Laccase chem 124 Ax - ChemWiki

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Feb 20, 2013 (4 years and 5 months ago)

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1


Sahar Anjomshoaa

Chem 124 A

Dr.

Berben

Writing Assignment: Inorganic chemistry in Biology

Laccase

Laccase is a copper
-
containing enzyme, 1,4
-
benzenediol
oxidas
e

,

isolated from lacquer
tree,

Rhuse venifera and found in fungi and microorganisms

which are eukaryotes, but recently
they found the increase of laccase in prokaryotes of proteins with a specific feature of it in the
family enzyme. Laccase also found in gram positive and negative of bacteria like species living in
extreme habitats
.
1
, 2,

4

Lacc
ases are multicopper oxidas
es

of wide specificity that carry out one
-
electron oxidation of phenolic and related compounds, and

reduce O2 to water.
1
, 2

Laccases

are
polymeric and generally contain one each of type 1, type 2, type 3 copper centers per

subunit,
where the type 2 and type 3 are close together forming a trinuclear copper cluster and type 1 is
monocopper site.

The structure of the trinuclear copper site is s
imilar to the ascorbate
oxidase

and this is the place where the reduction of molecul
ar oxygen and re
lease of water happens.
T
here is a strong anti
-
ferro
magnetical coupling between these copper

which maintains a
hydroxyl bridge.
1
However, the

type 1 copper atom in laccase is 3
-
coordinate ,trigonal planar
and bound by one Cys and two His res
idues, but it lacks the axial ligand present in the Type 1
copper centre in ascorbate oxidase. The absence of the axial ligand is effecting the reduction
potential of the metalloenzyme.
1
, 4, 5

The easiest way to detect activity in Laccases is to use the spectrophotometer.
Sub
s
trates

that are commonly used with this method are ABTS, syringaldazine, 2,6
-
2


dimethoxyphenol, and dimethyl
-
p
-
phenylenediamine.

In type 1, there is
absorption of

611 nm

in U
V visible

and this is where the substrate oxidation takes place. In type 2 copper we can’t see
any absorption under the visible spectrum and in EPR studie
s reveals the paramagnetic. And, in

type 3 has
electron

absorption at 330 nm. This type is

one of the
other protein super families

which
have

the Tyrs and haemocyanine.
3

Laccases can be polymeric, and the enzymatically active form can be a dimer or trimer.
Other laccases, such as ones produces by the fungus
Pleurotus ostreatus
,

play a role in the
degradation of lignin, and can therefore be included in the broad category of
ligninases
.

Laccases can
also be used as the cathode in an enzyme catalyzed fuel cell. They can be paired
with an electron mediator to facilitate electron transfer to a solid electrode wire. Laccase is one
of the few oxidoreductases commercialized as industrial catalysts. The enzy
me can be used for
textile dyeing, wine cork making

and many other environmental and industrial
appliances.
6

By looking at the structure of Laccase, we can find the point group of each copper and
the symmetry of the whole structure.

The
re is not

a symmetry

in this structure

and we call it
C1. And, t
he point group is the collection of symmetry elements that satisfy the axioms of a
mathematical group. Th
e point
groups of these three types of Coppers that I came up with it
are

as follow;

type I Cop
per is C2h
,
type II

& III copper is C3v.

These three coppers are linked
together as a pyramidal shape. We also can find the IR and Raman spectroscopy of the enzyme
by finding the reducible representation of each copper by the formula and looking at the
character table
. In IR spectroscopy we see the changes of dipole moment. For finding the IR
from character table, we look at the product function of the first column and see if

each of the
3


Mulliken symbols have X,Y,Z in front of it or not. In Raman spectroscopy we see t
he
polarizability affects of electronic nature of chemical bonds in all direction. For finding the
Raman spectroscopy, we look at the product of the symbols in the second column. For

Copper
type I which has the point group of C2h, I found A1+E for IR and
Raman. And for Copper II and
III which have the point group of C3v, I found Au+Bu for IR and Ag+Bg for Raman.



Figure 1: Laccase structure
4

In this paper,
we talk about Laccase a multicopper enzyme, the catalyzing of it with all
the
activities originate

it from, and, the IR and Raman symmetry of it by the character table.

4


T
hese laccases

are everywhere, being spread in domains of life; more researches are needed to
better understand the physiological importance and also the effect of it in biotechnology f
ield.
4
They still need to do more research in order to see the presence of it in prokaryotic as well.





Figure 2: Laccase crystal structure
7











5


Reference

1.

Bertrand, T, C Jolivalt, P Briozzo, E Caminade, and N Joly. "Crystal Structure of a Four
-
Copper

Laccase

Complexed with an Arylamine: Insights into Substrate R
ecognition and
Correlation with
Kinetics."
Biochemistry including biophysical chemistry & molecul
ar
biology

41.23 (2002): 7325
-
7333. Web. 23 May 2010.
<https://vpn.lib.ucdavis.edu:11006/doi/full/10.1021/bi0201318>.

2.

"Definition of Laccase."
Chemi Cool

n. pag. Web. 23 May 2010.

<http://www.chemicool.com/definition/laccase.html>.

3.

Dedeyan, B, A Klonowska,

S Tagger, T Tron, and G Iacazio. "Biochemical and Molecular

Characterization of a Laccase from Marasmius quercophilus."
Applied and

Environmental Microbiology

66.3 (2000): 925
-
929. Web. 24 May 2010.

<http://aem.asm.org/cgi/content/full/66/3/925>.

4.

Harald,
C. "Laccase: structure, reactions, distribution."
Micron

(2004): 93
-
96. Web. 24 May 2010.

<http://www.elsevier.com/locate/micron>.

5.

Housecraft, C, and A Sharpe.
Inorganic Chemistry
. 3rd. Italy: Pearson
Educational Limited, 2008.

978
-

980. Print.

6.

"Laccase."
Biotechnology

1. (2005): 38
-
50. Web. 23 May 2010.

<http://www.bioportfolio.com/indepth/Laccase.html>.

7.

"T.versicolor laccase." Web. 23 May 2010.

<http://www.haraldkellner.com/assets/images/autogen/a_laccase3D.jpg>.