Ali Nawaz*, Taha Shafi, Abdul Khaliq, Hamid Mukhtar and Ikram ul Haq.
Tyrosinase is the natural enzymes that can be obtained from the multiple sources like bacteria, fungi, plants and mammals and can only
purified to a very low degree. Different microbial strains were reported for efficient tyrosinases production like Streptomyces glaucescens,
Agaricus bisporus and Neurospora crassa. This enzymes is mainly involved in two step process i.e. hydroxylation of monophenols and
oxidation of O-diphnols for production of many pigments (black or brown pigments). Tyrosinase is useful in different industries such
as food, biomedical and pharmaceutical. Apart from that they can be applied for bioremediation. Waste water or contaminated soil
containing phenolic compounds can be detoxified through their action. Melanin pigment formed under the activity of tyrosinases is good
protection for mammals against UV radiations as well.
Tyrosinases, Melanin, Bioremediation, Polyphenols
Tyrosinases a group of binuclear copper enzymes and their closely
related compounds like catechol oxidases (known collectively
as polyphenol oxidases) found mainly in different groups of
bacteria, fungi, plants and animals that use phenolic compounds
as substrates and produce compounds like melanin and many
other polyphenolic products which are biologically very important
(Claus & Decker, 2006; Halaouli et al., 2006; Marusek et al.,
2006). Tyrosinase (EC 220.127.116.11) have dual functionality that
causes monophenolase activity (hydroxylation of monophenols
to o-diphenols) and diphenolase activity (oxidation of diphenoles
to o-quinones) (Fairhead &Thony-Meyer, 2012). This enzyme
is very important for alive organisms to do different functions,
like production of melanin for defensive mechanism against UV
radiations (Claus & Decker, 2006; Halaouli et al., 2006). For plants
it is important in the production of phenolic polymers like tannins,
lignin, flavonoids (Marusek et al., 2006) and for the regulation of
redox potential during plant cell respiration and healing of wounds
in plants (Mayer, 2006).
Tyrosinase ability to react with phenols makes it useful for
biotechnological, biosensor and biocatalysis applications
(Fairhead & Thony-Meyer, 2012; Jus et al., 2008; Jus et al.,
2009). It can be further applied for detoxification of water and soil
contaminated with phenolic compounds (Martorell et al.,2012), in
biosynthesis of L-DOPA (L-3,4-dihydoxyphenylalanine), as a drug
highly recommended for Parkinson’s disease patients (Seetharam
& Saville, 2002), and also as food additives due to their cross-
linking properties during food processing (Lantto et al.,2007;
Selinheimo et al., 2007). Tailoring polymers, like grafting of silk
proteins onto chitosan as a result of tyrosinase reaction is also
reported (Anghileri et al., 2007; Freddi et al., 2006). Tyrosinase in
immobilized form can act as electrochemical biosensors for verity
of phenolic compounds (Gu et al., 2009).
Streptomyces glaucescens is a source of best characterized
tyrosinase along with the fungal species like Agaricus bisporus
and Neurospora crassa. Tyrosinase from fungal and vertebrate
sources initiates the first step in melanin formation from tyrosine.
Plants have verity of phenolic substrates so these are oxidized by
tyrosinase as observed in browning pathway when plant tissues are
injured. Agaricus bisporus enzyme extract is highly homologous
to enzyme extract of mammals so this make it as a suitable model
for study on melanogenesis (Chang, 2009)
Structure of Tyrosinase :
Due to multiple sources of tyrosinase its structural properties are
diverse in nature along with their distribution in tissues and cells,
so no common protein is observed across all species (Mayer, 2006;
Jaenicke & Decker, 2003). The difference is observed in primary
structure, size, in post modification sites like active site and in glycosylation mechanism. Common thing in all tyrosinases is their
binuclear type III copper centre containing two copper atoms each connected with six histidine molecules in their active site. These
copper atoms are linked with atmospheric oxygen that catalysis the two different reactions (1) ortho-hydroxylation of monophenols and
(2) oxidation of o-diphenols to o-quinones. Crystal structure contain each copper coordinated with 3 histidine like in CuA and CuB as
shown in the figure 1 (a) and (b).
Figure 1: Structure of Tyrosinase
Human tyrosinases are glycoproteins which are membrane bounded and their monomers have more than one isoforms. Similarly
tyrosinases from bacteria like Streptomyces species have non-modified monomers of MW
30KDa (Wu et al., 2010).
