificial cells containing no enzymes were used as the control.
 ...
PMID:Plasma/intestinal concentration patterns suggestive of entero-portal recirculation of amino acids: effects of oral administration of asparaginase, glutaminase and tyrosinase immobilized by microencapsulation in artificial cells. 315 Sep 43

Oral binders remove intestinal bile acid and prevent its reabsorption and recycling thereby lowering systemic cholesterol levels. The results in this paper demonstrate the presence of another extensive enterorecirculation for amino acids. Pancreatic and other glandular secretions into the intestine contain large amounts of proteins, enzymes and polypeptides. Tryptic digestion converts these into amino acids which are then reabsorbed back into the body as they pass down the intestine. This paper shows that this forms a large enterorecirculation of amino acids between the body and intestine. The dietary protein source of amino acids is negligible when compared to the endogenous source, since this paper shows that protein-free diet did not alter the intestinal amino acid concentration. This raises the possibility of using this for the selective depletion of specific body amino acids. In this paper we use a phenylketonuria (PKU) model in rats to test the use of this hypothesis. In PKU rats, artificial cells microencapsulated phenylalanine ammonia lyase (PAL) given orally is more effective than a phenylalanine-free diet. The enzyme artificial cells are more efficient in lowering PHE in the intestine, plasma and cerebrospinal fluid. Compared to PKU on PHE-free diet, this has resulted in better weight gain and general physical condition. Preliminary studies also show that artificial cells microencapsulated asparaginase, glutaminase and tyrosinase given orally can deplete the corresponding amino acid from the intestine.
 ...
PMID:A new theory of enterorecirculation of amino acids and its use for depleting unwanted amino acids using oral enzyme-artificial cells, as in removing phenylalanine in phenylketonuria. 771 40

We studied the effects of polyphenol oxidase and asparaginase on microorganism adhesion to buccal epithelial cells. These enzymes reduced adhesion of pathogenic microorganisms (uropathogenic and Escherichia coli, Salmonella enteritidis, Entamoeba spp., Influenza virus, Candida albicans, Streptococcus spp.) and had virtually no effect on adhesive characteristics of probiotic variants of Escherichia coli and Lactobacillus fermentum.
 ...
PMID:Effects of asparaginase and polyphenol oxidase on adhesive characteristics of microorganisms. 1217 Mar 8

Porphyromonas gingivalis is a well-adapted pathogen of the periodontal pocket distinguished by its wide array of proteolytic activities and its ability to adhere to multiple substrata in the oral cavity. Microbial proteins with binding functions (such as adhesins and enzymes) very often contain critical tyrosine residues, supported by one or more asparagines in the binding cleft. This study investigates the reduction in adhesiveness and in proteolytic activity after treating P. gingivalis with the tyrosine- and asparagine-targeting enzymes polyphenol oxidase (PPO) and asparaginase (ASG). Cysteine protease activity was reduced by pretreatment with both enzymes, while the trypsin-like activity was affected only by PPO. Adhesion to buccal epithelial cells, laminin and fibronectin as well as hemagglutination was reduced by one or both of the enzymes. PPO, but not ASG, reduced the coaggregation of P. gingivalis with Actinomyces naeslundii. Treatment with these enzymes might provide an alternative to traditional antimicrobial strategies.
 ...
PMID:Virulence factors of Porphyromonas gingivalis are modified by polyphenol oxidase and asparaginase. 1293 May 24