Regulation of ?-aminoadipyl-cysteinyl-valine, isopenicillin N synthetase, isopenicillin N isomerase and deacetoxycephalosporin C synthetase by nitrogen sources in Streptomyces lactamdurans

1985 ◽  
Vol 22 (1) ◽  
Author(s):  
Jos�M. Castro ◽  
Paloma Liras ◽  
Jes�s Cort�s ◽  
JuanF. Mart�n
Keyword(s):  
Nitrogen Sources ◽  
Deacetoxycephalosporin C Synthetase ◽  
Isopenicillin N Synthetase ◽  
Isopenicillin N

Ammonium repression of cephalosporin production by Streptomyces clavuligerus

1985 ◽  
Vol 31 (8) ◽  
pp. 736-743 ◽  
Author(s):  
Alfredo F. Braña ◽  
Saul Wolfe ◽  
Arnold L. Demain
Keyword(s):  
Specific Activity ◽  
Relative Proportion ◽  
Streptomyces Clavuligerus ◽  
Defined Medium ◽  
Inhibitory Effects ◽  
Rate Limiting Step ◽  
Deacetoxycephalosporin C Synthetase ◽  
Isopenicillin N Synthetase ◽  
Rate Limiting ◽  
Isopenicillin N

Production of β-lactam antibiotics took place during growth of Streptomyces clavuligerus in chemically defined medium. The specific activities of isopenicillin N synthetase ("cyclase"), isopenicillin N epimerase, and deacetoxycephalosporin C synthetase ("expandase") increased during the exponential phase of growth. Specific cephalosporin productivity during fermentation followed a similar pattern, reaching a maximum near the end of the growth phase and decaying rapidly in the stationary phase. Ammonium chloride depressed cephalosporin production, presumably as a result of repression of cyclase and expandase formation, but not of epimerase. No inhibitory effects on enzyme activity by ammonium were found. Addition of tribasic magnesium phosphate [Mg3(PO4)2∙8H2O] prevented the repression of cyclase and markedly stimulated cephalosporin production. Cephamycin C and, in smaller amounts, O-carbamoyldeacetylcephalosporin C were the only cephalosporins detected. Growth with ammonium resulted in lower titers of both compounds, and did not change the relative proportion of each. The correlation found between cephalosporin productivity and cyclase specific activity in different media suggests that formation of this enzyme may be the rate-limiting step in the pathway.

Penicillin biosynthesis: structure–reactivity profile of unsaturated substrates for isopenicillin N synthetase

1986 ◽  
pp. 273-275 ◽  
Author(s):  
Jack E. Baldwin ◽  
Robert M. Adlington ◽  
Amit Basak ◽  
Sabine L. Flitsch ◽  
Andrew K. Forrest ◽  
...  
Keyword(s):  
Penicillin Biosynthesis ◽  
Isopenicillin N Synthetase ◽  
Isopenicillin N

Cloning and characterization of the isopenicillin N synthetase gene mediating the formation of the β-lactam ring in Aspergillus nidulans

Gene ◽  
1987 ◽  
Vol 57 (2-3) ◽  
pp. 171-181 ◽  
Author(s):  
Daniel Ramón ◽  
Laura Carramolino ◽  
Cristina Patiño ◽  
Flora Sánchez ◽  
Miguel Angel Peñalva
Keyword(s):  
Aspergillus Nidulans ◽  
Lactam Ring ◽  
Isopenicillin N Synthetase ◽  
Isopenicillin N

scholarly journals Purification and characterization of cloned isopenicillin N synthetase.

1987 ◽  
Vol 40 (5) ◽  
pp. 652-659 ◽  
Author(s):  
JACK E. BALDWIN ◽  
STEPHEN J. KILLIN ◽  
ANDREW J. PRATT ◽  
JOHN D. SUTHERLAND ◽  
NICHOLAS J. TURNER ◽  
...  
Keyword(s):  
Purification And Characterization ◽  
Isopenicillin N Synthetase ◽  
Isopenicillin N

A coupled enzyme assay for isopenicillin N synthetase

1985 ◽  
Vol 145 (1) ◽  
pp. 183-187 ◽  
Author(s):  
Jack E. Baldwin ◽  
Simon E. Moroney ◽  
Hong-Hoi Ting
Keyword(s):  
Enzyme Assay ◽  
Isopenicillin N Synthetase ◽  
Isopenicillin N

Studies on the ring-cyclization and ring-expansion enzymes of β-lactam biosynthesis in Cephalosporium acremonium

1983 ◽  
Vol 29 (5) ◽  
pp. 488-496 ◽  
Author(s):  
Jutta Kupka ◽  
Yong-Qiang Shen ◽  
Saul Wolfe ◽  
Arnold L. Demain
Keyword(s):  
Micrococcus Luteus ◽  
Gel Filtration ◽  
Ring Expansion ◽  
Exchange Chromatography ◽  
Cephalosporium Acremonium ◽  
Competitive Inhibitors ◽  
Isopenicillin N Synthetase ◽  
Soluble Enzymes ◽  
Temperature Optima ◽  
Isopenicillin N

Micrococcus luteus was found to be very sensitive to isopenicillin N and was used as assay organism for purification of the enzyme isopenicillin N synthetase, which cyclizes δ-(L-α-aminoadipyl)-L-cysteinyl-D-valine to isopenicillin N. Purification of the enzyme from the crude extract obtained by sonication of mycelia of Cephalosporium acremonium CW-19 was carried out by ammonium sulfate precipitation, desalting with Sephadex G-25, gel filtration on LKB ultrogel AcA44 or ion-exchange chromatography on DEAE-Sepharose. The cyclization enzyme was separated from the ring-expansion enzyme and was purified considerably more than 50-fold by this procedure. Using the purified enzyme, we found that the disulfide bis-δ-(L-α-aminoadipyl)-L-cysteinyl-D-valine required reduction to δ-(L-α-aminoadipyl)-L-cysteinyl-D-valine in order to behave as a substrate. The enzyme activity was stimulated by FeSO4 and ascorbate, but other cofactors, including α-ketoglutarate, were inactive. In addition to δ-(L-α-aminoadipyl)-L-cysteinyl-D-valine, the enzyme converted adipyl-L-cysteinyl-D-valine, N-acetyl-δ-(L-α-aminoadipyl)-L-cysteinyl-D-valine, and glycyl-δ-(L-α-aminoadipyl) L-cysteinyl-D-valine to penicillins. All of these latter peptides were competitive inhibitors of the cyclization reaction. The Km of the cyclization enzyme is 10 times higher than that of the ring-expansion enzyme, deactoxycephalosporin C synthetase. The pH and temperature optima of the two enzymes were rather similar. Phosphate inhibited ring expansion, but not cyclization. Both enzymes appear to be soluble enzymes of about 31 000 molecular weight.

Sign in / Sign up

Export Citation Format

Share Document