Tyrosinase Sources :
Tyrosinase can be produced and extracted through number of organisms such as bacteria, fungi, plants and mammals (Table 1). Tyrosi
nases can be purified from these sources and studied for specific functioning.
Table 1: Sources of Tyrosinase
Purification methods for Tyrosinases :
Natural enzymes are difficult to purify so as tyrosinases are also show low degree purification as these are natural enzymes.
common methods used for purification of tyrosinases are by using ammonium sulfate, calcium salt or acetone precipitation (Mueller et
al., 1996). By varying ammonium sulfate co`ncentration the purification can be optimized as in some studies concentration varies from
35% to 70% (Kamahldin et al., 2004). For tyrosinases purification different columns like DEAE-cellulose (Fan and Flurkey
, 2004) or
size exclusion gel can also be performed (Wichers et al., 1996).
Methods for the purification of tyrosinase. Adopted from (Zaidi et al., 2014).
Applications in Different Industries
Tyrosinase is involved in the biosynthesis of melanin in the
melanosomes causing pigmentation of skin, hair and eyes in
mammals providing the protection against UV (Ando et al., 2007).
The enzyme plays a crucial part in immune response (primary)
and healing of wound in plants, various invertebrates as well as
sponges. It is significant for spore forming, protecting tissues ad
survival after some lesion or injury in fungi. It has a vital part
in protection of bacteria. The enzyme has important medical
applications including melanin synthesis for therapeutic purposes,
L-DOPA production, a drug utilized to treat the Parkinson's
disease, manufacturing antibiotic lincomycin and treating various
neurological diseases (Valipour& Burhan, 2016). Mushroom
tyrosinase has clinical application to treat vitiligo (Seo et al., 2003).
This enzyme produce hydroxyl tyrosol that has application of food
additive. This is employed in the food manufacturing industries,
for instance to make theaflavins, a collection of compounds in
black tea possessing anticancer and other properties (Valipour&
Burhan, 2016). Biopolymers are being developed by the food
industries that possess particular properties. They have functions
al., 2004). The properties of meat like capability of gel formation,
textural and binding properties are vital to manufacture various
meat products. The gelation of muscle proteins induced by the heat
is serious in the processing of meat as it determines the texture
of final product. So cross linking enzymes are exploited to tailor
these gelation properties. Enzymes like transglutaminase, laccase
and tyrosinase have recently been used to test for pork and chicken
proteins (Selinheimo, 2008).
Phenol decontamination using Tyrosinase
Various industries like paper, chemical, textile, mining, coal and
petroleum produce wastewaters that consist of the phenols and
its derivatives. Tyrosinase is capable of oxidizing the phenols
into insoluble substances that can be eliminated by precipitating
or filtering them (Fariaet al., 2007). Phenolic componds present
in aqueous solutions can be eradicated by adsorbing them onto
the granular activated carbon or cloth (Brasquet et al., 1999).
As tyrosine is detoxifying agent of xenobiotics having phenol
structure, so among them, chlorophenols are specific contaminants
present in wastewater (Marino et al., 2011). The industries such as
leather, textile, pharmaceutical and paper, generate different dyes
mostly azo dyes, which are a dangerous to environment. Under
certain conditions, they are decolorized by bacteria and then
degraded by the tyrosinase (Saratale et al., 2011). Mechanism as emulsifiers and to manufacture less fat and less calorie foods.
Natural polymers can be cross linked to produce new polymers
using mushroom tyrosinase (Faria et al., 2007). They form cross
links on the basis of accessibility and abundance of target protein.
Modifications in the properties are very important for use in
various fields like food processing (Heck et al., 2012). The enzyme
can be used for grafting of specific compounds to biopolymers and
yielding novel bioproducts. Tyrosinase provides an easy method in
the conversion of byproducts of food processing to environmentally
favorable items with valuable functional characteristics (Aberg et
of L –tyrosine conversion to L-DOPA and then to o-dopaquinone
involves the application of tyrosinase (Faria et al., 2007).
As there is a great demand for different enzymes in the industries,
tyrosinase is one ofsignificant commercial enzymes. Microbial
tyrosinases are highly promising enzymes for the pharmaceutical
and food bioprocessing technologies. However, to use these
microbial tyrosinases to fulfill their industrial potential, further
research is needed to be carried out.
Conflict of interest
No conflict of Interest
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