Student Studies CATALASE
http://aris.gusc.lv/BioThermodynamics/CATALASE.doc
Enzyme CATALASE radical reaction prevent non-enzymatic H2O2 chain reaction provocation
Āris Kaksis Riga Stradin’s University 2015
Human Physiology & Biochemistry
CAT increase velocity constant toxic radical 2H:-••:O-:-O:••-:H conversion to O2aqua +2H2O +Q
Three H2O2 hydrogen peroxide sources from nature at presence of oxygen in water medium O2aqua+H2O,
since 500 M-year’s atmospheric oxygen concentration is 20.95% volume per cents.
1. Heavy metal compounds having high oxidation number iron(III) Fe3+, cooper(II) Cu2+ ,
manganesium(IV) Mn4+, as well pollutant lead(IV) Pb4+ .
2. Ionization radiation: ultraviolet UV, x-ray, gamma  radiation, beta particles ( 01   un 01   ),
alpha particles 42   .
Human body 70 kg mass each second chemical elements carbon-14 146 C and potasium-40 40
19 K isotopes
irradiate 7000 beta particles 01   un 01   and high radiation energy absorbed forming in O2aqua+H2O medium of
tissues 1013 peroxide H2O2 molecules per second.
3. Enzymes aldehyde oxidoreductases in water medium at presence of oxygen O2aqua + H2O gives products
hydrogen peroxide H2O2.
Hydrogen peroxide decomposition reaction is spontaneous as
is exothermic enthalpy decreases Hr<0 evolving the heat Q in surrounding and entropy growth Sr>0 as from
two H2O2 + H2O2 molecules form tree molecules O2aqua + H2O + H2O free energy decreases and its change is
negative Hr-TSr= Gr<0 in thermodynamically favorable reaction.
High activation energy Ea=79 kJ/mol due to absence of catalyst and low geometric factor A=0.01 M-1s-1 make
the Arrhenius velocity constant expression negligible small:

k =A e

79000
Ea

RT =0.01 e 8 , 314 298 =0.011.41910-14=1.41910-16 M-1s-1
Velocity of reaction makes very small



v = k [H2O2]2=1.41910-16[H2O2]2

Ms-1 ;if [H2O2]=1 M ; v = k [H2O2] =1.19110-8
one molar peroxide [H2O2]=1 M solution each second converts of 1.191108 molecules to products only one 1
peroxide molecule, that all would be converted we should wait 1.191108 seconds, 3.78 years. One mol H2O2
contains Avogadro number of molecules NA = 6.0211023 particles/mol and expected time complete converting is
larger as 3.78 years 6.0211023/1.191108 = 51015 times and are 3.7851015 =1.91016 years. Universe age is
13.7 billion years, which is million times shorter period.
Catalyst CATALASE (CAT) is 1. involved into reaction 2. decreasing activation energy Ea and
3. improve geometrical factor A from worse value zero A => 0 to maximally optimized one A => 1 , that each
collision is geometrically active and effective 100% with geometric factor A = 1 favorable conversion to
products.
2H2O2 + CAT  H2O2CATH2O2  O2aqua+2H2O+Qexothermic+ CAT
toxic
transition state
biological goods
compound
active complex
oxygen+water+heat + CATALASE
Biocatalyst enzyme-CATALASE according Cambridge University professor Alana Fersht shows great catalytic

v enz =
activity:
k cat
KM
[E][H2O2]=3.6107[E][H2O2] ,

Usual catalase concentration is small
and v enz =0.36[H2O2] s-1 . Activation energy of catalase
Ea=29 J/mol and geometric factor A=0.1311 active collision fraction is 0.988 and velocity constant value is
0.1296 M-1s-1 , 98.8% of total collisions are active and converting to products O2aqua + 2H2O + Q:
[E]=10-8M

k

v
=
=A e
C AT 
k

29
Ea

 
RT = A e 8 , 314 298 = A0.988=0.1296 M-1s-1 ,
v = k [H2O2]2 =A0.988[H2O2]2
C AT 
[H2O2] =0.36[H2O2] ;
k

k
=
0,36
1,19  10 8
4.) 3010 times greater velocity constant increase
=(
1
6
Student Studies CATALASE
http://aris.gusc.lv/BioThermodynamics/CATALASE.doc
Advanced Studies of Chromo Protein CATALASE Heme pocket active site
Experimental research: http://aris.gusc.lv/06Daugavpils/Research/CATALASE.doc
H
O
M= 616.51 g/mol
O H
H2C
Asn147
His74
CH3
O
O
H3C
H2C
:N
N
Fe
H3C
3+
CH3
O
Fe
CH3
:N
N
Fe
3+
CH3
O
O
:N
N
CH3
O
H2C
M= 616.51 g/mol
CH3
O
O
O
:N
O
H
O
H3C
O
H2C
C34H32N4O4
H2C
O
Asn147
+ His74
CH3
O
M= 616.51 g/mol
3+
N
H2C
H
O
:N
N
O
O
:N
N
Asn147
His74
CH3
+
O H
O
H
CH3
C34H32N4O4
C34H32N4O4
Tyr357
Tyr357
Tyr357
CH2
CH2
CH2
Singlet •::O-:-O::• iron(III) Fe3+ on Heme center in to water medium conversed to triplet oxygen •:O≡:::≡O:•
Heme pocket with 28 hydrophobic amino acids – in waterless medium oxidation-reduction reaction absent:
Val72,Val73,Ala75,Val115,Ala116,Pro128,Gly130,Val145,Gly146,Phe153,Ile154,Ala157,Leu159,Phe160,
Pro161,Phe163,Ile164,Leu198,Leu298,Ala332,Phe333,Pro335,Met349,Leu350,Gly352,Ala356,Pro358,Ala434
Singlet •::O-:-O::• ————→ triplet •:O≡:::≡O:
Asn147
His74
CH3
O
H
O H
O
M= 616.51 g/mol
H2C
O
H3C
N
H2C
H3C
3+
H O
H
:N
N
O
O H
Asn147
His74
+ CH
3
N
O
O
CH3
H O
H
:N
O
H2C
CH3
O
CH3
O
O
HEM_.tgf
O
N
O
O
:N
Fe
3+
H2C
H O
H
:N
O
O
O
CH3
CH3
M= 616.51 g/mol
C34H32N4O4
C34H32N4O4
Tyr357
CH2
H
N
CH3
C34H32N4O4
H2C
H3C
4+
Asn147
His74
CH3
H O
HEMO2.tgf
:N
Fe
O
O
N
O
H2C
O
H O
HEM-O2.tgf
:N
Fe
M= 616.51 g/mol
Tyr357
CH2
Tyr357
CH2
H2O2 + H2O2 + CAT  H2O2CATH2O2  O2aqua + H2O + H2O + Q + CAT
toxic
transition state
biological goods
compound
active complex
oxygen + water + heat + CATALASE
Conclusions CATALASE
1. Catalyst CATALASE is involved.......... ..........
2. Catalyst decrease ..........
3. Catalyst improve ..........

4. Catalyst increase
k ....................
2