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

The L-asparaginase (ASN) from Escherichia coli AS1.357 was cloned as a DNA fragment generated using polymerase chain reaction technology and primers derived from conserved regions of published ASN gene sequences. Recombinant plasmid pASN containing ASN gene and expression vector pBV220 was transformed in different E. coli host strains. The activity and expression level of ASN in the engineering strains could reach 228 IU/mL of culture fluid and about 50% of the total soluble cell protein respectively, more than 40-fold the enzyme activity of the wild strain. The recombinant plasmid in E. coli AS1.357 remained stable after 72 h of cultivation and 5 h of heat induction without selective pressure. The ASN gene of E. coli AS1.357 was sequenced and had high homology compared to the reported data.
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PMID:Cloning and expression of L-asparaginase gene in Escherichia coli. 1169 66

One of the hirudin variants HV3 was efficiently expressed in Escherichia coli using the L-asparaginase II signal sequence and the product was secreted into the culture medium. For the secretory manufacture of HV3, the L-asparaginase II signal sequence containing a single NheI restriction site at its 3' end was designed using the degenerate codons and PCR-amplified from E. coli chromosomal DNA. The synthetic HV3 coding sequence was fused to the signal sequence in-frame by its 5' NheI restriction site. The above signal-HV3 fusion gene was inserted into an expression vector pTA, which was derived from pkk223-3 such that its expression was under the control of the tac promotor. The resulting HV3 secretion expression vector pTASH thus constructed was introduced into an E. coli host cell AS1.357 with high L-asparaginase II producing level. After inducing with IPTG, the expression product was efficiently secreted into the culture medium and shake-flask culturing gave a yield of approximately 5 x 10(5)ATU/L (approximately 60mg/L). The secreted HV3 was easily purified from culture supernatant using ultrafiltration, ion-exchange column chromatography, and FPLC reverse-phase chromatography. The purified rHV3 from the culture supernatant had the expected N-terminal amino sequence and strong antithrombin activity, suggesting that the signal sequence was completely removed and the product was processed accurately during the secretion process.
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PMID:Efficient expression and secretion of recombinant hirudin III in E. coli using the L-asparaginase II signal sequence. 1218 23