Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.64 (proteinase K)
 4,071 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A procedure is described for purification of the primary bactericidal component of normal rabbit serum active in vitro against Bacillus subtilis. A 65 000-fold increase in specific bactericidal activity per milligram of serum protein was obtained, yielding a low molecular weight, heat-stable polypeptide fraction (PC-III) exhibiting biological activity at protein concentrations below 10 ng/mL. This preparation appeared homogeneous as judged by column chromatography and analytical NaDodSO4-polyacrylamide gel eletrophoresis; recovery of serum bactericidal activity was routinely greater than 80%. Analysis of dansylated or 125I-labeled samples in peptide-resolving polyacrylamide gels revealed a single band with an Mr of 1800. Optimal antibacterial activity of PC-III against B. subtilis occurred at an ionic strength of 0.24 and was absolutely dependent upon divalent cations; calcium was the most effective. Under optimum conditions, 4 ng/mL of PC-III reduced the viability of B. subtilis test innocula by 90% within 10 min at 37 degrees C. Listeria monocytogenes, Escherichia coli, and Salmonella typhimurium were all sensitive to the action of PC-III, but higher bactericide concentrations were required to produce similar reductions in viability as observed with B. subtilis. All strains were killed by PC-III concentrations well below 1 microgram/mL, roughly that found in normal serum. The activity of PC-III preparations was significantly reduced by pretreatment with trypsin or proteinase K but not by neuraminidase or periodate.
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PMID:Antibacterial peptide from normal rat serum. 1. Isolation from whole serum, activity, and microbicidal spectrum. 679 8

Gallium is an iron mimetic which has recently been repurposed as an antibacterial agent due to its capability to disrupt bacterial iron metabolism. In this study, the antibacterial activity of gallium nitrate [Ga(NO3)3] was investigated in complement-free human serum (HS) on 55 Pseudomonas aeruginosa clinical isolates from cystic fibrosis and non-cystic fibrosis patients. The susceptibility of P. aeruginosa to Ga(NO3)3 in HS was dependent on the bacterial ability to acquire iron from serum binding proteins (i.e., transferrin). The extent of serum protein degradation correlated well with P. aeruginosa growth in HS, while pyoverdine production did not. However, pyoverdine-deficient P. aeruginosa strains were unable to grow in HS and overcome iron restriction, albeit capable of releasing proteases. Predigestion of HS with proteinase K promoted the growth of all strains, irrespective of their ability to produce proteases and/or pyoverdine. The MICs of Ga(NO3)3 were higher in HS than in an iron-poor Casamino Acids medium, where proteolysis does not affect iron availability. Coherently, strains displaying high proteolytic activity were less susceptible to Ga(NO3)3 in HS. Our data support a model in which both pyoverdine and proteases affect the response of P. aeruginosa to Ga(NO3)3 in HS. The relatively high Ga(NO3)3 concentration required to inhibit the growth of highly proteolytic P. aeruginosa isolates in HS poses a limitation to the potential of Ga(NO3)3 in the treatment of P. aeruginosa bloodstream infections.
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PMID:Pyoverdine and proteases affect the response of Pseudomonas aeruginosa to gallium in human serum. 2614 86