Disintergration acid. Uricase enzyme is highly conserved present in

Disintergration of DNA molecules in human body results in
Uric acid, a natural product of metabolism, which is routinely expelled from
the body. On the other hand, high accretion of uric acid in the body and or low
elimination rate of it is firmly linked to pathogenesis of uman diseases such
as gout and hyperuricemia. It is extremely affected through the high
consumption of food rich in purine. Hyperuricemia results from an
imbalance between the rates of production and excretion of uric acid. Due to
the low solubility (6 mg/dL, 20 C) of uric acid, long-term hyperuricemia leads
to destructive crystalline urate deposits around joints, in soft tissues, and
in some organs, causing a number of disorders, including gout and urate
nephropathy associated with tumor lysis syndrome. Studies have also shown that
hyperuricemia in humans can increase the risk of cardiovascular diseases,
chronic nephropathy, impaired renal function, hypertension, and stroke. Due to
those severe complications of hyperuricemia, its therapeutic countermeasures
have attracted great attention in the medical community. This disease afflicts
more than 10 million patients worldwide, and its incidence is on the rise. More
than three decades ago allopurinol was considered as a first line drug which
regulate uric acid synthesis by inhibiting xanthine oxidase (XO) enzyme. In
addition to allopurinol, febuxostat is also used to reduce the synthesis of
uric acid by inhibiting the XO enzyme and is approved by the European Medical Agency
in 2008 and US FDA in 2009. In contrast to allopurinol it acts on both reduced
as well as oxidised form of XO. Partial relief from inflammation can be
obtained by administration of hydroxychloroquine and non steroidal  anti -inflammatory drugs. However these drugs
are prone to have enormous side effects, so in order to regulate the uric acid
level in serum or soft tissues, enzymatic treatment is considered to be the
better way without any side effects. Uricase (urate oxidase) EC 1.7.3.3 a
tetramer therapeutic enzyme which oxidatively opens the purine ring of uric
acid and forms allantoin, CO2 and H2O. Allantoin is a soluble molecule in
plasma, which can be easily eliminated through the kidneys as it is 5–10 times
more soluble than uric acid. Uricase enzyme is highly conserved present in
mammals, plants, fungi, bacteria and yeasts but is absent in humans due to
evolutionary mutations in uricase gene. Therefore,
uricase from various microorganisms has been intravenously administered for
nearly 40 years to treat hyperuricemia and gout. Rasburicase
(Fasturtec®), a recombinant form of Uox from Aspergillus flavus, is the first
marketed Uox preparation for the treatment and prophylaxis of acute
hyperuricemia resulting from tumor lysis syndrome in children with cancer. Its
outstanding ability to decrease uric acid level and dissolve tophi makes
Uox-based therapy a more promising strategy for the treatment of hyperuricemia.
However, the clinical use of rasburicase is limited by its immunogenicity and
short half-life. In 2010, pegloticase (Krystexxa), a PEGylated chimeric
porcine-baboon Uox, was approved by the USA Food and Drug Administration (FDA)
for treatment of chronic gout in adult patients refractory to conventional
therapy. With a higher sequence homology to hypothetic human uricase and PEGylation,
the immunogenicity of pegloticase is significantly reduced and half-life
prolonged. In addition to the FDA approved porcine–baboon chimera (PBC),
investigations on several other chimeric uricases have also been reported, such
as canine–human chimeric uricase and porcine–human chimeric uricase. The
development of therapeutic uricase for human use is an intractable challenge as
activity, stability, and immunoreactivity should all be taken into
consideration. As such, the medical community has a strong interest in
developing a recombinant “human-like” uricase to treat hyperuricemia and gout.
Uricase is localized inside microorganisms, especially Bacillus pasteurii,
Proteus mirabilis, and Escherichia coli, while other microorganisms could
produce them extracellularly by changing certain components of the culture
media as in Streptomyces albosriseolus, Microbacterium, Bacillus
thermocatenulatus, Candida tropicalis, and Pseudomonas aeruginosa. Streptomyces exofolitus isolated from soil by Magda
et al were found to be high producer of uricase.  Uricase is a therapeutic enzyme belonging to
the class of the oxidoreductases, which catalyses the oxidation of uric acid,
producing allantoin and acting in the purine degradation pathway. The enzyme exists as a tetramer of identical subunits, each containing a
possible type 2 copper-binding site. Urate oxidase is a homotetrameric enzyme containing four identical active sites situated at the
interfaces between its four subunits. It is unique among the oxidases in that it does not require a metal atom or an organic co-factor
for catalysis.

Uric acid + O2 + H2O ? H2O2 + allantoin + CO2

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Uricase is useful for enzymatic
determination of uric acid in biological fluids for clinical analysis. Uricase
can be also used as a protein drug to reduce toxic urate accumulation. Immobilized
uricase can be used as a uric acid biosensor. Uricase is also used as an
additive in commercial formulations of hair coloring agents. Although uricase
has been produced using several microbial sources, due to its increasing
importance in treatment and in diagnosis, new sources of uricase are sought
aiming to produce better yield of the enzyme. The largest and most important
genus in the order actinomycetales are Streptomyces. It comprises up to
90% of actinomycetes isolated from the soil samples, it is prolific producers
of bioactive compounds such as antibiotics and enzymes which have important
applications both in medicine and agriculture. The present study aimid at searching for potential uricase producing streptomyces
source and cloning and expression and purification it.