- Proteinase K.
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- Description
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- Proteinase K (EC 3.4.21.14) is isolated from fungus Tritirachium
album is a highly active serine protease of the subtilisin type.
The enzyme catalyzes hydrolysis of a wide variety of peptide bonds but
exhibits a preference for peptide bonds C-terminal to aromatic and uncharged
amino acids. M.W. approx. 28930 Da. Activity >30U/mg protein.
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- Unit definition
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One Anson unit liberates 1µM of Folin-positive amino acids per
min at pH 7.5 and 35°C using haemoglobin as substrate.
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- Reaction buffers
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- #B29 (x10): 500 mM Tris-HCl pH 7.5, 50 mM CaCl2. #B30 (x10,
for isolation of DNA and RNA isolation from blood, cells and tissue):
100 mM Tris-HCl pH 8.0, 50 mM EDTA, 5% SDS.Use enzyme in excess (30-45U)
to degrade 100 mg of solid tissue, pellet from 20 ml blood or 5x107
mammalian cells (1 ml suspension). The working concentration of the
enzyme should be 3-6U/ml in 10-15 ml of the lysis buffer. Incubation
time can range from 30 min to 18 h depending on the nature of the experiment.
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Reaction conditions
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Proteinase K is stable over a wide pH range (4.0-12.5); however, the
enzyme is normally used in pH range 7.5-9.0. The activity of Proteinase
K is severalfold higher at 50°C than at 37°C.The activity can
be stimulated addition of denaturing agents (0.5% SDS, 1% Triton X-100
and 1-4 M urea). The enzyme is inactivated by Pefabloc SC and inhibited
by diisopropyl phosphofluoridate (DFP) and phenylmethanesulfonyl fluoride
(PMSF).
When Ca2+ is removed from the enzyme, some of the catalytic
activity is lost because of long-range structural chanages. Because EDTA
is a component of the buffer solutions used for RNA/DNA isolation, digestion
is usually carried out under non optimal conditions. However, residual
activity in a presence of EDTA is sufficient to degrade most proteins.
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- Storage
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- Store at -20°C.
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- Applications
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- preparation of high-molecular weight DNA for PFGE and intact cellular
RNA; protein fingerprinting; removal of nucleases from preparations
of DNA and RNA; to study membrane protein topology and protein translocation
across membranes.
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Quality control
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activity, SDS-PAG purity, no contaminating nuclease activity.
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References
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1. Ebeling, W. (1974) Eur. J. Biochem. 47, 91-97. 2. Bajorath, J. et
al. (1988) Eur. J. Biochem. 176, 441-447.
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- Catalog #
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- P3.3
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P3.5
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Pack size
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500 U
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2500 U
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